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<div class="chlinkprevnexttop"> <a href="chap0_mj.html">[Top of Book]</a>   <a href="chap0_mj.html#contents">[Contents]</a>    <a href="chap40_mj.html">[Previous Chapter]</a>    <a href="chap42_mj.html">[Next Chapter]</a>   </div>

<p id="mathjaxlink" class="pcenter"><a href="chap41.html">[MathJax off]</a></p>
<p><a id="X87115591851FB7F4" name="X87115591851FB7F4"></a></p>
<div class="ChapSects"><a href="chap41_mj.html#X87115591851FB7F4">41 <span class="Heading">Group Actions</span></a>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X83661AFD7B7BD1D9">41.1 <span class="Heading">About Group Actions</span></a>
</span>
</div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X81B8F9CD868CD953">41.2 <span class="Heading">Basic Actions</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7FE417DD837987B4">41.2-1 OnPoints</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7960924D84B5B18F">41.2-2 OnRight</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X832DF5327ECA0E44">41.2-3 OnLeftInverse</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X85AA04347CD117F9">41.2-4 OnSets</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X832CC5F87EEA4A7E">41.2-5 OnTuples</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X80DAA1D2855B1456">41.2-6 OnPairs</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7C10492081D72376">41.2-7 OnSetsSets</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7E23686E7A9D3A20">41.2-8 OnSetsDisjointSets</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7ADE244E819035FF">41.2-9 OnSetsTuples</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7FF556CD7E6739A9">41.2-10 OnTuplesSets</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X844E902382EB4151">41.2-11 OnTuplesTuples</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X86DC2DD5829CAD9A">41.2-12 OnLines</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7FA394D27E721E2B">41.2-13 OnIndeterminates</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7BA8D76586F1F06E">41.2-14 Permuted</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X85124D197F0F9C4D">41.2-15 OnSubspacesByCanonicalBasis</a></span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X82181CA07A5B2056">41.3 <span class="Heading">Action on canonical representatives</span></a>
</span>
</div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X81E0FF0587C54543">41.4 <span class="Heading">Orbits</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X80E0234E7BD79409">41.4-1 Orbit</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X86BCAE17869BBEAA">41.4-2 Orbits</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X86BC8B958123F953">41.4-3 <span class="Heading">OrbitsDomain</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X799910CF832EDC45">41.4-4 OrbitLength</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8032F73078DF2DDB">41.4-5 <span class="Heading">OrbitLengths</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8520E2487F7E98AF">41.4-6 <span class="Heading">OrbitLengthsDomain</span></a>
</span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X797BD60E7ACEF1B1">41.5 <span class="Heading">Stabilizers</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7C34EC437EF598BF">41.5-1 OrbitStabilizer</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X86FB962786397E02">41.5-2 Stabilizer</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X78C3A8568414BC44">41.5-3 OrbitStabilizerAlgorithm</a></span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X7A9389097BAF670D">41.6 <span class="Heading">Elements with Prescribed Images</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X857DC7B085EB0539">41.6-1 RepresentativeAction</a></span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X87F73CCA7921DE65">41.7 <span class="Heading">The Permutation Image of an Action</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X78E6A002835288A4">41.7-1 <span class="Heading">ActionHomomorphism</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X85A8E93D786C3C9C">41.7-2 Action</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X86FF54A383B73967">41.7-3 SparseActionHomomorphism</a></span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X7FED50ED7ACA5FB2">41.8 <span class="Heading">Action of a group on itself</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X784D417D87F4E58D">41.8-1 FactorCosetAction</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8561DEBA79E01ABD">41.8-2 RegularActionHomomorphism</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X835317A7847477D4">41.8-3 AbelianSubfactorAction</a></span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X807AA91E841D132B">41.9 <span class="Heading">Permutations Induced by Elements and Cycles</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7807A33381DCAB26">41.9-1 <span class="Heading">Permutation</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X81D4EA42810974A0">41.9-2 PermutationCycle</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X80AF6E0683CA7F14">41.9-3 Cycle</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7F559E897B333758">41.9-4 CycleLength</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7F3B387A7FD8AE5E">41.9-5 Cycles</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X83040A6080C2C6C6">41.9-6 CycleLengths</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X87FDA6838065CDCB">41.9-7 <span class="Heading">CycleIndex</span></a>
</span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X850A84618421392A">41.10 <span class="Heading">Tests for Actions</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X79B15750851828CB">41.10-1 <span class="Heading">IsTransitive</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8295D733796B7A37">41.10-2 <span class="Heading">Transitivity</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8166A6A17C8D6E73">41.10-3 <span class="Heading">RankAction</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7B77040F8543CD6E">41.10-4 <span class="Heading">IsSemiRegular</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7CF02C4785F0EAB5">41.10-5 <span class="Heading">IsRegular</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7CB1D74280F92AFC">41.10-6 <span class="Heading">Earns</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X84C19AD68247B760">41.10-7 <span class="Heading">IsPrimitive</span></a>
</span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X7E9D3D0B7A9A8572">41.11 <span class="Heading">Block Systems</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X84FE699F85371643">41.11-1 <span class="Heading">Blocks</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X79936EB97AAD1144">41.11-2 <span class="Heading">MaximalBlocks</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7941DB6380B74510">41.11-3 <span class="Heading">RepresentativesMinimalBlocks</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X835658B07B28EF3B">41.11-4 AllBlocks</a></span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X7FD3D2D2788709B7">41.12 <span class="Heading">External Sets</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8264C3C479FF0A8B">41.12-1 IsExternalSet</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7C90F648793E47DD">41.12-2 ExternalSet</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7B9DB15D80CE28B4">41.12-3 ActingDomain</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X86153CB087394DC1">41.12-4 FunctionAction</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X86A0CC1479A5932A">41.12-5 HomeEnumerator</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X879DE63C7858453C">41.12-6 IsExternalSubset</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X87D1EA1486D86233">41.12-7 ExternalSubset</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7E081F568407317F">41.12-8 IsExternalOrbit</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7FB656AE7A066C35">41.12-9 ExternalOrbit</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7BAFF02B7D6DF9F2">41.12-10 StabilizerOfExternalSet</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X867262FA82FDD592">41.12-11 <span class="Heading">ExternalOrbits</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X7A64EF807CE8893E">41.12-12 <span class="Heading">ExternalOrbitsStabilizers</span></a>
</span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8048AE727A7F1A2F">41.12-13 CanonicalRepresentativeOfExternalSet</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X8071A8D784DC8325">41.12-14 CanonicalRepresentativeDeterminatorOfExternalSet</a></span>
<span class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X85E9A6A77B8D00B8">41.12-15 ActorOfExternalSet</a></span>
<span class="ContSS"><br /><div="chlinkprevnexttop"> <a href="chap0_mj.html">[Top of Book]</a>   <a href="chap0_mj.html#contents">[Contents]</a>    <a href="chap40_mj.html">[Previous Chapter]</a>    <a href="chap42_mj.html">[Next Chapter]</a>   </div>
< class>brspan " nbsp</java.lang.StringIndexOutOfBoundsException: Range [69, 65) out of bounds for length 161
</div></div>
</div>

<h3>41 <span class=/pan

<p>A<>

<p>In <strong class="pkg">GAP</strong>, <span class="SimpleMath">\(\Omega\)</span> can be a duplicate-free collection (an object that permits access to its elements via the <span class="SimpleMath">\(\Omega[n]\)</span> operation, for example a list), it does not need to be sorted (see <code class="func">IsSet</code> (<a href="chap21_mj.html#X80CDAF45782E8DCB"><span class="RefLink">21.17-4</span></a>)).</p>

<p>The acting function <span class="SimpleMath">\(\mu\)</span class="ContSS"><br /><span class="nocss">  #"412- java.lang.StringIndexOutOfBoundsException: Range [124, 122) out of bounds for length 133

<p>In <strong class="pkg">GAP</strong>, groups span"ontSS"< >span =n>nbsp;<span>a href"java.lang.StringIndexOutOfBoundsException: Range [85, 84) out of bounds for length 134

<p><strong class="pkg">GAP</strong> does not test whether the acting function <span class="SimpleMath">\(\mu\)</span> satisfies the conditions for aspanclass"ontSS" >java.lang.StringIndexOutOfBoundsException: Range [33, 32) out of bounds for length 145

<p>The first section of this chapter, <a href="chap41_mj.html#X83661AFD7B7BD1D9"><span class="class="ContSS"><br /><span class="nocss">  </span><a href="chap41_mj.html#X844E902382EB4151span

spanbr/spanclass"ocss>nbsp;</<a "htmlXB"41.14 <>

<p>The sections <a href="chap41_mj.html#X87F73CCA7921DE65"><span class="RefLink">41.7</span></a> and <a href="chap41_mj.html#X7FED50ED7ACA5FB2"><><div

<p>The other sections then describe operations to compute orbits, stabilizers, as well as properties of actions.</p>

<p>Finally section <a href="chap41_mj.html#X7FD3D2D2788709B7"><span class="RefLink">41.12</span></a> describes the concept of <q>external sets</q> which represent the concept of a <em><span class="SimpleMath">\(G\)</span>-set</em> and span

<p><a id="X83661AFD7B7BD1D9" name="X83661AFD7B7BD1D9"></a></p>

<></h4

< syntax  isjava.lang.StringIndexOutOfBoundsException: Range [49, 45) out of bounds for length 367


<dl>
<dt><strong class="Mark"><code class="code">OrbitsDomain</code><span class="SimpleMath">\(( G, \Omega[, \mu] )\)</span></strong></dt>
<dd><p>The acting function <span class="SimpleMath">\(\mu\)</span> is optional. If it is not given, the built-in action <code div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap41_mj.html#X797BD60E7ACEF1B1">41.5 <span

<ddjava.lang.StringIndexOutOfBoundsException: Index 5 out of bounds for length 5
<dt><strong class="Mark"><code class="code">OrbitsDomain</code><span class="SimpleMath">\(( G, \Omega, gens, acts[, \mu] )\)</span><<>/>
<dd><p>This second version of <code class="func">OrbitsDomain</code> (<a href="chap41_mj.html#X86BC8B958123F953"><span class="RefLink">41.4-3</span></a>) permits one to implement an action induced by a homomorphism: If the</span>

<p>Here <span class="SimpleMath">\(gens\)</span> must be a set of generators of <span class="SimpleMath">\(G\)</span> and <span class="SimpleMath">/

<p>The advantage of this notation is that <strong java.lang.StringIndexOutOfBoundsException: Index 52 out of bounds for length 7

<p><strong class="pkg">GAP</strong> does not test whether the mapping=java.lang.StringIndexOutOfBoundsException: Range [21, 19) out of bounds for length 151

</dd>
<dt><strong classclass=>="<java.lang.StringIndexOutOfBoundsException: Range [50, 49) out of bounds for length 185
<dd><p>A third variant is to call the operation with an external set, which then provides <span class="SimpleMath">\(G\)</span>, <span class="SimpleMath">\(\Omega\)</span> and <span java.lang.StringIndexOutOfBoundsException: Index 186 out of bounds for length 7

<dd>
</dl>
<p>For operations like <code class="func">< "> ><java.lang.StringIndexOutOfBoundsException: Range [39, 38) out of bounds for length 149

<aidjava.lang.StringIndexOutOfBoundsException: Range [33, 27) out of bounds for length 62

<h4>41.2 <span class="Heading"/

<p><strong class="pkg">GAP</strong> already provides />

<p>If one needs an action for which no acting function is provided by the library it can be implemented via a <strong class="pkg">GAP</strong> function that conforms to the syntax</p>

<p><code class="code">actfun( omega, g )</code></p>

<p>where <code class="code">omega</code> is an element of the action domain, <code class="code">g</code> is an element of the acting group, and the return span class"ontSS"/=nocss>nbsp;nbsp<> =.#FB387"41.-</<span>

<p>For example one could define the following function that acts on pairs of polynomials via <code class="func">OnIndeterminates</code> (<a href="chap41_mj.html#X7FA394D27E721E2B"><span class="RefLink">41.2-13</span></a>):</p>


<div class="example"><pre>
OnIndeterminatesPairs:= function( polypair, g )
  return [ OnIndeterminates( polypair[1], g ),
           2], g)]java.lang.StringIndexOutOfBoundsException: Index 48 out of bounds for length 48
;
</pre></div>

<p>Note that this function <em>must</em> implement a group action </pan>

<p><a id="java.lang.StringIndexOutOfBoundsException: Index 12 out of bounds for length 7

<h5>41.2-1 OnPoints</h5>

tdleftjava.lang.StringIndexOutOfBoundsException: Range [80, 79) out of bounds for length 243
<p>returns <code class="code"><var class="Arg">pnt</var> ^ <var class="Arg"</span>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">OnPoints( 1, (1,2,3) );</span>
2
<span class="GAPprompt">gap></span> <span class="GAPinput">OnPoints( (1,2), (1,2,3) );</span>
(2,3)
<span class="GAPprompt">gap></span> <span class="GAPinput">g:= Group( (1,2,3), (2,3,4) );;</span>
<span class">&;/span><span class=""Orbit g,1 OnPoints )<span>
[ 1, 2, 3, 4 ]
</pre></div>

<p><a id="X7960924D84B5B18F" name="X7960924D84B5B18F"></a></p>

<h5>41.2-2 OnRight</h5>

< class""><table ""width"%">trtdclass"dleft">code ">#8227 OnRightcode>( <var class="Arg">pnt</var>, <var class="Arg">g</var> )</td><td class="tdright">( function )</td></tr></table></div>
<pclass="ContSS><r />span class="nocssnbsp&;/>a=chap41_mj.#X7C90F648793E47DD41.- />/span>


<div class="example"><pre class=""> />spanjava.lang.StringIndexOutOfBoundsException: Range [39, 38) out of bounds for length 142
<span class="GAPprompt">gap></span> <span class="GAPinput">OnRight( [ 1, 2 ], [ [ 1, 2 ], [ 3, 4 ] ] );</span>
[ 7, 10 ]
<span class="GAPprompt">gap></span> <span class="GAPinput">OnRight( (1,2,3), (2,3,4) );</span>
(1,3)(2,4)
java.lang.StringIndexOutOfBoundsException: Index 107 out of bounds for length 100
< class=">gapgt<span java.lang.StringIndexOutOfBoundsException: Range [45, 44) out of bounds for length 93
[ (), (1,2,3), (2,3,4), (1,3,2), (1,3)(2,4), (1,2)(3,4), (2,4,3),
  ,) java.lang.StringIndexOutOfBoundsException: Index 50 out of bounds for length 50
</pre></div>

<p><a id="X832DF5327ECA0E44" name="java.lang.StringIndexOutOfBoundsException: Index 51 out of bounds for length 7

<h5>41.-3 OnLeftInverse</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OnLeftInverse</code>( <var class="Arg">pnt</var>, <var class="Arg">g</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>returns <span class="SimpleMath">\(\textit{g}^{{-1}}\)</span> <code class="code">* <var class="Arg">pnt</var></code>. Forming the inverse is necessary to make this a java.lang.StringIndexOutOfBoundsException: Index 175 out of bounds for length 161

<


<div class="example"><pre>
<">OnLeftInverse( [ 1, 2 ], [ [ 1, 2 ],  3,4]]java.lang.StringIndexOutOfBoundsException: Index 119 out of bounds for length 119

<span class="GAPprompt">gap></span> <span class="GAPinput">OnLeftInverse( (1,2,3), (2,3,4) );</span>
(,,4)
<span class="GAPprompt">gap></span> <span class="GAPinput">g:= Group( (1,2,3), (2,3,4) );;</span>
<span class="GAPprompt">gap></span> <span java.lang.StringIndexOutOfBoundsException: Range [0, 50) out of bounds for length 0
[ (), (1,3,2), (2,4,3), (1,2,3), (1,3)(2,4), (1,2)(3,4), (2,3,4),
  (1,2,4), (1,3,4), (1,4,3), (1,4,2), (1,4)(2,3) ]
</pre></div>

<p><a id="X85AA04347CD117F9" name="X85AA04347CD117F9"></a></p>

<java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OnSets</code>( <var class="Arg">set</var>, <var class="Arg">g</var> )</td><td class="tdright">( function )</td></tr></table></div>
><java.lang.StringIndexOutOfBoundsException: Range [18, 17) out of bounds for length 525

<p><code class="func">OnSets</code> is for example used to compute the action of a permutation group on blocks.</p>

<p>(<code class


<=">java.lang.StringIndexOutOfBoundsException: Range [26, 25) out of bounds for length 26
<span class
[1  java.lang.StringIndexOutOfBoundsException: Index 8 out of bounds for length 8
<span class="GAPprompt">gap></java.lang.StringIndexOutOfBoundsException: Index 36 out of bounds for length 4
[ 23)(1,)]
<span class="GAPprompt">gap></span> <span class="GAPinput">g:= Group( (1,2,3), (2,3,4) );;</span>
<="GAPprompt">></pan span"" g [, ,;/span
[ [ 1, 2 ], [ 2, 3 ], [ 1, 3 ], [ 3, 4 ], [ 1, 4 ], [ 2, 4 ] ]
</pre></div>

<p</dd>

<h55 OnTuples<h5

<div class="func"><table class="func" width="100%"><tr><td class="tdleft">
<>Let<="rg"tup</ar alist code =""OnTuples<codereturnsthelistformed the imagesofall  span class="SimpleMath">\(x\)</span> of <var class="Arg">tup</var> via the action function <code class="func">OnPoints</code> (<a href="chap41_mj.html#X7FE417DD837987B4"><span class="RefLink">41.2-1</span></a>), applied to <span class="SimpleMath">\(x\)</span> and <var class="Arg">g</var>.</p>

<p classpkg></does  testwhether   < =SimpleMath mapsto\/>actually ahomomorphismthe java.lang.StringIndexOutOfBoundsException: Range [176, 175) out of bounds for length 218


<div class="example"><pre>
<span">OnTuples( [ 1, 3 ], (1,,3) );/span>
[ 2, 1 ]
<span class="java.lang.StringIndexOutOfBoundsException: Index 21 out of bounds for length 5
[(,),  (,3 ]
<span class="GAPprompt">gap></span> <span class="GAPinput">g:= Group( (1,2,3), (2,3,4) );;</span>
<span class="GAPprompt">gap></span> <span class="java.lang.StringIndexOutOfBoundsException: Index 58 out of bounds for length 0
[ [ 1, 2 ], [ 2, 3 ], [ 1, 3 ], [ 3, 1 ], [ 3, 4 ], [ 2, 1 ],
  [ 1, 4 ], [ 4, 1 ], [ 4, 2 ], [ 3, 2 ], [ 2, 4 ], [ 4, 3 ] ]
>

<p>return (polypair]  )java.lang.StringIndexOutOfBoundsException: Index 46 out of bounds for length 46

<h5>41.2-6 OnPairs</h5>

<div class="func"><table class=
<p>is a special case of <code class="func">OnTuples</code> (<a href="chap41_mj.html#X832CC5F87EEA4A7E"><span class="RefLink">41.2-5</span></a>) for lists <var class="java.lang.StringIndexOutOfBoundsException: Range [0, 169) out of bounds for length 0

<p><a id="X7C10492081D72376" name="X7C10492081D72376"></a></p>

<h5>41.2-7 OnSetsSets<java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<div class="func"><table span"GAPprompt"gap&t;/>span class"APinput">OnPoints( (1,2), (1,2,3) );</span>
<p>implements the action on sets of    special case   arepairwise disjoint it is possible use < class=func>OnSetsDisjointSets</code(<"chap41_mjhtml>span class">.-<java.lang.StringIndexOutOfBoundsException: Range [246, 245) out of bounds for length 463


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">OnSetsSets( [ [ 1, 2 ], [ 3, 4 ] ], (1,2,3) );</span>
[ [ 1, 4 ], [ 2, 3 ] ]
<span class="GAPprompt">gap></span> <span<span class=GAPpromptgap&t<span<java.lang.StringIndexOutOfBoundsException: Range [45, 44) out of bounds for length 93
< class"GAPprompt">&t</span><spanclass="GAPinput"Orbit(g,[[,2 ] [ , 4]] OnSetsSets <span
 [[,2],[ ,4  ,  , 4 , [,3] ,
  [ [ 1, 3 ], [ 2, 4 ] ] ]
</pre></div>

<p><a id="X7E23686E7A9D3A20" name="X7E23686E7A9D3A20 code class="code>class""><var>*var "g/</java.lang.StringIndexOutOfBoundsException: Range [91, 89) out of bounds for length 468

<h5>41.2-8 OnSetsDisjointSets</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; java.lang.StringIndexOutOfBoundsException: Index 113 out of bounds for length 0
<p>implements the action on sets of pairwise disjoint sets (see also <code class="func">OnSetsSets</code> (<a href="chap41_mj.html#X7C10492081D72376"><span class="RefLink">41.2-7</span></a>)). <var class="Arg">

<<s "APprompt">><span> <pan class="APinput>: Group( (12,3),), (2,34 );</span>

<h5>41.2-9 <panclass=GAPprompt">gap></span> <span class="GAPinput">Orbit( g, (), OnRight );</span>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OnSetsTuples</code>( <var class="Arg">set</var>, <var class="Arg">g</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>implements the action class">tableclass=""java.lang.StringIndexOutOfBoundsException: Range [44, 43) out of bounds for length 248


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">OnSetsTuples( [ [ 1, 2 ], [ 3, 4 ] ], (1,2,3) );</span>
[[1  ], [23  ]
<span class="GAPprompt">gap></span> <span class="GAPinput">g:= Group( (1,2,3), (2,3,4) );;</span>
span=GAPprompt"gap&;<//pan span class="GAPinput">Orbit( g, [ [ 1, 2 ], [ 3, 4 ] ], OnSetsTuples );</span>
[ [ [ 1, 2 ], [ 3, 4 ] ], [ [ 1, 4 ], [ 2, 3 ] ],
  [ [ 1, 3 ], [ 4, 2 ] ], [ [ 2, 4 ], [ 3, 1 ] ],
  [ [ 2, 1 ], [ 4, 3 ] ], [ [ 3
</pre></div>

<p><a id="X7FF556CD7E6739A9" name="X7FF556CD7E6739A9"></a></java.lang.StringIndexOutOfBoundsException: Range [0, 61) out of bounds for length 7

<h5>41.2-10 OnTuplesSets</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OnTuplesSets<pan class="GAPprompt">gap></span> <span class="GAPinput">Orbit( g, (), OnLeftInverse );</span>
<p>implements the action on tuples of sets. <var class="Arg">set</var> must be a list whose entries are again sorted lists, otherwise an error is triggered (see <a(1,2)(,,4, (43 (1,,2, (,),)java.lang.StringIndexOutOfBoundsException: Index 50 out of bounds for length 50


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">OnTuplesSets( [ [ 2, 3 ], [ 3<Letclass="Arg"set</var> be a proper set (see <a href="chap21_mj.html#X80ABC25582343910"><span class="RefLink">21.19</span></a>). <code class="func">OnSets</code> returns the proper set formed by the java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
[ [ 1, 3 ], [ 1, 4 ] ]
<span,2]
<">Orbit   [ 1 2,[3, 4] ,  ;</span>
[ [ [ 1, 2 ], [ 3, 4 ] ], [ [ 2, 3 ], [ 1, 4 ] ],
  [ [ 1, 3 ], [ 2, 4 ] ], [ [ 3, 4 ], [ 1, 2 ] ],
  [ [ 1, 4 ], [ 2, 3 ] ], [ [ 2, 4 ], [ 1, 3 ]   ,2, [, ]  1,3][, 4,[,4]  2,]]
</pre></div>

<p><a id="X844E902382EB4151" name="X844E902382EB4151"></<div class="func"><table class="func" width="100%"><tr><tclass="tdleft"><code class="func">&#8227; OnTuples</code>( <var class="Arg">tup</var>, <var class="Arg">g</var> )</td><td class="tdright">( function&&gt;< "rg>java.lang.StringIndexOutOfBoundsException: Range [29, 27) out of bounds for length 427

<h5>41.2-11 OnTuplesTuples</h5>

<div class="func"><table class="func" width="100%"><tr><java.lang.StringIndexOutOfBoundsException: Index 58 out of bounds for length 0
<p>implements the action on tuples of tuples.</p>


< java.lang.StringIndexOutOfBoundsException: Range [11, 10) out of bounds for length 26
<span class="GAPprompt">gap></span> <span class="GAPinput">OnTuplesTuples( [ [ 2, 3 ], [ 3, 4 ] ], (1,2,3) );</span>
[ [ 3, 1 ], [ 1, 4 ] ]
<span class="GAPprompt">gap><< java.lang.StringIndexOutOfBoundsException: Range [12, 11) out of bounds for length 100
<span class="GAPprompt">gap></span> <[ [ 1, 2 ], [ 2, 3 ], [ 1, 3 ], [ 3, 1 ], [ ,
[ [ [ 1, 2 ], [ 3, 4 ] ], [ [ 2, 3 ], [ 1, 4 ] ],
  [ [ 1, 3 ], [ 4, 2 ] ], [ [ 3, 1 ], [ 2, 4 
  <4126java.lang.StringIndexOutOfBoundsException: Range [19, 18) out of bounds for length 23
 [ , , ,3 ]] [ 4, , ,2  ,
  [ [ 4, 2 ], [ 1, 3 ] ], [ [ 3, 2 ], [ 4, 1 ] ],
  [ [ 2, 4 ], [ 3, 1 ] ], [ [ 4, 3 ], [ 2, 1 ] ] ]
</pre></div>

<p><a id="X86DC2DD5829CAD9A" name="java.lang.StringIndexOutOfBoundsException: Index 39 out of bounds for length 0

<h5>41.2-12 OnLines</h5>

<div class="func"><table class=p>implements  onof . Forjava.lang.StringIndexOutOfBoundsException: Range [50, 49) out of bounds for length 463
p< =Arg></  aem><emrowvector that is  firstentry isnormedto java.lang.StringIndexOutOfBoundsException: Range [128, 125) out of bounds for length 669

<p>This action corresponds to the projective action of a matrix group on one-dimensional subspaces.</p>

<p>If <var class="Arg">vec</var> is a zero vector or is not normed then an error is triggered (see <a href="chap41_mj.html#X82181CA07A5B2056"><span class="RefLink">41.3</span></a>).</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">OnLines( [ 1, 2 ], [ [ 1, 2 ], [ 3, 4 ] ] );</span>
[ 1, 10/7 ]
<span class="GAPprompt">gap></span> <span class
[ Z(5)^0, 0<iv "><>
< class="APprompt"gapgt;><spanclass="GAPinput">:=Action(,OrbitglvOnLines)O)</span>
Group([ (2,3,5,6), (1,2,4)  1 4 ,[2   java.lang.StringIndexOutOfBoundsException: Index 22 out of bounds for length 22
</pre></div>

<p><a id="X7FA394D27E721E2B" name="X7FA394D27E721E2B"></spanclass="GAPprompt"gap&;/><java.lang.StringIndexOutOfBoundsException: Range [45, 44) out of bounds for length 116

<41.13 <java.lang.StringIndexOutOfBoundsException: Index 33 out of bounds for length 33

<div class="func"><table class="func" width="100%"><tr></<div
<p> permutationvar java.lang.StringIndexOutOfBoundsException: Range [28, 27) out of bounds for length 167


<<p>i theaction  setssee codejava.lang.StringIndexOutOfBoundsException: Range [81, 80) out of bounds for length 403
<classG"gap&</java.lang.StringIndexOutOfBoundsException: Range [38, 37) out of bounds for length 132
<span class="GAPprompt">gap></span> <span class="GAPinput">OnIndeterminates(x^7*y+x*y^4,(1,17)(2,28));</span>
x_17^7*x_28+x_17*x_28^4
<span class="GAPprompt">gap></<>a="" java.lang.StringIndexOutOfBoundsException: Range [34, 33) out of bounds for length 62
Group([ (1,2), (3,4) ])
</pre></div>

<p><a id="X7BA8D76586F1F06E" name="X7BA8D76586F1F06E"></a></p>

<h5>41.2-14 Permuted</h5>

<divclass=func>table class="unc"width"100%><r><td class="tdleft"><code class="func">‣ Permuted</code>( <var class="Arg">list</var>, <var class="Arg">perm</var> )</td><td class="tdright">( method )</td></tr></table></div>
pThe    < class""Permuted<code<ahrefchap21_mj.tml#X7B5A19098406347A"><span class="RefLink">21.20-17</span></a>) being used to implement a permutation action on a domain:</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=Group((1,2,3),(1,2));;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">dom:=[ "a", "b", "c" ];;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">Orbit(g,dom,Permuted);</span>
[ [ "a", "b", "c" ], [ "c", "a", "b" ], [ "b", "a", "c" ],
  [ "b", "c", "a" ], [ "a", "c", "b" ], [ "c", "b", "a" ] ]
</pre></div>

<p><a idh5>41210</>

<h5>41.2-15 div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="    ofjava.lang.StringIndexOutOfBoundsException: Range [43, 42) out of bounds for length 247

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OnSubspacesByCanonicalBasis<java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OnSubspacesByCanonicalBasisConcatenations</code>( <var class="Arg">basvec</var>, <var class="Arg">mat</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>implements the operation of a matrix group on subspaces of a vector space. <var class="Arg">bas  [  1, 3],[2,4 ], [3,4] [1,2],

<p><var class="Arg">bas</var> must be given in Hermite normal form, otherwise</pre>/iv>

<p<a id=X82181CA07A5B2056 ="82181CA07A5B2056"<a>/p

<h4>41.3 <span class="Heading">Action on canonical representatives</span></h4>

<p>A varietydiv=func">table class=f" =100">td class=>code class=f>#;</>(<var class""set<var>< class=""g/>)</d> class=tdright"&;nbsp</<tr<java.lang.StringIndexOutOfBoundsException: Range [243, 242) out of bounds for length 249

<p>If orbit seeds or domain elements are not given in the required form <strong class="pkg">GAP</strong> will


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">Orbit(SymmetricGroup(5),[[2,4],[1,3]],OnSetsSets);</span>
Error, Action not well-defined. See the manual section
`java.lang.StringIndexOutOfBoundsException: Range [9, 8) out of bounds for length 40
</pre></div>

<p>In this case the affected domain elements have to be   [, , ,       ,3 java.lang.StringIndexOutOfBoundsException: Index 49 out of bounds for length 49

<p>(A similar error could arise if a user-defined action />/iv>

<p><a id="X81E0FF0587C54543" name="X81E0FF0587C54543"></a></p>

<h4>41.4 <span class="Heading">Orbits</java.lang.StringIndexOutOfBoundsException: Index 43 out of bounds for length 0

<p>If a group <span class="SimpleMath">\(G\)</span> acts on a set <span class="SimpleMath">\(\Omega\)</span>, the set of all images of <span class="SimpleMath">\(x \in \Omega\)</span> under elements of <span class="SimpleMath">\(G\)</span> is called the <em>orbit</em> of <span class="SimpleMath">\(x\)</span>. The set of orbits of <span class="SimpleMath">\(G\)</span> is a partition of <span class="SimpleMath">\(\Let var =Arg><var bea<>normed>  that entryis  theidentity the , codeclassfunc></>a hrefchtml"< =RefLink>2/>/>)Thefunctioncode ="<>returns    from java.lang.StringIndexOutOfBoundsException: Range [383, 382) out of bounds for length 669

<p>classGAPprompt>;><java.lang.StringIndexOutOfBoundsException: Range [45, 44) out of bounds for length 98

<>.-/>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; Orbit</code>( <var/>/>
<p>The orbit of the point <var class="Arg">pnt</var> is the list of all java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0

<p>(Note that the arrangement of points in this list is not defined by the operation.)</p>

<p>The orbit of <var class="Arg">pnt</var> will always contain one element that is <em>equal</em> to <var class="Arg">pnt</var>, however for performance reasons this element is not necessarily <em>identical</em> to <var class="Arg">pnt</var>, in particular if <var class="Arg">pnt</var> is mutable.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=Group((1,3,2),(2,4,3));;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">Orbit(g,1);</span>
[1, 3,,4 java.lang.StringIndexOutOfBoundsException: Index 14 out of bounds for length 14
<span class="GAPprompt">gap
[ 
<pre>

<p>(See>41214 Permuted<h5>

<>a=" "X86BCAE17869BBEAA//>

<h5>41.4-2 Orbits</h5>

<div class="p>The following  <code class=>Permuted</> (ahref=chap21_mj.#"< class"">.20-7<span/  used   apermutationactionon :>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><span""gapgt<span < "">dom=","b,c];/java.lang.StringIndexOutOfBoundsException: Range [93, 92) out of bounds for length 93
<p>returnsjava.lang.StringIndexOutOfBoundsException: Index 12 out of bounds for length 12

<p>For a permutation

<p>(Note that the arrangement java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0

<p><a id="X86BC8B958123F953" name="X86BC8B958123F953"></a></p>

<h5>41.4-3 <span class="Heading">OrbitsDomain</span></h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OrbitsDomain</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>] )</td>
<div
<div class="func"><<h441.3<span class=Heading"Action on canonical representatives</span></h4>
<p>returns a list of thejava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p>This operation is often faster than <code class="func">Orbitsjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p>For a permutation group <var class="Arg">G</var>, one may also invoke this as <code class="code">OrbitsDomain(<var class="Arg">G</var>)</code

<>(ote that the arrangement oforbits or of points within one orbit is not defined by the operation.)</p>


">prejava.lang.StringIndexOutOfBoundsException: Index 26 out of bounds for length 26
<span
<class">
[ [ 1, 3, 2, 4 ], [ 5 ] ]
<span class="GAPprompt">gap></span> p> id"X81E0FF0587C54543" name=X81E0FF0587C54543"></a></p>
[ [ [ 1, 2, 3 ], [ 3, 1, 2 ], [ 1, 4, 2 ], [ 2, 3, 1 ], [ 2, 1, 4 ],
      [ 3, 4, 1 ], [ 1, 3, 4 ], [ 4">()/pan> acts on a set <span class="SimpleMath">\(\Omega\)</span>, the set of all images of <span class="SimpleMath">\(x \in \Omega\)</span> under elements of <span class="SimpleMath">\(G\)</span> is called the <em>orbit</em> of <span class="java.lang.StringIndexOutOfBoundsException: Index 293 out of bounds for length 0
      ,,3 ] 3, 2,4 ], [, 3 2]]java.lang.StringIndexOutOfBoundsException: Index 46 out of bounds for length 46
  [ [ 1, 2, 4 ], [ 3, 1, 4 ], [ 1, 4, 3 ], [ 2, 3, 4 ], [ 2, 1, 3 ],
      [ 3, 4, 2 ], [ 1, 3, 2 ], [ 4, 2, 3 ], [ 4, 1, 2 ],
      [ 2, 4, 1 ], [ 3, 2, 1 ], [ 4, 3, 1 ] ] ]
<span class="GAPprompt">gap></span> <span class="GAPinput">OrbitsDomain(g,GF(2)^2,[(1,2,3),(1,4)(2,3)],</span>
<span class="GAPprompt">></span> <span class="GAPinput">[[[Z(2)^0,Z(2)^0],[Z(2)^0,0*Z(2)]],[[Z(2)^0,0*Z(2)],[0*Z(2),Z(2)^0]]]);</span>
[ [ <an immutable GF2 vector of length 2> ],
  [ <an immutable GF2 vector of length 2>,
      <an immutable GF2 vector of length 2>,
      <an immutable GF2 vector of length 2> ] ]
</pre></div>

<p>(See Section <a href="chap41_mj.html#X81B8F9CD868CD953"><span class="RefLink">41.2</span></a> for information about specific actions.)</p>

<p><a id="X799910CF832EDC45" name="X799910CF832EDC45"></a></p>

<h5>41.4-4 OrbitLength</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OrbitLength</code>( <var class="Arg">G</var>[, <var class="Arg">Omega</var>], <var class="Arg">pnt</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>] )</td><td class="tdright">( operation )</td></tr></p>The orbit of the point <var class="Arg">pnt</var> is the list of all images of <var class="Arg">pnt</var> under the action of the group <var class="Arg">G</var> w.r.t. the action function <var class="Arg">act</var> or <code class="func">OnPoints</code> (<a href="chap41_mj.html#X7FE417DD837987B4"><span class="RefLink">41.2-1</span></a>) if no action function
<p>computes the length of the orbit of <var class="Arg">pnt</var> under the action function <var class="Arg">act</var> or <code class="func">OnPoints</code> (<a href="chap41_mj.html#X7FE417DD837987B4"><span class="RefLink">41.2-1</span></a>) if no action function is given.</p>

<p><a id="X8032F73078DF2DDB" name="X8032F73078DF2DDB"></a></p>

<h5>41cpan class"GAPprompt">gap&t<span><span class=GAPinput"Orbitg,12]OnSets);</span>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OrbitLengths</code>( <var class="Arg">G</var>, <var class="Arg">seeds</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>] )</td><td class="tdright">( operation/>div>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OrbitLengths</code>( <var class="Arg">G</var> )</td><td class="tdright">( attribute )</td></tr></table></div>
<ivclass"unc">table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#style='color: green'>8227; OrbitLengths</code>( <var class="Arg">xset</var> )</td><td class="tdright">( attribute )</td></tr></table></div>
<p>computes the lengths of all the orbits of the elements in <var class="Arg">seeds</var> under the action <var class="Arg">act</var> of <var class="Arg">G</var>.</p>

<p>For a permutation group <var class="Arg">G</var>, one may also invoke this as <code class="code">OrbitLengths(<var class="Arg">G</var>)</code>, which returns the lengths of all the orbits of its natural action on the set of points moved by it. For example the group <span class="SimpleMath">\(\langle (1,2,3), (5,6) \rangle\)</span> has the orbit lengths 2 and 3.</p>

<p><a id="X8520E2487F7E98AF" name="X8520E2487F7E98AF"></a></p>

<h5>41.4-6 <span class="Heading">OrbitLengthsDomain</span></h5>

<div classp>apermutation class="">,may  this code=><=ArgG<></code>whichreturnsjava.lang.StringIndexOutOfBoundsException: Range [172, 169) out of bounds for length 428
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OrbitLengthsDomain</code>( <var class="Arg">G</var> )</td><td class="tdright">( attribute )</td></tr></table></div>
classfunc> class="unc"width=100"><tr>java.lang.StringIndexOutOfBoundsException: Range [65, 64) out of bounds for length 229
<p>computes the lengths of all the orbits of <var class="Arg">G</var> on <var class="Arg">Omega</var>.</p>

<> operation is often faster than <code class="func">OrbitLengths</code> (<a href="chap41_mj.html#X8032F73078DF2DDB"><span class="RefLink">41.4-5</span></a>). The domain <var class="Arg">Omega</var> must be closed under the action of <var class="Arg">G</var>, otherwise an error can occur.</p>

<p>For a permutation group <var class="Arg">G</var>, one may also invoke this as <code class="code">OrbitLengthsDomain(<var class="Arg">G</var>)</code>, which returns the length of all the orbits of its natural action on the set of points moved by it.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=Group((1,3,2),(2,4,3));;</span>
classG"gapgt;><spanclass"java.lang.StringIndexOutOfBoundsException: Range [62, 60) out of bounds for length 103
12
<span class="GAPprompt">gap></span> <span class="GAPinput">OrbitLengths(g,Arrangements([1..4],4),OnTuples);</span>
[ 12, 12 ]
<span class=<>returns aof  <arclass="Arg">G</var> on the domain <var class="Arg">Omega</var> (given as lists) under the action <var class="Arg">act</var> or under <code class="func">OnPoints</code> (<a href="chap41_mj.html#X7FE417DD837987B4"><span class="RefLink">41.java.lang.StringIndexOutOfBoundsException: Index 277 out of bounds for length 0
<span class="GAPprompt">gap></span> <span class="GAPinput">OrbitLengthsDomain(g,[1,2,3]);</span>
[ 3 ]
<span class="GAPprompt">gap></span> <span class="GAPinput">OrbitLengthsDomain(g);</span>
[ 3, 3 ]
</pre></div>

<p><a id="X797BD60E7ACEF1B1" name="X797BD60E7ACEF1B1"></a></p>

<h4>41.5 <span

<p>The <em>stabilizer</em> of a point <span class="SimpleMath">\(xspan class"GAPprompt">&t</> class="GAPinput">g:=Group((1,3,2),(2,4,3));;</span>

<p><a id="X7C34EC437EF598BF" name="X7C34EC437EF598BF"></a></p>

<h5>41.5-1 OrbitStabilizer</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OrbitStabilizer</code>( <var class="Arg">G</var>[, <var class="Arg">Omega</var>], <var class="Arg">pnt</var>[, <var class="Arg">gens</var>java.lang.StringIndexOutOfBoundsException: Index 239 out of bounds for length 57
<p>computes the orbit and the stabilizer of <var class="Arg">pnt</var> simultaneously in a single orbit-stabilizer algorithm.</p>

<p>The stabilizer will have <var class="Arg">G</var> as its parent.</p>

<p><a id="X86FB962786397E02" name="X86FB962786397E02"></a><span class=GAPprompt>gt; span class=GAPinput>OrbitsDomaingGF(^,(,,3,(,)(3]<span

<h5>41.5-2 Stabilizer</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; Stabilizer</code>( <var class="Arg">G</var>[, <var class="Arg">Omega</var>], <var class="Arg">pnt</var>[, <var class="Arg">[[;animmutable vectorof 2gt;,
<p


<div class="example"><pre>
java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<span class="GAPprompt">gap></span> <span class="GAPinput">stab:=Stabilizer(g,4);</span>
Group([ (1,3,2) ]<h5>41.-4 OrbitLengthh5>
<span class="GAPprompt">gap></span> <span class="GAPinput">Parent(stab);</span>
Group([ (1,3,2), (2,4,3) ])
</pre></div>

<p>The stabilizer of a set or tuple of points can be computed by specifying an action of sets or tuples of points.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">Stabilizer(g,[1,2],OnSets);</span>
Group([ (1,2)(3,4) ])
<span
Group(())
<span class="GAPprompt">gap></span> <span class="GAPinput">orbstab:=OrbitStabilizer(g,[1,2],OnSets);</span>
rec(
  orbit := [ [ 1, 2 ], [ 1, 3 ], [ 1, 4 ], [ 2, 3 ], [ 3, 4 ],
      4 ]],stabilizer : Group[ 1,2(3,)])  java.lang.StringIndexOutOfBoundsException: Index 55 out of bounds for length 55
<span class="GAPprompt">gap></span> <span class="GAPinput">Parent(orbstab.stabilizer);</span>
Group([ (1,3,2), (2,4,3) ])
</pre></div>

<p>(See Section <a href="chap41_mj.html#X81B8F9CD868CD953"><span class="RefLink">41.2</span></a> for information about specific actions.)</p>

<Thestandard methods for all these actions are an orbit-stabilizer algorithm. For permutation groups backtrack algorithms are used. For solvable groups an orbit-stabilizer algorithm for solvable groups, which uses the fact that the orbits of a normal subgroup form a block system (see <a href="chapBib_mj.html#biBSOGOS">[LNS84]</a>) is used.</p>

<p><a id="X78C3A8568414BC44" name="X78C3A8568414BC44"></a></p>

<h5>41.5-3 OrbitStabilizerAlgorithm</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; OrbitStabilizerAlgorithm</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>, <var class="Arg">blist</var>, <var class="Arg">gens</var>, <var class="Arg">acts</var>, <var class="Arg">pntact</var> )</td><td class="tdright">( operation )</td></tr></table></div>
<p>This operation should not be called by a user. It <p><a id="X8520E2487F7E98AF" name="X8520E2487F7E98AF"><></p>

<p><code java.lang.StringIndexOutOfBoundsException: Index 64 out of bounds for length 63

<p>The <var class="Arg">pntact</var> record may carry a component <var class="Arg">stabsub</var>. If given, this must be a subgroup stabilizing <em>all</em> points in the domain and can be used to abbreviate stabilizer

<p>The <var class="Arg">pntact</var> component also may contain the boolean entry <code class="code">onlystab</code> set to <code class="keyw">true</code>. In this case the <code class="code">orbit</code> component may be omitted from the result.</p>

<p>The argument <var class="Arg">Omega</var> (which may be replaced by <code class="keyw">false</code> to be ignored) is the set within which the orbit is computed (once the orbit is the full domain, the orbit calculation may stop). If <var class="Arg">blist</var> div =f"<class="""< "< f"&;java.lang.StringIndexOutOfBoundsException: Range [120, 119) out of bounds for length 229

pid"name=X7A9389097BAF670D"<><>

41<java.lang.StringIndexOutOfBoundsException: Range [21, 20) out of bounds for length 74

<p><a id="X857DC7B085EB0539" name="X857DC7B085EB0539"></a></p>

<h5>41.6-1 RepresentativeAction</h5>

<">&#; /code( G/[ class="rgjava.lang.StringIndexOutOfBoundsException: Range [180, 179) out of bounds for length 401
<p>computes an element of <var class="Arg">G</var> that maps <var class="Arg">d</var> to <var class="Arg">e</var> under the given action and returns <code class="keyw">fail</code> if no such element exists.</p>


=>java.lang.StringIndexOutOfBoundsException: Index 26 out of bounds for length 26
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=Group((1,3,2),(2,4,3));;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">RepresentativeAction(g,1,3);</spanspan "">></pan<pan class">(,123];<>
(1,3)(2,4)
<span class=""gapgt<span span ">epresentativeActiong13OnPoints)<span>
(1,3)(2,4)
java.lang.StringIndexOutOfBoundsException: Range [6, 5) out of bounds for length 109
(1,2,4)
<span class="GAPprompt">gap></span
fail
<span class="GAPprompt">gap></span> <span class="GAPinput">RepresentativeAction(g,Group((1,2,3)),Group((2,3,4)));</span>
(1,2,4)
<span class="GAPprompt">gap></<54151 java.lang.StringIndexOutOfBoundsException: Index 31 out of bounds for length 31
(43)
<span class="GAPprompt">gap></span> <span class="GAPinput"> RepresentativeAction(g,[1,2,3],[1,2,4],OnTuples);</span>
fail
</pre></div>

<p>(See Section <a href="chap41_mj.html#X81B8F9CD868CD953">java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p>Again the standard method for <code class="func">RepresentativeAction</code> is an orbit-stabilizer algorithm, for permutation groups and standard actions a backtrack algorithm is used.</p>

<p><a id="p>computes the stabilizer var "Arg"</of =Arg"pntvar,thatis  java.lang.StringIndexOutOfBoundsException: Range [126, 125) out of bounds for length 268

<java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0

>a span)span> on domain> java.lang.StringIndexOutOfBoundsException: Range [267, 248) out of bounds for length 712

<p>For an action homomorphism, the operation <code class="func">UnderlyingExternalSet</code> (<a href="chap41_mj.html#X8190A8247F29A5C7"><span class="RefLink">41.12-16</span></a>) will return the external set on <span class="SimpleMath">\(\Omega\)</span> which affords the action.</p>

<p><a id="X78E6A002835288A4" name="X78E6A002835288A4"></a></p>

<>17- span=Heading</spanh5

< classfunc"tablejava.lang.StringIndexOutOfBoundsException: Range [32, 30) out of bounds for length 384
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; ActionHomomorphism</code>( <var class="Arg">xset</var>[, <var class="Arg">"surjective"</var>] )</td><td class="tdright">( function )</td></tr></table></div>
classclass""="<>< ="dleft"><">#;ActionHomomorphism>(<var=Arg"action<var>)/>td class=t">&bsp;java.lang.StringIndexOutOfBoundsException: Range [200, 199) out of bounds for length 230
<p>computes a homomorphism from <var class="Arg">G</var> into the symmetric group on <span class="SimpleMath">\(|\textit{Omega}|\)</span> points that gives the permutation action of <var class="Arg">G</var> on <var class

<poup([ 1,2)(3,) )

<>By  the homomorphism  <ode class"unc></code> is not  surjective (ts <code class="func">Range</code> (<a href="chap32_mj.html#X7B6FD7277CDE9FCB"><span class="RefLink">32.3-7</span></a>) value is the full symmetric group) to avoid unnecessary computation of the image. If the optional string argument <code class="code">"surjective"</code> is given, a surjective homomorphism is created.</p>

<p>The third version (which<panclass="gt< spanjava.lang.StringIndexOutOfBoundsException: Range [51, 50) out of bounds for length 96

<p>(See Section <a href="chap41_mj.html#X81B8F9CD868CD953"><span class="RefLink">41.2</java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=Group((1,2,3),(1,2));;</span>
<span  id="X" name="X78C3A8568414BC44"</</>
<action homomorphism>
<span class="GAPprompt">gap></span> <span class="GAPinput">Image(hom);</spanjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

[ (1,9,13)(2,10,14)(3,7,15)(4,8,16)(5,12,17)(6,11,18)(19,22,23)(20,21,
    ),(,)28()(,10),1)(612(13,)141617,)19,
    21)(20,22)(23,24) ])
<span class="GAPprompt">gap></span> <span class="GAPinput">Size(Range(hom<p>< class=func/java.lang.StringIndexOutOfBoundsException: Range [66, 62) out of bounds for length 532
620448401733239439360000
6
<span class="GAPprompt">gap></span> <span class="GAPinput">hom:=ActionHomomorphism(g,Arrangements([1..4],3),OnTuples,</span>
<span class="GAPprompt">></span> <span class="GAPinput">"surjective");;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">Size(Range(hom)java.lang.StringIndexOutOfBoundsException: Index 2 out of bounds for length 0
6
</pre></div>

<p>When acting on a domain, the operation <code class="func">PositionCanonical</code> (<a href="chap21_mj.html#X7B4B10AE81602D4E"><span class="RefLinkjava.lang.StringIndexOutOfBoundsException: Index 150 out of bounds for length 0

<p><a id="X85A8E93D786C3C9C" name="X85A8E93D786C3C9C"></a></p>

<h5>41.7-2 Action</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><p>The  <var Argjava.lang.StringIndexOutOfBoundsException: Range [39, 38) out of bounds for length 1213
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; Action</code>( <var class="Arg">xset</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>returns the image group of <code class="func">ActionHomomorphism</code> (<a href="chap41_mj.html#X78E6A002835288A4"><span class="java.lang.StringIndexOutOfBoundsException: Index 133 out of bounds for length 0

<p>Notep><id"857DC7B085EB0539"name="X857DC7B085EB0539">/a<p

<p

<p>The following code shows for example how to create the regular action of a group.</p>


<divclass"example"<pre>
<span class="GAPprompt">gap></<spanclass="GAPprompt">gap></span> <span class="GAPinput">g:=Group((1,3,2),(2,4,3));;</span>
< =""gapgt;/pan <spanclass="APinput"ActiongA(g)>
Group([ (1,5,3)(2,6,4), (1,6)(2,5)(3,4) ])
</pre></div>

<p><a id="X86FF54A383B73967" name="X86FF54A383B73967"></a></p>

<h5>41.7-3 SparseActionHomomorphism</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="(,,4)
<div class="func"><table class="func" width="100%"><tr><td class="tdleftfjava.lang.StringIndexOutOfBoundsException: Index 4 out of bounds for length 4
<p><code class="func">SparseActionHomomorphism</code> computes the action homomorphism (see <code class="func">ActionHomomorphism</code> (<a href="chap41_mj.html#X78E6A002835288A4"><span class="RefLink">41.7-1</(11,,)

<p>If <var class="Arg">G</var> acts on a very large domain not surjectively this may yield a permutation image of java.lang.StringIndexOutOfBoundsException: Range [0, 127) out of bounds for length 117

<p>The operation <code class="span> spanclass="APinput RepresentativeActiong,1,,],12,,OnTuples)</ code""></ode is -stabilizeralgorithm,  permutationgroups and standard actions a backtrack algorithm is used.</p>

<p>The operation <code class="func">SortedSparseActionHomomorphism</code> in


<div class="example"><pre>
<java.lang.StringIndexOutOfBoundsException: Range [6, 5) out of bounds for length 100
Group([ [ [ Z(3), Z(3) ], [ 0*Z(3), Z(3) ] ] ])
<spanp>java.lang.StringIndexOutOfBoundsException: Range [17, 16) out of bounds for length 284
<span class="GAPprompt">gap></span> <span class="GAPinput">Image(hom);</span>
Group([ (2,3)(4,9,6,7,5,8) ])
<span class="GAPprompt">gap></span> <span class="GAPinput">hom:=SparseActionHomomorphism(h,[Z(3)*[1,0]],OnRight);;</span>
<span class="GAPprompt">gap></""</a></java.lang.StringIndexOutOfBoundsException: Range [62, 61) out of bounds for length 62
Group([ (1,2,3,4,5,6) ])
</pre></div>

<p><a id="X7FED50ED7ACA5FB2" name="X7FED50ED7ACA5FB2"></a></p>

<h4>41.8 <span class="Heading">Action of a group on itselfdiv class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#8227; ActionHomomorphism</code>( < java.lang.StringIndexOutOfBoundsException: Range [27, 26) out of bounds for length 426

<p>Of particular importance is

<<id="X784D417D87F4E58D name="784">/a</>

<h5>41.8-1 FactorCosetAction</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="
<div class="unc"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#n style='color: green'>8227; FactorCosetAction</code>( <var class="Arg">G</var>, <var class="Arg">L</var> )</td><td class="tdright">( operation )</td></tr></table></div>
<p>This command computes the action of the group << class="APprompt"gapgt;<span  class"APinputhom:ActionHomomorphism(gArrangements([.4],),nTuples);</pan>


<divclass=example"<>
<span class="GAPprompt">gap></span> <java.lang.StringIndexOutOfBoundsException: Range [0, 44) out of bounds for length 6
15
<span class="GAPprompt">gap></span> <span class="GAPinput">FactorCosetAction(g,u);</span>
[ (1,2,3,4,5), (1,2) ] -> [ (1,4,7,10,13)(2,5,8,11,14)(3,6,9,12,15),\
  ,14 java.lang.StringIndexOutOfBoundsException: Index 38 out of bounds for length 38
<span class="GAPprompt">gap></span> <span class="GAPinput">StructureDescription(Range(last));</span>
"S5"
<span class="GAPprompt">gap></span> <span class=java.lang.StringIndexOutOfBoundsException: Index 51 out of bounds for length 1
<span class="GAPprompt">gap></span> <span class="p>When java.lang.StringIndexOutOfBoundsException: Range [15, 14) out of bounds for length 624
120
</pre></div>

<p>The correspondence of points with cosets will, for performance reasons, depend on the method used. It is not guaranteed that it will be the same as used by <code class="code">RightTransversal</code> or <code class="code">RightCosets

<><a id=" java.lang.StringIndexOutOfBoundsException: Range [35, 33) out of bounds for length 62

<h5""table=""100"<>td class=">code="java.lang.StringIndexOutOfBoundsException: Range [93, 91) out of bounds for length 216

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; RegularActionHomomorphism</code>( <var class="Arg">G</var> )</td><td class="tdright">( attribute )</<p>returns the image group of <code class="func">ActionHomomorphism</code> (<a href="chap41_mj.html#X78E6A002835288A4"><span class="RefLink">41.7-1</span></a>) called with the same parameters.</p>
<p>returns an isomorphism from <var class="Arg">G</var> onto thejava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p><a id="X835317A7847477D4" name="X835317A7847477D4"></a></p>

<>.83  </h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleftspan class="GAPprompt"gap>span> < =GAPinput">ctiong,sListg)OnRight);</span>
<Letvar class="Arg">G</var> be a group and <span class="SimpleMath">\(\textit{M=AgeqtextitN\/be  ofa  normalunder< classArg">G/var> such  java.lang.StringIndexOutOfBoundsException: Range [204, 203) out of bounds for length 1329

<p>Note: If only matrices for the action are needed, <code class="func">LinearActionLayer</code> (<a href="chap45_mj.html#X7C2135B98732BBC3"><span class="RefLink">45.14-3</span></a>) might be faster.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=Group((1,8,10,7,3,5)(2,4,12,9,11,6),</pre></div>
<java.lang.StringIndexOutOfBoundsException: Range [101, 5) out of bounds for length 110
<span class="GAPprompt">gap></span> <span class="GAPinput">c:=ChiefSeries(g);;List(c,Size);</span>
[java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<span class="GAPprompt">gap<541.3SparseActionHomomorphism<h5>
true
<span class="GAPprompt">gap></span> <span class="java.lang.StringIndexOutOfBoundsException: Index 59 out of bounds for length 0
<span class="GAPprompt">gap></span> <span class="GAPinput">a:=AbelianSubfactorAction(g,c[3],c[4]);</span>
[ [ (1,8,10,7,3,5)(2,4,12,9,11,6), (1,9,5,6,3,10)(2,11,12,8,4,7) ] ->
    [ <an immutable 2x2 matrix over GF2>,
      <an immutable 2x2 matrix over GF2> ],
  MappingByFunction(  ()java.lang.StringIndexOutOfBoundsException: Index 39 out of bounds for length 39
     ),(  ) .. end, function( r ) .. end,
  Pcgs([ (2,9,3,8)(4,11,5,10), (1,6,12,7)(4,10,5,11) ]) ]
<span class="GAPprompt">gap></span> <span <span class="GAPprompt">gap></span> <span classnot surjectively this may yield a permutation  imageof substantially smaller degree than by action on the whole domain.</p>
java.lang.StringIndexOutOfBoundsException: Range [6, 5) out of bounds for length 49
  &java.lang.StringIndexOutOfBoundsException: Range [0, 5) out of bounds for length 0
=>/>spanGjava.lang.StringIndexOutOfBoundsException: Range [61, 60) out of bounds for length 79
3
<span class="GAPpromptspanclass=G&<span span class="GAPinput">h:=Group(Z(3)*[[[1,1],[0,1]]]);</span>
(2,9,3,8)(4,11,5,10)
<span class="GAPprompt">gap></span> <span class=
true
false
</pre><

<p><a id="X807AA91E841D132B" name="X807AA91E841D132B"></a></p>

<h4>41.9 <span class="Heading">Permutations Induced by div class="func"><table class="func" width="100%"><tr><td class class">8227java.lang.StringIndexOutOfBoundsException: Range [119, 118) out of bounds for length 279

< element is java.lang.StringIndexOutOfBoundsException: Range [67, 66) out of bounds for length 209

<></a>p>

<91 java.lang.StringIndexOutOfBoundsException: Range [17, 16) out of bounds for length 56

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; Permutation</code>( <var class="Arg">g</var>, <var class="Arg">Omega</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>java.lang.StringIndexOutOfBoundsException: Index 2 out of bounds for length 2
<div class="func"><table class="func" width""
<p permutation domain <var class=A"Omega</ar> ( listof objects that are permuted). If an external set <var class="Arg">xset</var> is given, the permutation domain is the <code class="func">HomeEnumerator</code> (<a href="chap41_mj.html#X86A0CC1479A5932A"><span class="RefLink">41.12-5</span></a>) value of this external set (see Section <a href="chap41_mj.html#X7FD3D2D2788709B7"><span class="RefLink">41.12</span></a>).<span class="GAPprompt">gap></span> <span class="GAPinput">Size(Image());/span

<p>If <var class="Arg">g</var> does not leave the domain invariant, or does not map the domain injectively then <code class="keyw">fail</code> is returned.</p>

< =java.lang.StringIndexOutOfBoundsException: Range [29, 27) out of bounds for length 62

<41.2 h5>

<div class="func"><table class="func" width="java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<p>computes the permutation thatdiv java.lang.StringIndexOutOfBoundsException: Range [12, 10) out of bounds for length 282


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">p>Let <var class="Arg">G</var> be a group and <span class="SimpleMath{ \java.lang.StringIndexOutOfBoundsException: Range [98, 97) out of bounds for length 1329
(,)3,48
<span class="GAPprompt">gap></span> <span class="GAPinput">Permutation((1,2,3)(4,5)(6,7),[4..7]);</span>
(1,2)(3,4)
<classGAPprompt>>/><java.lang.StringIndexOutOfBoundsException: Range [45, 44) out of bounds for length 114
(1,2)
</pre></div>

<p><a id="X80AF6E0683CA7F14" name="X80AF6E0683CA7F14"></a></p>

<h5>41.9-3 Cycle</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; Cycle</code>( <var class="Arg">g</var>, <var class="Arg">Omega</var>, <var class="Arg">pnt</var>[, <var class="Arg">act</var>] )</td><td class="tdright">( function )</td<pan class="GAPprompt">gap><span<span class="GAPinput">c:=ChiefSeries(g);;List(c,Size);</span>
<p>returns a list of the points in<span class=GAPprompt"gap></span> <span class="GAPinput">a:=AbelianSubfactorAction(g,c[3],c[4]);</span>

<p><a id="X7F559E897B333758" name="X7F559E897B333758"></a></p>

<h5>41.9-4 CycleLength</h5>

<div class="func"><table class="func" width="100%"><tr><td java.lang.StringIndexOutOfBoundsException: Index 61 out of bounds for length 39
<p>returns the length of the cycle of <var class="Arg">pnt</var> under the action of the element <var class="Arg">g</var>.</p>

<p><a id="X7F3B387A7FD8AE5E" name="X7F3B387A7FD8AE5E"Group&tan immutable 2x2 matrix over GF2>,

<h5>41.9-5 Cycles</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; Cycles</code>(<span class="GAPprompt""gapgt</pan> <span class="GAPinput>Size(at)</
< theaction ofthe  <varclass=""rg>g/var>.<p>>

<p><a id="X83040A6080C2C6C6" name="X83040A6080C2C6C6"></a></p>

<h5>41.9-6 CycleLengths</h5>

<div classjava.lang.StringIndexOutOfBoundsException: Index 4 out of bounds for length 4
<p>returns the lengths of </pre></div>


<div class="p><a id="X807AA91E841D132"nameX807AA91E841D132B/<java.lang.StringIndexOutOfBoundsException: Range [62, 61) out of bounds for length 62
<span class="GAPprompt">gap></span> <ons Inducedby Elements Cycles</span></h4>
[ 4, 5 ]
<span class=<>   permutation image  elementis needed,it  notbe worth to the action homomorphism, the following operationsyield the permutationimage and cycles  a./p
2
<><idjava.lang.StringIndexOutOfBoundsException: Range [28, 27) out of bounds for length 62
[ [ 4, 5 ], [ 6, 7 ] ]
<span class="GAPprompt">gap></span> <span class="GAPinput">CycleLengths((1,2,3)(4,5java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
 ,2]
</pre></div>

p>aid=X87FDA6838065CDCB=java.lang.StringIndexOutOfBoundsException: Range [53, 52) out of bounds for length 62

<h5>41.9-7 <span class="Heading">CycleIndex</span></h5>

idth=100%>><td =tdleft"<class=func"&#;CycleIndex<> < =Arg">g</var>, < class=""Omega</var[<var "Arg">act<var> )/><dclass="tdright"(  )</td><tr></><div
<div class="func"><table class="func" java.lang.StringIndexOutOfBoundsException: Index 41 out of bounds for length 0
<p>The <em>cycle index</em> of a permutation <var class=java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<class=">[
z(<var class="Arg">g</var>) = s_1^{{c_1}} s_2^{{c_2}} \cdots s_n^{{c_n}}
java.lang.StringIndexOutOfBoundsException: Index 141 out of bounds for length 6

<p>where <span class="SimpleMath">\(c_k

<The <>cycle<em>of agroup < class="rg>G</var> isdefined <p

<p class="center">\[
Z(<var class="Arg">G</var>) = \left( \sum_{{g \in <var class="Arg">G</var>}} z(g) \right) / |<var class="Arg">G</var>| .
\]</p>

<p>The indeterminates used by <code class="func">CycleIndex</code> are the indeterminates <span class="SimpleMath">\(1\)</span> to <span java.lang.StringIndexOutOfBoundsException: Index 139 out of bounds for length 5


<div class="example"><pre>
<java.lang.StringIndexOutOfBoundsException: Index 5 out of bounds for length 0
S_4(6c =1/[2^3]S(3java.lang.StringIndexOutOfBoundsException: Index 22 out of bounds for length 22
<span class="GAPprompt">gap></span> <span class="GAPinput">CycleIndex(<p>a of the points inthe cycle  class="Arg">pnt<var> theoftheelement<class="Arg"gvar<p>
1/x_1^+/x_1^2x_2^21*_1^2*x_4+1/4*x_2^3+1/3*x_3^2
</pre></div>

<p><a id="X850A84618421392A" name="X850A84618421392A"></a></p>

<4>41.10 <span ="Heading"Testsforspan><h4

<paid"7915750851828CB"name=X79B15750851828CB/<p

<h5>41.10-1 <span class="Heading">IsTransitive</span></h5>

<div class="func"><table class="func" class="">< class=f width="100%><tr>td =tdleft"><code class="func">&#8227; Cycles</code>( <var class="Arg">g</var>, <var class="Arg">Omega</var>[, <var class="Arg">act</var>] )</td><td class="tdright">( function )</td></tr></table></div>
<div class="func"><table java.lang.StringIndexOutOfBoundsException: Range [0, 30) out of bounds for length 28
<class=func"<table classfunc"width=100"<><td class=t"codeclass="">&8227 IsTransitive</code> var "rg">set/var )/>td class="dright">( property )</td></tr></table></div>
<p>returns <code class="keyw">true</code>if the action impliedby the argumentsis transitive, or code java.lang.StringIndexOutOfBoundsException: Range [111, 110) out of bounds for length 145

<iv"">pre

<p>For a permutation group <var class="Arg">G</var>, one may also invoke this as <code class="code">java.lang.StringIndexOutOfBoundsException: Index 108 out of bounds for length 8


< class=""<>
<span class= [ ,  ,[ ,7 ] java.lang.StringIndexOutOfBoundsException: Index 22 out of bounds for length 22
<span class="GAPprompt">gap></span> <span class="GAPinput">IsTransitive( G, [ 2 .. 4 ] );</span>
true
<span class="GAPprompt">gap></span> <span class="GAPinput">IsTransitive( G, [ 2, 3 ] );   # G does not act
false
<span class="GAPprompt">gap></span> <span class="GAPinput">IsTransitive( G, [ 1 ..<54197<spanclass=Heading"/pan></h5>
alse
< class"APprompt"gap&;/span><class="GAPinputIsTransitive( )  # G istransitive on[  .]/pan>
true
<spanclass=GAPprompt"g;/<span classG"IsTransitive SL(, 3), NormedRowVectors( GF(3)^2 ) );</span>
false
<span class="java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
true
</pre></div>

<p><a id="X8295D733796B7A37" name="X8295D733796B7A37"></a></p>

<h5>41.10-2 <span class="Heading">Transitivity</span></h5>

<divclass=unc>table ="func""%>tr>td class"tdleft"<code class="func>#8227 Transitivity/code> var =Arg"><var> <var class="Arg"</var>[ var class=A">ens<var, var "">acts</][,< class""act/var])/< class"">(nbspoperationnbsp;<td>/>/><div>
<div class="func"><table class="func" width="java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<<code class="func">&8227 Transitivity/code> varclass=Arg"xset<><td>< class="tdright"(nbsp;attributenbsp;<td>/tr</table>/>
<p>returns the degree <span class="SimpleMath">\(k\)</span> (a non-negative integer) of transitivity of the action implied by the arguments, i.e. the largest integer <span class="SimpleMath">\(k\)</span> such that the action is <span class="SimpleMath">\(k\)</span>-transitive. If the action java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p>An action is <em><span class="SimpleMath">\(k\)</span>-transitive</em> if every <span class="SimpleMath">\(k\)</span>-tuple of points can be mapped simultaneously to every other <span class="SimpleMath">\(k\)</span>-tuple.</p>

<java.lang.StringIndexOutOfBoundsException: Range [37, 2) out of bounds for length 437


<div class="example"><pre>
<span class="GAPprompt">java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<span class="GAPprompt">gap></span> <span class="GAPinput">IsTransitive(g,[1..5]);</span>
false
<span class="GAPprompt">gap></span> <span class="GAPinput">Transitivity(g,[1..4]);</span>
2
<span class="GAPprompt">gap></span> <<span class="GAPprompt">gap></span> <span class="GAPinput">g:=TransitiveGroup(6,8);</span>
2
</pre></div>

<p><a id="X8166A6A17C8D6E73" name="X8166A6A17C8D6E73"></a></p>

<h5>41.10-3 <span class="Heading">RankAction</span></h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; RankAction</code>( <var class="Arg">G</var>, <java.lang.StringIndexOutOfBoundsException: Index 149 out of bounds for length 0
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code h44110 <class="eading">TestsforActions<><h4>
<p>java.lang.StringIndexOutOfBoundsException: Index 10 out of bounds for length 0


<div class="example"><pre>
<class=GAPprompt">gapg<span> <spanclass="GAPinput"RankAction(g,Combinations([1..4],2),OnSets);</span>
4
</pre></div>

<p><a id="X7B77040F8543CD6E" name="X7B77040F8543CD6E"></a></pdiv "">tableclass=func "%><>tdclass=t"<code java.lang.StringIndexOutOfBoundsException: Range [86, 85) out of bounds for length 219

<h5>41.10-4 <<div class="func"table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#8227; IsTransitive</code>( <var class="Arg">xset</var> )</td><td class="tdright">( property )</td></tr></table></div>

< ""<tableclass="funcwidth="00"<tr><class="">code class="func">‣ IsSemiRegular</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>] )</td><td class="tdright">( operation )</td></tr></table></div>
<ivclass=f"<table class"func" width="%><>tdclass""<ode =""&8227 IsSemiRegular<code>( <var class="Arg">G</var> )</td><td class="tdright">( property )</td></tr></table></div>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="funcjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<p>returns <code class="keyw">true</code> if the action implied by the arguments is semiregular, or <code class="keyw">falsespan class="GAPprompt">gap></span> <span class="GAPinput">G:= Group( (2,3,4), (2,3) );;</span>

<p>An action is <em>semiregular</em> if the stabilizer of <spanclass">gap><span,[2 3 ]); G  notacton[ ,3]</span

<p>For a permutation group <var class="Arg">G</var>, one may also invoke this as <code class="code">IsSemiRegular(<var class="Arg">G</var>)</code>, which tests whether the group is semiregular with respect to false

<p><a id="X7CF02C4785F0EAB5" name="X7CF02C4785F0EAB5"></a></p>

<h5>41.10-5 <span class="Heading">IsRegular</span></h5>

<div class="func"><table class="func" width="100%"><tr
< "">tableclassf"width=100%><r>td ="tdleft><<codeclass="func"‣IsRegular</code>( <var class="Arg">G</var> )</td><td class="tdright">( property )</td></tr></table></div>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; IsRegular</
<p>returns <code class="keyw">true</code> if the/pre></div>

<p>An action is <em>java.lang.StringIndexOutOfBoundsException: Index 21 out of bounds for length 0

<p>For a permutation group <var class="Arg">G</var>, one may


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">IsSemiRegular ="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#8227; Transitivity</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>[, <var class=""gens/, var "">acts<var[  "rg"act/ar>)/td><dclass=tdright"(&bsp;operationn;)<td<tr>table><>
true
<span class="GAPprompt">gap></span> <span class="GAPinput">IsRegular(g,Arrangements([1..4],3),OnTuples);</span>
false
</pre<div class=func"""width=100%>tr>td class=""code class="unc">#8227 Transitivity</code>( <var class="Arg">xset</var> )</td><td class="tdright">( attribute )</td></tr></table></div>

<p><a id="X7CB1D74280F92AFC" name="X7CB1D74280F92AFC"></a></p>

<h5>41.10-6 <span class="Heading">Earns</span></h5>

<div class="func"><table class="func" width="100<a  group<var class"rg>/var> may also invoke thisas<code class=""Transitivity(<var class="Arg">G</var>)</code>, which returns the degree of transitivity of the group with respect to its natural action on the set of points moved by it. For example the group <span class="SimpleMath">\(\langle (2,3,4),(2,3) \rangle\)</span> is 3-transitive on the set <span class="SimpleMath">\(\{2, 3, 4\}\)</span>.</p>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; Earns</code>( <var class="Arg">xset</var> )</td><td class="tdright">( attribute )</td></tr></table><
<p>returns a list of the elementary abelian regular (when acting on <var java.lang.StringIndexOutOfBoundsException: Range [0, 78) out of bounds for length 1

<p>java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 1

<p><a id="X84C19AD68247B760" name="X84C19AD68247B760"></a></p>

<h5>41.10-7 <span class="Heading">p><a id="X8166A6A17C8D6E73" name="X8166A6A17C8D6E73/p

<div class="func"><table<5>41.-3<span class="eading">RankAction</span></h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
class="func"<table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#style='color: green'>8227; IsPrimitive</code>( <var class="Arg">xset</var> )</td><td class="tdright">( property )</td></tr></table></div>
<p>eturns <code class="keyw">true</code> if the action implied by the arguments is primitive, or <code class="keyw">false</code> otherwise.</p>

<action<primitive>  is s code"unc"IsTransitivecode (=chap41_mj..html#X79B15750851828CB"<span class"RefLink>4110-1/span>/a) and the action admits no nontrivial block systems. See <a href="chap41_mj.html#X7E9D3D0B7A9A8572"><span class="RefLink">41.11</span></a> for the definition of block systems.</p>

<p>For a permutation group <var class="Arg">G</var>, one may also invoke this as <code class="codespan class"APprompt>gapg;/panjava.lang.StringIndexOutOfBoundsException: Range [45, 44) out of bounds for length 113

<p>For an explanation of the meaning of all the inputs, please refer to  <a href="chap41_mj.html#X83661AFD7B7BD1D9"><span class="RefLink">41.1</span></a>.</p>

<p><em>Note:</em> This operation does not tell whether a matrix group is primitive in the sense of preserving a<541.-4 <span class"Heading">IsSemiRegular/span>/h5>


< class="example">pre
<span class="GAPprompt">gap></span> <span class="GAPinput">IsPrimitive(g,Orbit(g,(1,2)(3,4)));</span>
true
</pre></div>

<p><a id="X7E9D3D0B7A9A8572" name="X7E9D3D0B7A9A8572"></a></p>

<h4>41.11 <span class="Heading">Block Systems</span></h4>

<p>A <em>block system</em> (system of imprimitivity) for the action pAnaction is <em>semiregular</em> if the stabilizer of each point is the identity.</p>

<p><a id="X84FE699F85371643" name="X84FE699F85371643"></a></p>

<h5>41.11-1 <span class="Heading">Blocks</span></h5>

<div="func"<table class"100>><td class="tdleft"><code class="func">‣ Blocks</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>[, <var class="Arg">seed</var>][, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>] )</td><td class="tdright">( operation )</td></tr></table></div>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="<divclass"func"< "unc" width="100%"><tr><td class="tdleft"><code class="func">‣ IsRegular</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>] )<divclass="func"<table"func"width"100"<tr><td class="tdleft"><code class="func">‣ IsRegular<code> varclass"Arg"Gvar <td>tdclass=tdright"(nbsp;roperty /
<p>computes a block system for the transitive (see <code class="func">IsTransitive</code> (<a href="chap41_mj.html#X79B15750851828CB"><span class="RefLink">41.10

<p>The result is undefined if the action is not transitive.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=TransitiveGroup(8,3);</span>
E(8)=2[x]2[x]2
<span class="GAPprompt">gap></span> <span class="GAPinput">Blocks(g,[1..8]);</span>
[  1, 8] [2  ,[4  ],[6 7]]
<span class="GAPprompt">gap></span> <span class="GAPinput">Blocks(g,[1..8],[1,4]);</span>
[ [ 1, 4 ]java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
/div>

<java.lang.StringIndexOutOfBoundsException: Range [6, 2) out of bounds for length 114

<p><a id="X79936EB97AAD1144" name="X79936EB97AAD1144"></a></p>

<h5>41.11-2 <span class="Heading">MaximalBlocks</span></h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; MaximalBlocks</code>( <var class="Arg">G</var>, <var h5>110- span class="Earns/span></h5>
<>[, <var class="Arg">seed</var>] )</td>td =t>(nbsp; )/d/tr>/table>/>
<p>returns a block system that is maximal (i.e., blocks are maximal with respect to inclusion) for the transitive (see <code class="func">IsTransitive</code> (<a href="chap41_mj.html#X79B15750851828CB"><span class="RefLink">41.10-1</span></a>)) action of <var class="Arg">G</var> on <var class="Arg">Omega</var>. If <var class="Arg">seed</var> is given, a block system is computed in which <var class="Arg">seed</var> is a subset of one block.</p>

<p>The result is undefined if the action is not transitive.</p>


<div class="example"><pre>
<spanh5>.07<span ="eading">IsPrimitive/pan<h5>
[ [ 1,
</pre></div>

<p><a id="X7941DB6380B74510" name="X7941DB6380B74510"></a></p>

java.lang.StringIndexOutOfBoundsException: Index 131 out of bounds for length 74

<java.lang.StringIndexOutOfBoundsException: Range [174, 4) out of bounds for length 356
< class="unc>< class"func" width"%>tr< class="tdleft>code class="func"&8227 RepresentativesMinimalBlockscode>( <var class">xset<var>)<td<tdclass=tdright>(&bsp;ttribute <td</</table><div
<p>computes a list of block representatives for all minimal (i.e blocks are minimal with respect to inclusion) nontrivial block systems for the transitive (see <code class="func">IsTransitive</code> (<a href="chap41_mj.html#X79B15750851828CB"><span class="RefLink">41.10-1</span></a>)) action of <var class="Arg">G</var> on <var class="Arg">Omega</var>.</p>

<p>The result is undefined if the action is not transitive.</p>


< class=example"
<span class="GAPprompt">gap></span> <span class="GAPinput">RepresentativesMinimalBlocks(g,[1..8])
[ 1 2 , ,3]  ,4 ]  1,5][1 [1 7]java.lang.StringIndexOutOfBoundsException: Index 61 out of bounds for length 61
  [ 1, 8 ] ]
//>

<p><a id="X835658B07B28EF3B" name="X835658B07B28EF3B"></a></p>

<h5>41.11-4 AllBlocks</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code true
<p>computes a list of representatives of all block systems for a permutation group <var class="Arg">G</var> acting transitively on the points moved by the group.</p>

<p>Each representative in the returned list is sorted and contains the smallest point moved by <var class="Arg"<span class"eading"BlockSystems<span><4>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">AllBlocks(g)<p>a id="X84FE699F85371643" name="X84FE699F85371643"></a></p>
[[1, 8,[ ,,  ],[,4,5,8 ],   ,8] [1  ,
  [ 1, 3, 5, 7 ], [ 1, 3, 4, 6 ], [ 1, 5 ], [ 1, 2, 5, 6 ], [ 1, 2 ],
  [2 4,7 ],[1 4] [ ,7 ] [1   java.lang.StringIndexOutOfBoundsException: Index 48 out of bounds for length 48
</pre></div>

<p>The stabilizer of a block can be computed via the action <code class="func">OnSets</code> (<a href="chap41_mj.html#X85AA04347CD117F9"><span class="RefLink">41.2-4</span></a>):</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">Stabilizer(g,[1,8],OnSets);</span>
Group[ 1,)23(,5)(,)]
</pre></div>

<p>If <code class="code">bs</code> is a partition of the action domain, given as a set of sets, the stabilizer under the action <code class="func">OnSetsDisjointSets</code> (<a href="chap41_mj.html#X7E23686E7A9D3A20"><span class="RefLink">41.2-8</span></a>) returns the largest subgroup which preserves <code class="code"


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class8=[]2]java.lang.StringIndexOutOfBoundsException: Index 14 out of bounds for length 14
<span class="GAPprompt"> [ 1, 8 ], [ 2, 3 ], [ 4, 6, ]]
<span class="GAPprompt">gap></span> <span class="GAPinput">Stabilizer(g,bs,OnSetsDisjointSets);</span>
[(,) (,6) (58,(2,) 34)5,)1,4),
  1,,48(,37)
</pre></div>

<p><a id="X7FD3D2D2788709B7" name="X7FD3D2D2788709B7"></a></p>

<h4>41.12 <span class="Heading">External Sets</span></h4>

<>When groupactions, sometimes theconcept a <em><span class="">\(\)/span>-set<em is used.This  aset <class"impleMath">\(\Omega\)</span> endowed   of<class=SimpleMath>G<span>.Theelementsthe<pan =>(\/>set are  sameas of <class="SimpleMath">(Omega\)/,however  andequivalence class=S"(G)/span>-sets do not only consider the underlying domain<span class=SimpleMath"\\Omega\<span>but the group  as well./p>

<p>This concept is implemented in <strong class="pkg">GAP</strong> via <em>external sets</em>.</p>

<p>The constituents of an external set are stored in the attributes <code class="func">ActingDomain</code> (<a href="chap41_mj.html#X7B9DB15D80CE28B4"><span class="RefLink">41.12-3</span></a>), <code class="func">FunctionAction</code> (<a href="chap41_mj.html#X86153CB087394DC1"><span class="RefLink">41.12-4</span><<div class=func">table =unc =%>>td ">codeclass""&#8227 /> <class"rg><var[,java.lang.StringIndexOutOfBoundsException: Range [158, 157) out of bounds for length 255

<p>Most operations for actions are applicable as an attribute for an external set.</p>

<p>The most prominent external subsets are orbits, see <code class="func">ExternalOrbit<<>The result is undefined if the action is not transitive.</p>

<p>Many subsets of a group, such as conjugacy classes or cosets (see <code class="func">ConjugacyClass</code> (<a href="chap39_mj.html#X7B2F207F7F85F5B8"><span class="RefLink">39.10-1</span></a>) and <code class="func">RightCoset</code><span class="GAPprompt">gap></span> <span class="GAPinput">MaximalBlocks(g,[1..8]);</span>

<p>External sets also are implicitly underlying action homomorphisms, see <code class="func">UnderlyingExternalSet</code> (<a href="chap41_mj.html#java.lang.StringIndexOutOfBoundsException: Index 164 out of bounds for length 62

<p><a id="X8264C3C479FF0A8B" name="X8264C3C479FF0A8B"></a></p>

<4112- IsExternalSet<h5>

< "">table class=func"width=%"><tr<td class="tdleft"><code class="func">&#8227; IsExternalSet</code>( <var class="Arg">obj</var> )</td><td class="tdright">( category )</td></tr></table></div>
<p>An <em>external set</em> specifies a group action <span class="SimpleMath">\(\mu: \Omega \times G \mapsto \Omega\)</span> of a group <span class="SimpleMath">\(G\)</span> on a domain <span class="SimpleMath">\(\Omega\)</span>. The external set knows the group, the domain and the actual acting function. Mathematically, an external set is the set <span class="SimpleMath">\(\Omega\)</span>, which is endowed with the action of a group <span class="SimpleMath">\(G\)</span> via the group action <span class="SimpleMath">\(\mu\)</span>. For this reason <strong class="pkg"java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p><a id="X7C90F648793E47DD" name="X7C90F648793E47DD"></a></p>

<h5>41.12-2 ExternalSet</h5>

<=">/[  "java.lang.StringIndexOutOfBoundsException: Range [194, 193) out of bounds for length 339
<p>creates the external set for the action <var class="Arg">act</var> of <var class="Arg">G</var> on <var class="Arg">Omega</var>. <var class="Arg">Omega</var> can be either a proper set, or a domain which is represented as described in <a href="chap12_mj.html#X7BAF69417BB925F6"><span class="RefLink">12.4</span></a> and <a href="chap30_mj.html#X8050A8037984E5B6"><span class="RefLink">30</span></a>, or (to use less memory but with a slower performance) an enumerator (see <code class="func">Enumerator</code> (<a href="chap30_mj.html#X7EF8910F82B45EC7"><span class="RefLink">30.3-2</span></a>) ) of this domain.</p>

<p>The result is undefined if <var class="Arg">G</var> does not act on <var class="Arg">Omega</var>.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">g:=Groupjava.lang.StringIndexOutOfBoundsException: Index 70 out of bounds for length 12
<span class="GAPprompt">gap></span> <span class="GAPinput">e:=ExternalSet(g,[1..4]);</span>
&;xset1  , ]>
<span class="GAPprompt">gap></span> <span class="GAPinput">e:=ExternalSet(g,g,OnRight);</span>
<xset:[ (), (2,3,4), (2,4,3), (1,2)(3,4), (1,2,3), (1,2,4), (1,3,2),
  (1,34) (1,3)2,,, (,,2, (,,) (,4)2)&;
<span class="GAPprompt">gap></span> <span class="GAPinput">Orbits(e);</span>
[ [ (), (1,2)(3,4), (1,3)(2,4), (1,4)(2,3), (2,4,3), (1,4,2),
      (1,2,3), (1,3,4), (2,3,4), (1,3,2), (1,4,3), (1,2,4) ] ]
</pre></div>

<p><a id="X7B9DB15D80CE28B4" name="X7B9DB15D80CE28B4"></a></p>

<h5>41.12-3 

< >" ="00"<r><td class="dleftcodeclass="">#8227; </>(< class"">xset/ar )/><d="dright"(nbsp&;)</td><table<>
<p>This attribute returns the group with which the external set <var class="Arg">xset</var> was defined.</p>

<p><a id="X86153CB087394DC1" name="X86153CB087394DC1"></a></p>

<h5>41.12-4 FunctionAction</h5>

<div class="func"><table class="func" width="100%"><tr><td class="java.lang.StringIndexOutOfBoundsException: Index 69 out of bounds for length 23
<p>is the acting function with which the external set <var class="Arg">xset</var> was defined.</p>

<p><a id="X86A0CC1479A5932A" name="X86A0CC1479A5932A"></a></p>

<h5>41.12-5 HomeEnumerator</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; HomeEnumerator</code>( <var class="Arg">xset</var> )</td><td class="tdright">( attribute )</td></tr></table></div>
<p>returns an enumerator of the action domain with which the java.lang.StringIndexOutOfBoundsException: Index 63 out of bounds for length 0


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">ActingDomain(e);</span>
Group([ (1,2,3), (2,3,4) ])
<span class="GAPprompt">gap></span> <span class="GAPinput">FunctionAction(e)=p>The most prominent external subsets are orbits, see <code class="func">ExternalOrbit.span =RefLink>41.29span>/a)<p
truep subsets of a group such  conjugacy (seeee<code class="func"ConjugacyClass<code> (<a href="chap39_mj.html#X7B2F207F7F85F5B8"><span class="RefLink">39.10-1</span></a>) and <code class="func">RightCoset</code> (<a href="chap39_mj.html#X8412ABD57986B9FC"><span class="RefLink">39.7-1</span></a>)) are implemented as external orbits.</p>
<span class="GAPprompt">gap></span> <span class="GAPinput">HomeEnumerator(e);</span>
[ (), (2,3,4), (2,4,3), (1,2)(3,4), (1,2,3), (1,2,4), (1,3,2),
  (1,3,4), (1,3)(2,4), (1,4,2), (java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
</pre></div>

<p><a id="X879DE63C7858453C" name="X879DE63C7858453C"></a></p>

<h5>41.12-6 IsExternalSubset</h5>

 f"width100"trtd =tdleft=func"&8227 IsExternalSubset<code>( <var class="Arg">obj</var> )</td><td class="tdright">( representation )</td></tr></table></div>
<java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p><a id="X87D1EA1486D86233" name="X87D1EA1486D86233"></a></p>

<h5>41.12-7 ExternalSubset</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; ExternalSubset</code>( <var class="Arg">G</var>, <var var can    set,ora  represented   achap12_mjhtmlX7BAF69417BB925F6> ">.<> href=java.lang.StringIndexOutOfBoundsException: Range [341, 340) out of bounds for length 618
<p>java.lang.StringIndexOutOfBoundsException: Index 13 out of bounds for length 0

<p>The result is undefined if <var class="

<p><a id="X7E081F568407317F" name="X7E081F568407317F"></a></p>

.8 IsExternalOrbit</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; IsExternalOrbit</code>( <var class="Arg">obj</var> )</td><td class="tdright">( representation )</td></tr></table></div>
<p>An external orbit is an external subset consisting of one orbit.</p>

<p><a id="X7FB656AE7A066C35" name="X7FB656AE7A066C35"></a></p>

<h5>41.12-9 ExternalOrbit</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; ExternalOrbit</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>, <var class="Arg">pnt</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>], <var class      1)1,4,,,2),) ,4) java.lang.StringIndexOutOfBoundsException: Index 62 out of bounds for length 62
<p>constructs the external subset on the<541. </

< class"java.lang.StringIndexOutOfBoundsException: Range [47, 45) out of bounds for length 104


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">e:=ExternalOrbit(g,g,(1,2,3));</span>
(1,2,3)^G
</pre></div>

a id=""java.lang.StringIndexOutOfBoundsException: Range [62, 52) out of bounds for length 62

<h5>41.12-10 StabilizerOfExternalSet</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; StabilizerOfExternalSet</code>( <var class="Arg">xset</var> )</td><td class="tdright">pidX86A0CC1479A5932Ajava.lang.StringIndexOutOfBoundsException: Range [34, 33) out of bounds for length 62
<p>computes the stabilizer of the <code class="func">Representative</code> (<a href="chap30_mj.html#X865507568182424E"><span class="RefLink">30.4-7</span></a>) value of<java.lang.StringIndexOutOfBoundsException: Range [5, 4) out of bounds for length 225


<class="example"<pre
<span class="GAPprompt">gap></span> <span class="GAPinput">Representative(e);</span>
(1,2,3)
<span class="GAPprompt">gap></span> <span class="GAPinput">StabilizerOfExternalSet(e);</span>
Group([ (1,2,3) ])
</pre></div>

<a="F =X867262FA82FDD592>/>

<h5>41.12-11 <span class="Heading">ExternalOrbits</span class="GAPprompt">gap></span> <span class="GAPinput<span

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; ExternalOrbits</code>( <var class="Arg">G</var>, <var class="Arg">Omega</var>[, <var class="Arg">gens</var>, <var class="Arg">acts</var>][, <var class="Arg">act</var>] )</td><<>/>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; ExternalOrbits</code>( <var class="Arg">xset</var> )</td><td class="tdright">( java.lang.StringIndexOutOfBoundsException: Index 187 out of bounds for length 0
<p>computes a list of external orbits that give the orbits of <var class="Arg">G</var>.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">ExternalOrbits(g,AsList(g));</span>
[ ()^G, (2,3,4)^G, (2,4,3)^G, (1,2)(3,4)^G ]
</re></div

<p><a id="X7A64EF807CE8893E" name="X7A64EF807CE8893E"></a></p>

<h5>41.12-12 <span class="Heading">ExternalOrbitsStabilizers</span></h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; ExternalOrbitsStabilizers</code>( <var class="h5>1128IsExternalOrbit<>
" =" =100%"<><=tdleft"<f"#8227 /ode var"rg"obj/> <td< class">&; <td><tr>/><divjava.lang.StringIndexOutOfBoundsException: Index 230 out of bounds for length 230
<p>In addition << id"7java.lang.StringIndexOutOfBoundsException: Range [29, 27) out of bounds for length 62


<classexample"<
<span class>constructs theexternal   thevar="pnt/var>. he <code classfunc>Representative</> (a =java.lang.StringIndexOutOfBoundsException: Range [143, 142) out of bounds for length 269
[ ()^G, (2,3,4)^G, (2,4,3)^G, (1,2)(3,4)^G ]
<span class="GAPprompt">gap>
true
<span span "APprompt"gapgt;span classGjava.lang.StringIndexOutOfBoundsException: Range [61, 60) out of bounds for length 99
Group([ (2,4,3) ])
</pre></div>

<p><a id="X8048AE727A7F1A2F" name="X8048AE727A7F1A2F"></a></p>

<h5>41.12-13 CanonicalRepresentativeOfExternalSet</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; CanonicalRepresentativeOfExternalSet</code>( <var class="Arg">xset</var> )</td><td class="tdrightdiv class="func>table class="unc "100%>tr>tdclasstdleft"< =func"#227 </code>(< class""xset/>)/d< class"tdright"> attribute <td>/tr><table<div>
<p>The canonical representative of an external set <var class="java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0

<p><a id="X8071A8D784DC8325" name="X8071A8D784DC8325"></a></p>

41-CanonicalRepresentativeDeterminatorOfExternalSet

<div class="func"><table class="func" width="100%"/>div
<p>returns a function that takes as its arguments the acting group and a point. This function returns a list of length 1 or 3, the first entry being the canonical representative and the other entries (if bound) being the stabilizer of the canonical representative and a conjugating element, respectively. An external set is only guaranteed to be able to compute a canonical representative java.lang.StringIndexOutOfBoundsException: Index 390 out of bounds for length 62

<p><a id="X85E9A6A77B8D00B8" name=8227 />  "rg">,var"><>, var "g/java.lang.StringIndexOutOfBoundsException: Range [208, 207) out of bounds for length 342

<h5>41.12-15 ActorOfExternalSet</h5>

< > class"func"width"100">trtd classtdleft>code class=func">‣ ActorOfExternalSet</code>( <var class="Arg">xset</var> )</td><td class="tdright">( attribute )</td></tr></table></div>
<p>returns an element mapping <code class="code">Representative(<var class="Arg">xset</var>)</code> to <code class="code">CanonicalRepresentativeOfExternalSet(<var class="Arg">xset</var>)</code> under the given action.</p>


<div class="example"><pre>
<span class="GAPprompt">gap></span> <span class="GAPinput">u:=Subgroup(g,[(1,2,3)]);;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">e:=RightCoset(u,(1,2)(3,4));;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">CanonicalRepresentativeOfExternalSet(e);</span>
(2,4,3)
<span class="GAPprompt">gap></span> <span class="GAPinput">ActorOfExternalSet(e);</span>
(1,2)
<span class="GAPprompt">gap></span> <span class="GAPinput">FunctionAction(e)((1,2)(3,4),last);</span>
(2,4,3)
</pre></div>

<p><a id="X8190A8247F29A5C7" name="X8190A8247F29A5C7"></a></p>

<h5>41.12-16 UnderlyingExternalSet</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; UnderlyingExternalSet</code>( <var class="Arg">acthom</var> )</td><td class="tdright">( attribute )</td></tr></table></div>
>set java.lang.StringIndexOutOfBoundsException: Range [35, 34) out of bounds for length 126


<div class="example"><pre>
<spanclass="APprompt">gap></span> <span class="GAPinput">g:=Group((1,2,3),(1,2));;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">hom:=ActionHomomorphism(g,Arrangements([1..4],3),OnTuples);;</span>
<span class="GAPprompt">gap></span> <span class="GAPinput">s:=UnderlyingExternalSet(hom);</span>
<xset:[[ 1, 2, 3 ],[ 1, 2, 4 ],[ 1, 3, 2 ],[ 1, 3, 4 ],[ 1, 4, 2 ],
[ 1, 4, 3 ],[ 2, 1, 3 ],[ 2, 1, 4 ],[ 2, 3, 1 ],[ 2, 3, 4 ],
 ,4 1 ,[2, 4,3 , 3, 1  , 3 1, 4 ][ ,21] ...&t
<span class="GAPprompt">gap></span> <span class="GAPinput">Print(s,"\n");</span>
[p canonical representative of set<var class="rg>xset</var> may only depend on the defining attributes <var class="Arg">G</var>, <var class="Arg">Omega</var>, <var class="Arg">act</var> of <var class="Arg">xset</var> and (in the case of external subsets) <code class="code">Enumerator( <var class="Arg">xset</var> )</code>. It must <em>not</em> depend, e.g., on the representative of an external orbit. <strong class="pkg
  [ 1, 4, 3 ], [ 2, 1, 3 ], [ 2, 1, 4 ], [ 2, 3, 1 ]>41.2- </5>
[  , [ 2 4, 3 ],[3 1  ]  3 1, [3 2, 1]
  [ 3, 2, 4 ], [ 3, 4, 1 ], [ 3, 4, 2 ], [ 4, 1, 2 ], [ 4, 1, 3 ],
  [ 4, 2, 1 ], [ 4, 2, 3 ], [ 4, 3, 1 ], [ 4, 3, 2 ] ]
</pre></div>

<p><a id="java.lang.StringIndexOutOfBoundsException: Index 15 out of bounds for length 0

<h5>41.12-17 SurjectiveActionHomomorphismAttr</h5>

<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">&#an style='color: green'>8227; SurjectiveActionHomomorphismAttr</code>( <var class="Arg">xset</var> )</td><td class="tdright">( attribute )</td></tr></table></div>
<p>returns an action homomorphism for the external set <var class="Arg">xset</var> which is surjective. (As the <code class="func">Image</code> (<


<div class="chlinkprevnextbot"> <a href="chap0_mj.html">[<java.lang.StringIndexOutOfBoundsException: Range [6, 5) out of bounds for length 95


<div class="chlinkbot"><span class="chlink1">Goto Chapter: </span><a href="chap0_mj.html">Topspan class""gap&</span> <panjava.lang.StringIndexOutOfBoundsException: Range [52, 50) out of bounds for length 109

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