Quellcode-Bibliothek o8p2s3_o8p5s3.xml
Sprache: XML
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<& ComputationsM>_+5._</M> M./><>
Date: October 08th, 2006
<P/>
This chapter shows how to construct a representation of the automorphic
extension <M>G</M> of the simple group <M>S = O_8^+(5)</M>
by a symmetric group on three points,
together with an embedding of
!-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%-java.lang.StringIndexOutOfBoundsException: Index 77 out of bounds for length 77
P>
As an application, it is shown that the permutation representation of <M>G</M>
n cosetsof <H/ a baseoflengthjava.lang.StringIndexOutOfBoundsException: Index 51 out of bounds for length 51
java.lang.StringIndexOutOfBoundsException: Range [9, 4) out of bounds for length 48
<-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ->
< Label":verview_o8p2s3java.lang.StringIndexOutOfBoundsException: Index 38 out of bounds for length 38
<eading>verview/eading
Let MO8+)/ such that the normalizer <M>H</M>, say,
<M>O_8^+(5) \cong </of <M><Min<><M>is automorphic ofMM/>
that is,the simplegroupthat occursas composition
of the general orthogonalMO8+2<M>java.lang.StringIndexOutOfBoundsException: Range [17, 18) out of bounds for length 17
matrices over the field with five elements.
<P/>
The outer automorphism group of <M>S</M> is Analogously, let <M>M.2 = H \cap S.2</M> and <M>M.3 = H \cap S.3</M>.
on four pointsjava.lang.StringIndexOutOfBoundsException: Index 15 out of bounds for length 15
Let<G/>beautomorphicextension of <M>S</M> by the symmetric group
on three points.
By <Cite Key="Kle87"/>,
the group <M>S</M> contains a maximal subgroup <M>M</M> of theand the reduction of its rational <M>8</M>-dimensional representation modulo
<<M>5/M> embeds into the general orthogonal group GO<M>{}^+(8,5)</M>,
f<><M <><M anautomorphicextension of <></>by
a Thenthe of GO<>}+8)/M> isomorphicimage <><M
(GO>{^(5<M>on <><M>spaces in the
<>^+(2)/>)
<P/>
Let <M>S.2</M> and <M>S.3</M> denote intermediate java.lang.StringIndexOutOfBoundsException: Index 54 out of bounds for length 29
<M>S</M> and <M>G</M>,
java.lang.StringIndexOutOfBoundsException: Range [7, 2) out of bounds for length 70
Analogously, let <M>M.2 = H \cap S.2</M> java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<P/>
In Section <Ref Subsect="sect:sect2"/>,
we use the followingwe take outer M\</>of MM<> orderthree,
<S2/.
By;Cjava.lang.StringIndexOutOfBoundsException: Range [14, 13) out of bounds for length 42
java.lang.StringIndexOutOfBoundsException: Range [20, 3) out of bounds for length 75
the of its rational<M><M- representationmodulo
<M>5</M> embeds into the general orthogonal group GO<M>{}^+(yieldspermutationrepresentations MS.</>and its subgroup
which has the structure <M>2.O_8^+(5).2^2</
java.lang.StringIndexOutOfBoundsException: Range [35, 4) out of bounds for length 77
in GO<M>{}^+(8,5)</Mw put theabove together,
natural module of <>^(8,5)<>yield<>.2<M a subgroupof
(a supergrouppoints.
where both groups are represented as permutation groups on <M>N = 19\,656</M>
java.lang.StringIndexOutOfBoundsException: Index 17 out of bounds for length 7
<P/>
In Section <Ref Sect="sect:sect3"/>,
first we use &has a base of length two;
Then we take an outer automorphism <M>\alpha<this question arose &bsp< Key"">java.lang.StringIndexOutOfBoundsException: Index 48 out of bounds for length 48
and extend f characterM(1HG)_/>
,we the images of generating of <</>and <M>M</M>
<>alpha/>and<\^<M>
This yields permutation see Section <Ref Subsect="sect:appendix_data"/>).
<M>M.3<java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<P/>
In Section <Ref Sect="sect:sect4"S Label=sect:java.lang.StringIndexOutOfBoundsException: Range [28, 26) out of bounds for length 28
we the above informationtogether
in order to construct permutation representations of <M>G</M> and
on M3N<M>points.
<P/>
As an application, it is shown in Section Heading> MatrixRepresentation the ofTypeE8/>/eading
thatinn;CiteKey="CN85 =p.85,Section">
has a base of we can generate the Weyl group <M>W</M> of type <M>E_8</M> as a group of
this questionarose in; Key=B">java.lang.StringIndexOutOfBoundsException: Index 48 out of bounds for length 48
</
In two appendices, it plus the vectors obtained from these by permuting the coordinates,
from the permutation character<(_^G)_<M>
(see Section&
java.lang.StringIndexOutOfBoundsException: Range [10, 3) out of bounds for length 72
( \(\m 1/,\m /,p 1/,\m 1/2,
<!-- %%%%%%%%%%%%%%%%%%%%%%%%
< Label="subsect:epres_W_E8>
<java.lang.StringIndexOutOfBoundsException: Range [9, 8) out of bounds for length 79
Following<M>\pm v</\ <>java.lang.StringIndexOutOfBoundsException: Index 14 out of bounds for length 14
in="CCN85"Where=p85, Weyl/,
we can generate the Weyl group <M>W</M> of type <M>E_8</M> as a group gap>for iin( [ 1. ,2)java.lang.StringIndexOutOfBoundsException: Index 46 out of bounds for length 46
rational <M>8 \times (rootvectors )
vectors
<Display Mode="M" {}=[11]
\> od;
</Display>
plus the vectors obtained from these by java.lang.StringIndexOutOfBoundsException: Index 46 out of bounds for length 25
plus those those vectors of the form
<isplay =M"
\left( \pm 1/>we8: (List ,ReflectionMat;
\pm 1/2, \pm 1/2, \pm 1/2, \pm<atrix >
<Displayjava.lang.StringIndexOutOfBoundsException: Index 10 out of bounds for length 10
that have an even number of negative signs.
(Clearly it is sufficient to consider only one vector form <Heading>Embedding the Weyl group of Type <M>E_8</M> into GO^8,)>
<M>\pm v</M>.)
<P/>
<>!CDATAjava.lang.StringIndexOutOfBoundsException: Index 18 out of bounds for length 18
gap> gap> ForAll( GeneratorsOfGroup( we8 ), x -> x * TransposedMat(x) = I );
gap>for in java.lang.StringIndexOutOfBoundsException: Range [27, 26) out of bounds for length 46
>java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
> v{i}:= [ 1, 1 ];
> Add( rootvectors, of orthogonal matrices w.& matrices w. r. t. the identity matrix.
> v:= 0 * [ 1 .. 8 ];
> v<Ref Func="BookName="/
> (rootvectors )
>>
gap (rootvectors,
> 1/2 * Filtered( Tuples( [ -1, 1 ], 8 ),
> x -> x[1] = 1 and > Display( InvariantBilinearForm( largegroup
gap> we8:..2 . .
<matrix group with 120....2..java.lang.StringIndexOutOfBoundsException: Index 16 out of bounds for length 16
]<Examplejava.lang.StringIndexOutOfBoundsException: Index 13 out of bounds for length 13
</we need a <M>2 \times 2</M> matrix <M>T</M> over the field with five elements
<!-- P>
<Subsection Label="subsect:embedding_W_E8">
<java.lang.StringIndexOutOfBoundsException: Index 5 out of bounds for length 0
The elements in the group constructed above respect the symmetric bilinear
form that is given by the identity matrixgap ( ))java.lang.StringIndexOutOfBoundsException: Index 43 out of bounds for length 43
<P/>
<Example><![CDATA[
gap> I:= IdentityMat( 8 );;
ForAll ( java.lang.StringIndexOutOfBoundsException: Range [37, 35) out of bounds for length 71
true
]java.lang.StringIndexOutOfBoundsException: Index 4 out of bounds for length 4
<P/>
So the reduction of the java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0
orthogonal .nbsp;.nbsptnbsp;theidentitymatrixjava.lang.StringIndexOutOfBoundsException: Index 67 out of bounds for length 67
The group GO<M>{}^+(8,5)</M>of PGOM{^(,5)M,
R=G"BookName"ef"
a which is by actionof GO<M>^(8,)/>on the smallest orbit
In order to conjugate <M>W^{\ast}<gap> N: Length [ ;
we need a <M>2 \times19656
java.lang.StringIndexOutOfBoundsException: Range [28, 4) out of bounds for length 38
is half of java.lang.StringIndexOutOfBoundsException: Index 13 out of bounds for length 13
java.lang.StringIndexOutOfBoundsException: Index 6 out of bounds for length 4
< of its <M>M<M java.lang.StringIndexOutOfBoundsException: Range [50, 49) out of bounds for length 50
gap> T:= [ [ 1, 2 ], [ 4, 2 ] ] * One( GF(5) );;
gap> Display( 2 * T * TransposedMat( T ) );
. 1 1 .
gap> I:= IdentityMat( 8, GF(5) );;
gap> I{ [ 1, 2 ] }{ [ 1, 2 ] }:= T;;
gap> conj:= List( GeneratorsOfGroup( we8 ), x -> I * x * I^-1 );;
gap> IsSubset( largegroup, conj );
true
]]></Example>
</Subsection>
<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="subsect:120pt">
<Heading>Compatible Generators of <M>M</M>, <M>M.2</M>, <M>S</M>, and <M>S.2</M></Heading>
For the next computations,
we switch from the natural matrix representation of GO<M>{}^+(8,5)</M>
to a permutation representation of PGO<M>{}^+(8,5)</M>,
of degree <M>N = 19\,656</M>,
which is given by the action of GO<M>{}^+(8,5)</M> on the smallest orbit
of <M>1</M>-spaces in its natural module.
In the same way,
permutation representations of the subgroup <M>M.2 \cong </M>SO<M>{}^+(8,2)</M>
and of its derived subgroup <M>M</M> are obtained.
But first we compute a smaller generating set of the simple group <M>M</M>,
using a permutation using a permutation representation on <M>120</M> points.
<P/>
<Example><![CDATA[
gap> orbwe8:= SortedList( Orbit( we8, rootvectors[1], OnLines ) );;
gap> Length( orbwe8 ); 120
gap> java.lang.StringIndexOutOfBoundsException: Index 12 out of bounds for length 4
gap> m2_120:= Imagegap (orbwe8 ;
p> m_120:= DerivedSubgroup(m2_120 );;
Length ); 2
gap> gens_m:= List( sml, x -> PreImagesRepresentative( we8_to_m2, x ) );;
]><Example
<P/>
Now we compute the actions of <M>Mg>sml:=SmallGeneratingSetjava.lang.StringIndexOutOfBoundsException: Range [37, 36) out of bounds for length 56
on the above orbitjava.lang.StringIndexOutOfBoundsException: Range [0, 19) out of bounds for length 13
generating<>.<M> choose <bN iM.2\java.lang.StringIndexOutOfBoundsException: Range [73, 72) out of bounds for length 79
which is obtained action matrix <M>b \in 2.M.2 \setminus 2.M</M>.
P/
<Example><![CDATA[
gap> gens_m_N
>x- ( x*I^1 ,OnLines));
java.lang.StringIndexOutOfBoundsException: Index 2 out of bounds for length 0
x-(I* ^-1,orbNO );java.lang.StringIndexOutOfBoundsException: Index 58 out of bounds for length 58
>DeterminantMatb ;
Z(5)^2
gap> b_N:= Permutation( b, orbN, OnLines );;
gap> m2_Ngap DeterminantMat ;
]]>/>
<P/>
(Note that <M>M.2</M> is not contained in PSO<M>{}^+(8,5)</M>,
since the java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0
<P/>
java.lang.StringIndexOutOfBoundsException: Range [18, 3) out of bounds for length 66
and <M>S.2</M> isjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<P/>
<Example><![CDATA[
gap> s_N:= and <M>S.2</M> is generated by <M>S</M> together with <M>b_N</M>.
gap> java.lang.StringIndexOutOfBoundsException: Index 7 out of bounds for length 0
]>/Example
</Subsection>
</Section>
<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<java.lang.StringIndexOutOfBoundsException: Index 3 out of bounds for length 0
Hjava.lang.StringIndexOutOfBoundsException: Range [9, 8) out of bounds for length 76
<!-- %%%%%%%%%%< Label"sects">
< Label=:.M">
<Heading>The Action of <M>M.3</M> on <M>M</M></Heading>
et M\<M> an automorphismof <M>M</M>, of order three.
Then a representation of the semidirect product <M>M.3</M> of <M>M</M> by
<M>\langle \alpha \rangle</M> can be constructed as follows.
<P/>
If <M>M</M> is given by a matrix representation then we map <>g \inM<Mjava.lang.StringIndexOutOfBoundsException: Index 74 out of bounds for length 74
the matrix
<Alt Only
[
\[\eginarray}{cc}
g & & \\
& <M\langle alpha\<Mcbe constructed followsjava.lang.StringIndexOutOfBoundsException: Index 60 out of bounds for length 60
;&;g{\lpha^}
\end{array} \right] ,
\]
</Alt>
<java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0
<erb>
⌈ g ⌉
| g^α |
& amp ^\^2)
<Verb>
</Alt>
<Alt Only="HTML"><![CDATA[
<div class="pcenter">
t =Text">
<tr>
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< ⌊g^α2)⌋
<td
/>
<tr>
td class"dright"< S">nbsp<span>/>
<td class="tdright"><span class="SimpleMath">g^α</span></<class="pcenter>
<td class<r>
<<td class=tdright>span=SimpleMath">g</span></>
t>
=tdright>span class"SimpleMath>nbsp<s>/>
<td java.lang.StringIndexOutOfBoundsException: Index 14 out of bounds for length 9
<td class="tdright"><span <td class="tdright"><span class"g^α/>/d>
</tr>
</table>
</div>
]]></Alt>
and we represent < =tdright"<class=SimpleMath"&;/><t>
<Alt Only="LaTeX">
\[
\left[ <td class"tdright"s classS"g^^)<span>tjava.lang.StringIndexOutOfBoundsException: Index 70 out of bounds for length 70
amp amp;I \
end{array}right] ,
& I &
\end{array} \right]>
\]
</Alt>
<Alt Only="Text">
<Verb>
java.lang.StringIndexOutOfBoundsException: Range [28, 26) out of bounds for length 35
| I |
java.lang.StringIndexOutOfBoundsException: Index 7 out of bounds for length 7
</Verb>
<Alt>
<Alt Only="td ""<class""&;/><tjava.lang.StringIndexOutOfBoundsException: Range [69, 70) out of bounds for length 69
<div class="<td class="td">span="I</span<tdjava.lang.StringIndexOutOfBoundsException: Index 64 out of bounds for length 64
<">
<tr>
td "dright"< =SimpleMath>;/>/>
<td class="tdright"><span class="SimpleMath"> </span></td>
java.lang.StringIndexOutOfBoundsException: Range [24, 6) out of bounds for length 64
</tr>
<tr>
< class=t">span class=S></pan<t>
<td class= t ""span class""I</>/>
<<tdclass="tdright"< ="nbsp;/span<tdjava.lang.StringIndexOutOfBoundsException: Index 69 out of bounds for length 69
</tr>
<tr>
<td class=" <></>is the identity MM<M>
<td class="java.lang.StringIndexOutOfBoundsException: Index 23 out of bounds for length 4
<class=tdright"<="&bsp;/pan>/d>
</tr>
</table>
<div>
]u M\<Mand M\^2</.
where <M>I</<P/
<P/>
We need the action of <M>\alpha</M> on <M>M</M>.
More ,we need generatorsof<>/>
under <M>\alpha</M> and <M>\alpha^2for that use degreeM>20</>permutation
<P/>
The group <M>M</java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
its automorphism ,is isomorphicwith MO+82)S_3>;
for that, we use the degree <M>120</M> permutation representation
constructed in Section 
<P/>
<Example><![CDATA[
gap> aut_m</
]]
<Pg>:= NiceMonomorphism )
We outerautomorphism<alpha/> orderthree.
<P/>
<Example>repeatx: Random()
java.lang.StringIndexOutOfBoundsException: Range [10, 3) out of bounds for length 45
>:=((nice_aut_m ;java.lang.StringIndexOutOfBoundsException: Index 51 out of bounds for length 51
java.lang.StringIndexOutOfBoundsException: Range [6, 3) out of bounds for length 36
gap> repeat x:Random( der );
> ord:= Order( x );
> until ord mod 3 = 0 and ord mod 9 <> 0 and not ]<Example
gap>x: ^ /3 ;java.lang.StringIndexOutOfBoundsException: Index 24 out of bounds for length 24
gap alpha_120=PreImagesRepresentative,x ;java.lang.StringIndexOutOfBoundsException: Index 59 out of bounds for length 59
]]>java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<Pgap : ( -Image(alpha_120, ));
Next theimagesof thegenerators Csml<C M\</>
and <M>\alpha^2</M>,
and the corresponding elements in the action of <M>M</M> on <M> PreImagesRepresentative ,);
<P/>
<Example><![CDATA[
gap> > gens_m_N_alpha( gens_m_alpha,
gap> x- ( * *I^-,orbN ;
gap : (,
> - PreImagesRepresentative(we8_to_m2 );;
gap> gens_m_alpha_2java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
> -( , x ));
gap> gens_m_N_alpha:= List( gens_m_alphaa java.lang.StringIndexOutOfBoundsException: Range [58, 57) out of bounds for length 76
>
gap> gens_m_N_alpha_2:= java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
> x -> Permutation( smallgroup is />
]]></Example>
<P/>
Finally, we use the construction descibed in the beginning of and using <>^alpha</M> mustin<C_SC_M()\)/,
and obtain a permutation representation of <Mwe check ofthis subgroupcan be desired
points.
<!-- gap> shift:= Product( List( [ 1 .. N ], i -> (i,i+N,i+2N) ) );;
# exceeds the memory! -->
</Subsection>
<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -->
<Subsection Label="subsect:M.3andS.3">
<Heading>The Action of <M>S.3</M> on <M>S</M></Heading>
Our approach is to extend the automorphism <M>\alpha</M> of <M>M</M> to
<M>S</M>;
we can do this because in the full automorphism group of <M>S</M>,
<E>any</E> <M>O^+_8(2)</M> type subgroup extends
to a group of the type <M>O^+_8(2).3</M>, and this extension lies in a
subgroup of the type <M>O^+_8(5).3</M> (see<M> has a root <M>s</M> of order
<P/>
The group <M>M</M> is maximal in <M>S</M>,
so <M>S</M> is generated by <M>M</and <M>C_S(x)</M> has order <M>189<
<M>s \in S element <>y \n C_S(M)\)/>has M><M>java.lang.StringIndexOutOfBoundsException: Index 75 out of bounds for length 75
Having fixed such an element equalto theof of My/>and imagesof these
java.lang.StringIndexOutOfBoundsException: Range [10, 2) out of bounds for length 65
2/.
<>
For that, we first choose <M>x \in M</M> such that <M>C_S(xjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
> gens_m_N,gens_m_N_alpha;
Then we choose <M>s \in C_S(x) \setminus M</M>,
java.lang.StringIndexOutOfBoundsException: Range [20, 3) out of bounds for length 69
we then check returnOrder ) (cand) and
image.
<P/>
Each element <M>x</M> java.lang.StringIndexOutOfBoundsException: Index 28 out of bounds for length 28
M63/>in<M><M>
and <M> until( )=63;
For such <>x/>
good:= Filtered( Elements( Centralizer( s_N, c_m_alpha ) ),
satisfies the necessary x - ( gens_m_N,
that the orders of >gens_m_N_alpha,s,x ))
are equal to the orders > until Length( good )
generators under <M>\gap> c_m_alpha_2:= Images( alpha, c_m_alpha );;
In other words, we have <M>gap> = Filtered Elements ( c_m_alpha_2))java.lang.StringIndexOutOfBoundsException: Index 66 out of bounds for length 66
<P/>
<Example><![CDATA[
gap> : [];
>]]>/Example
gap> CheapTestForHomomorphism:= java.lang.StringIndexOutOfBoundsException: Range [1, 40) out of bounds for length 4
> returnthis meansthat of<>3/ on M3<>
> ForAll( [ 1 .. Length( gens ) ],
> [i] * x )=Ordergenimages[] ))java.lang.StringIndexOutOfBoundsException: Index 72 out of bounds for length 72
> end;;
gap> \left \egin{rray}{cc}
t
> & \ amp;\java.lang.StringIndexOutOfBoundsException: Index 35 out of bounds for length 35
> until Order( \end{array}],
> java.lang.StringIndexOutOfBoundsException: Index 9 out of bounds for length 6
> repeat
> s:= Random( c_s );java.lang.StringIndexOutOfBoundsException: Range [70, 24) out of bounds for length 70
> until Order
> : ,Centralizerm_N, ;
> good:= Filtered( Elements( Centralizer( s_N, c_m_alpha ) ),
> x java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
> gens_m_N_alpha, s, x ) );
> until Length( good ) =]</>
gap> s_alpha:= good[1]P>
gapjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
gap> good:= Filtered( Elements( which yields generators for <M>S</M> that are compatible with those of
> <M>M</M>
> s_alpha, x )<>
gap> s_alpha_2
]>/>
<P/>
Using notation previoussection,
thisjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
be extendedMS.<>by permutation corresponding
to the block diagonal java.lang.StringIndexOutOfBoundsException: Index 24 out of bounds for length 0
<lt Only="aTeX>
\[
l begina}ccc}
s & & \\
&<> Generators of <M>H</M> and <M>G</M></Heading>
& &After having compatiblerepresentations MM2/>
\end{array} \right] ,
\]
</Alt>
<Alt Only="Text">
<Verb>
⌈ s ⌉
sα|
(^)⌋java.lang.StringIndexOutOfBoundsException: Index 44 out of bounds for length 44
</Verb>
</Alt>
<Alt Only="HTML"><![java.lang.StringIndexOutOfBoundsException: Range [4, 1) out of bounds for length 43
<ivclass=p">
Theactiononfirst M></M thatofthe
<tr>
java.lang.StringIndexOutOfBoundsException: Range [33, 6) out of bounds for length 64
<td class=" Sectionn;RefSubsect="ubsect:120pt".
<td class="tdright"><span class="SimpleMath"> </span></td>
</List
java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<td class=Usingthe the ,
td class="tdright"><span ^s><td>
<td class="tdright"><span class="SimpleMath"> </span></td>
</tr>
<tr><ltOnly"aTeX>
<td class="tdright"><span class="SimpleMath"> </span></td>
<td class="left[ \begin{array}{ccc}
<td class="tdright"><spanb && \
</tr>
</table>
</div>
]]></Alt>
as\end{rray right ,
<P/>
<Example><![<lt Only=""
gap<Verb>
gap⌈
]
<>
(And of java.lang.StringIndexOutOfBoundsException: Index 11 out of bounds for length 8
hichyieldsfor <><M> that are with thoseof
<M>M</M>.)
<P/>
<Example><![CDATA[
gap> s_3N:= ClosureGroup( m_3N, java.lang.StringIndexOutOfBoundsException: Index 35 out of bounds for length 9
]]></Example>
<Subsection>
</Section>
<!-- (n <>N<M ),
<Section Label="sect:sect4">
<Heading>Constructing Compatible Generators of <M>H</M> and <<>g/M> describes the inner automorphism <M>\gamma</M> of <M>M</M>
e of <M2M
<M>G.2</M> on <and <M>d</M> describes <M>\gamma \gamma^\alpha</M>.
(see Section <Ref SubsectP/
and
( Section&bsp;<Subsect="ubsect:.andS3">,
the last construction step is to find a permutation on <M>3 N</M> points
with the following properties:
<List>
<tem>
The induced automorphism <M>\beta</M> of <M>M</M> extends to <M>M.3</M>
ism <>alpha</>of MMM inverted
modulo inner automorphisms of <M>M</Section <Ref Subsect="subsect:120pt"/>.
</Item>
<Item>
The action on the first <
Example<C[
Section <Ref Subsectgap>b_120=( we8.1 ,OnLines ;java.lang.StringIndexOutOfBoundsException: Index 52 out of bounds for length 52
</Item>
</List>
<P/>
Using := ( I PreImagesRepresentative _ java.lang.StringIndexOutOfBoundsException: Index 71 out of bounds for length 71
we represent <M>\beta</M> by a blockgap> :=( I *PreImagesRepresentative,
<Alt Only="LaTeX">
\[
\left[ \begin{array}{cccgap : (Concatenation
> ListPerm )
amp;&mpbd \\
& b g &
\end{ (b_N*g_N )+ ) );
\
java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<Alt Only="Text">
<Verb>
java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
| Example><![DATA
b g ⌋,
</Verb>
<gap>g= (s3_3N,inv;
<Alt Only="HTML"><![CDATA[
<iv class="="center">
<table class="GAPDocTable">
<tr>
<td/ection>
<td class="tdright"><span class="java.lang.StringIndexOutOfBoundsException: Index 47 out of bounds for length 0
<td class="tdright"><span class =secta"java.lang.StringIndexOutOfBoundsException: Index 27 out of bounds for length 27
</tr>
<java.lang.StringIndexOutOfBoundsException: Index 7 out of bounds for length 0
<td class="tdright"><span class="SimpleMath"> </span></<M>/<M.
td ">span class=SimpleMath"&bsp/></>
s areelements <Ms\n </>with property
</<|\cap^s| 1<M>
t java.lang.StringIndexOutOfBoundsException: Range [16, 15) out of bounds for length 69
<td class="tdright"Of course this implies that also in the permutation representations of
<td class="tdright"><span class="SimpleMath"> </span></td>
<tr>
</table>
</div>
]]></Alt>
where <M>b</M> describes the action of <M>\beta</M> on <M>M</M>
(on <M>N</M> pointsjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<M>g</M> describes the innergap
java.lang.StringIndexOutOfBoundsException: Range [6, 4) out of bounds for length 77
and <M>d</M> describes <M>\gamma =Intersection ^ )
<P/]>/>
SoP/
<M>\java.lang.StringIndexOutOfBoundsException: Index 6 out of bounds for length 0
We do this in the representation of <M>M</M> on <M>120</M> points,
nd carry over the result the on <M><> points,
via the rational matrix representation;
this approach had been used already in
Section<>
<P/>(omputingone such takes sixminutes
<Example><![CDATA[
gap:=Permutation . orbwe8 ;java.lang.StringIndexOutOfBoundsException: Index 52 out of bounds for length 52
gap> g_120:= RepresentativeAction( m_120java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
List sml_alpha_2 >x^_)java.lang.StringIndexOutOfBoundsException: Index 51 out of bounds for length 51 20) ), OnTuples)
gap> g_120_alpha:= Heading>Appendix: The PermutationThePermutation <(_^_M>H>
gap> g_N:= Permutation( I * PreImagesRepresentative( we8_to_m2, g_120 )
> </
gap> g_N_alpha:Asalternative the of<>H c H^<M>suitable
> > \S/>, we tryto fromthe
gap>java.lang.StringIndexOutOfBoundsException: Range [9, 8) out of bounds for length 35
> java.lang.StringIndexOutOfBoundsException: Range [32, 31) out of bounds for length 39
>ListPerm )+2*,
> ListPerm( b_N * g_N * g_N_alpha ) + N ) );;
]]></Example>
<!-- %%%%%%%%%%%%%%%%%%%%implicitly,
<Section Label="sect:appl">
<Headingjava.lang.StringIndexOutOfBoundsException: Index 8 out of bounds for length 0
toshow thatM</>has java.lang.StringIndexOutOfBoundsException: Range [42, 41) out of bounds for length 68
<M>G/H</M>bit to usea degree <405/>representation
in<><M>of thecoset< g<M> <M> cap Hg/java.lang.StringIndexOutOfBoundsException: Index 72 out of bounds for length 72
o that there <M>\n />with property
<M>|H \cap H^s| = 1</M>.
<P/>
(Of course this implies that also in the permutation <Ref Func="SmallerDegreePermutationRepresentation" BookName" BookName="ref"/>.)
the subgroups <M>S</M>, <M>S.2</M>, and
cosets of the intersection java.lang.StringIndexOutOfBoundsException: Index 29 out of bounds for length 0
the point stabilizers have regular orbits.)
</
<Example><![CDATA[
gap> repeat
>
> inter:= Intersection( h, h^conj );
> java.lang.StringIndexOutOfBoundsException: Range [11, 10) out of bounds for length 29
]<Example>
<P/>
Eventually &GAP(Orbit(h, oneblock, OnSets ) );;
so there are elements <M>s</M> gap> ccl:= ConjugacyClasses( Image( acthom ) );;
<P/>
(Computing one such > ( ));java.lang.StringIndexOutOfBoundsException: Index 57 out of bounds for length 57
on a 2.5 GHz Pentium
so may ave be bit patient.)
</Section>
<!-- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%in <><M.
<Section Label="sect:appendix_permchar>
<Heading>Appendix: The Permutation Character <M>(1_H^G)_H</M></java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0
P>
As an alternative to the computation of <M>|H \cap H^s|</M> for suitable
<Mg :[];
permutation character <M>(1_H^G)_H</M>.
Unfortunately, there seems to be no easy way to> in[1 . ( reps do
its<>/<M>
(cf. Section <Ref Sect="sect:appl"/>)
> :Size( Centralizer , reps[))
</
,it is not to orbits
of <M>M</M>,( gg,fusrepsj],[])
For > []=j;
by computing class representatives of <M>H</M>,
their centralizerjava.lang.StringIndexOutOfBoundsException: Range [25, 24) out of bounds for length 37
andthe class fusion <H<M>classesin<><M.
<P/>
We want to compute the if found then
ofM<
this could be done using the (fusion, java.lang.StringIndexOutOfBoundsException: Range [38, 37) out of bounds for length 42
implicitly constructed>od;
<!-- (Each java.lang.StringIndexOutOfBoundsException: Range [0, 16) out of bounds for length 0
<M>Next we compute the permutation character values,
butis easier use degree <M405/>representation
that is obtained from the degree <M>58\,968</java.lang.StringIndexOutOfBoundsException: Range [0, 46) out of bounds for length 18
by the action of <M>H</M> java.lang.StringIndexOutOfBoundsException: Range [0, 28) out of bounds for length 10
a &AP;function
<that are<>G>conjugate to <></>
<P/</java.lang.StringIndexOutOfBoundsException: Index 4 out of bounds for length 4
<Example><![CDATA[
gap> orbs:= Orbits( h, MovedPoints( h ) );;
gap> List( orbs, Length );
[ 22680, 36288 ]
gap>orb:=orbs[1];
gap> bl:= Blocks( h, orb );; Length( bl[1] ); 2
gap> actbl:= Action( h, bl, OnSets );;
gap> bll:=Blocks(actbl( actbl));Length ) 405
gap> oneblock:= Union( bl{ bll[1] } );;
java.lang.StringIndexOutOfBoundsException: Range [7, 3) out of bounds for length 55
gap> acthom:= ActionHomomorphism( h, orb, java.lang.StringIndexOutOfBoundsException: Index 44 out of bounds for length 0
gap> ccl:= ConjugacyClassesIn permutation characterw..&;he of
gap>reps=List, - PreImagesRepresentative(acthom,
> Representative( x ) ) );;
]]<Example
<P/>
Then we carry <Example<[
,and compute classfusion centralizer
in <M>G</M>.
<P/gap =pi{ ;
<Example>!CDATA
gap> reps:= List( ccl, x -> PreImagesRepresentative( acthom,
>Representative(x )));
gap> fusion:= [];;
gap> centralizers:= [];;
gap> fusreps:= [];;
gap> for i in .( reps)] do
> found:= false;
> cen:157421875,121875,4875,475, 75, 3875, 475, 13000, 1750, 300, 400,
> for j in [ 1 .. Length( fusreps ) ] do
> if cen = centralizers[j] and
> IsConjugate( g, fusreps[j], reps[i] ) then
> fusion[i]:= j;
> found:= true;
> break;
> fi;
> od;
> if not found then
> Add( fusreps, reps[i] );
> Add( fusion 3060,15,,15 ,869,7 ,6
> Add( centralizers, cen );
> fi;
> od;
]]></Example>
<P/>
Next we compute the permutation character values,
using the formula
In order java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for length 0
classes in the &GAP; character table, we use the &GAP; function
<Ref Func="CompatibleConjugacyClasses" BookName=in these , we have consider :
<P/>
<Example><![CDATA[
gap> tblh:= CharacterTable( "O8+(2).S3" );;
gap> map:= containment the subgroup -java.lang.StringIndexOutOfBoundsException: Range [45, 46) out of bounds for length 45
gap> pi:= pi{
[ Now we consider the restrictions of this permutation character to 975, 135, 625, 150, 650, 30, 72, 80, java.lang.StringIndexOutOfBoundsException: Range [0, 41) out of bounds for length 37 12, 25, 484375, 1750, 375, 375, 30, 40, 15, 15, 15, java.lang.StringIndexOutOfBoundsException: Range [0, 55) out of bounds for length 49 157421875, 121875, 4875, 475, java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0 30, 60, 15, 15, 15, 125, gap : CharacterTable O+2.");
]]></Example>
<!-gap : pi{ (,tblh )};
<M>O^+_8(2).3</M>;
these cases,we wouldjava.lang.StringIndexOutOfBoundsException: Range [35, 34) out of bounds for length 58
element orders, centralizer orders,
centralizer orders of second and third power
containment in the derived subgroup. -->
<P/into<><M java.lang.StringIndexOutOfBoundsException: Range [50, 49) out of bounds for length 50
Now we consider the restrictionsin decomposition.
<M><M><>.2/M> MM3/>
Note that
<M>(1_H^G)_M = (1_M^S)_M</M>,
M(_G{M.2}=(_M.}{.)M2<M>
<M>(1_H^Gwhich than<>S:]/>
<P/>
<java.lang.StringIndexOutOfBoundsException: Range [9, 8) out of bounds for length 18
gap> tblm2:= CharacterTable( "O8+(2)
ap : CharacterTable "8+2.");
gap> tblm:= CharacterTable( "O8+(2)" );;
gap> pi_m2:= pi{ GetFusionMap( java.lang.StringIndexOutOfBoundsException: Index 36 out of bounds for length 11
gap> pi_m3:= pi{ GetFusionMap( tblm3, tblh )
gap> pi_m:= pi_m3{ GetFusionMap( tblm, tblm3 ) };;
]>/>
<P/>
character<>1_^S_M<M>decomposes
into <M>483on <>/<M>
and MM/>orbits on >S/> to regular constituents
in this M>1_{\langle g \rangl/ <M>_^_<M atjava.lang.StringIndexOutOfBoundsException: Range [62, 61) out of bounds for length 74
If there is no regular transitive constituent in <M>(1
the largest degree of a transitive constituent is <M>|M|/2</in<>/>.java.lang.StringIndexOutOfBoundsException: Index 13 out of bounds for length 13
but then the degree of <M>1_M^S</M>
whichsmallerthan >[:]M>.
<P/>
<Example><![CDATA[
gap> n:= inv:= Filtered .( tblm2 )]java.lang.StringIndexOutOfBoundsException: Index 58 out of bounds for length 58 483
> i in ClassPositionsOfDerivedSubgroup(tblm2 ) )java.lang.StringIndexOutOfBoundsException: Index 72 out of bounds for length 72 42065049600
gap> pi[1]; 51162109375
]]></Example>
<P/>
For the case of <M>M.2 < S.2</M>, this argument turns out to be not
sufficient.
So we first compute a lower bound on the number of java.lang.StringIndexOutOfBoundsException: Index 54 out of bounds for length 0
on <M>S/MList( java.lang.StringIndexOutOfBoundsException: Index 20 out of bounds for length 20
For involutions <M>g \in M</M ,15]
M1_{\angle r}^<M> M(_^S_M<M> is atmost integral
part
<M>1_gap>69 ( ) + - -1)*Size +1;
from this we compute that there are at most <M>208</M> such constituents.
<P/
<Example>P>
gap> inv:= Filtered( [ 1 .. URL>http://www.math.rwth-aachen.de/~Thomas.Breuer/ctbllib/data/o8p2s3_o8p5s3.g</URL>
> i ->P/>
[ 2, 3, 4, 5, 6 ]
gap> n2:= List( inv,
> - Int(2 [i] / SizesCentralizers )i]))java.lang.StringIndexOutOfBoundsException: Index 69 out of bounds for length 69
[ 1, 54, 54, 54, java.lang.StringIndexOutOfBoundsException: Range [9, 8) out of bounds for length 65
gap ( n2)java.lang.StringIndexOutOfBoundsException: Index 15 out of bounds for length 15 208
]]></Example>
<P/>
As ajava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
<M>S/M</M>.
Now we consider the action of <M>M.2</M> on <M>S.2/M.2</M>.
If <M>M.2</M> has no regular orbit then the <M>148</M> regular orbits of
<M>M</M> must arise from the restriction of transitive constituents
<M>1_U^{M.2}</M> to <M> <Ref =Identifier" BookName=BookName="ref"/>
and such that <M>U</M> is not contained in <M>M</M>.
(This follows from the fact that the restriction of a transitive constituent
of <M>(1_{M.2}^{S.2})_{M.2}<<><M is a
constituent of <M>(1_M^S)_M</M> or the sum of two such constituents;
the latter case occurs if and only if the point stabilizer is contained
in <M>M</M>.)
However, the number of these constituents is at most <M>134</M>.
<P/>
<Example><![CDATA[
gap> inv:= Filtered( [ 1 .. NrConjugacyClasses( tblm2 ) ],
> i -> OrdersClassRepresentatives( tblm2 )[i] = 2 and
> not i in ClassPositionsOfDerivedSubgroup( tblm2 ) );
[ 41, 42 ]
gap>n2=List(inv,
> i -> java.lang.StringIndexOutOfBoundsException: Index 20 out of bounds for length 7
[ 108, 26 ]
gap> Sum( n2 ); 134
]]></Example>
<!-- The number of <M>M.2-S.2-M.2</M> double cosets is <M>331</M>. -->
<P/>
Finally, we consider the action/Item
We compute that <M<Mark>Cjava.lang.StringIndexOutOfBoundsException: Range [16, 15) out of bounds for length 26
transitiveconstituents
and at most <M>69</M> permutations of degr of degree<></M>
This is already sufficient to show that there java.lang.StringIndexOutOfBoundsException: Range [0, 50) out of bounds for length 26
<<langle rjava.lang.StringIndexOutOfBoundsException: Index 48 out of bounds for length 48
<Example><![CDATA[
gap> n:= ScalarProduct( tblm3, pi_m3, TrivialCharacter( tblm3 ) );<tem><>cong</< 05
gap> inv:= Filtered(<>
>R>
[ 2, 3, 4 ]
gap> n2:= List( inv,
> i -> Int( 2 * pi_m3[i] / java.lang.StringIndexOutOfBoundsException: Index 40 out of bounds for length 5
[ 0, 54, 15 ]
gap ) 69
gap> 69 * Size( tblm3 ) / 2 + ( java.lang.StringIndexOutOfBoundsException: Range [5, 6) out of bounds for length 5 41542502401
pi[; 51162109375
]]></Example>
<><M regular constituents->
</Section>
<!-- %%%%%%%%%%%%%%%%%%%%%I<> _ , t \angle/><Itemjava.lang.StringIndexOutOfBoundsException: Index 54 out of bounds for length 54
<Section Label="sect:java.lang.StringIndexOutOfBoundsException: Index 33 out of bounds for length 0
<Heading>Appendix: The Data File</Heading>
contains the relevant data used in the above java.lang.StringIndexOutOfBoundsException: Index 57 out of bounds for length 5
This covers the representations for the groups
and the permutation character of <M>O^+_8(2).S_3</M>
computed in Section <Ref Subsect="sect:appendix_permchar"/Item<>M2/>/tem>I><>ong/M>/java.lang.StringIndexOutOfBoundsException: Range [50, 51) out of bounds for length 50
<P/>
eading the &; will definea global
<C>o8p2s3_o8p5s3_data</C>, a<><M> a_1,,c \angle<,/tem>
<P/>
<List>
<>>pi</C>/>
<Item<>l a_1 ,c,b\</,/tem>
the list of values of the permutation character of <M>G = O^+_8(5).S_3</M>
on the cosets of its subgroup <M>H = O^+_8(2).java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
restricted to <M>H</M>,
corresponding to the ordering of classes in the character table of <M>H</M>initial data, theconstructionsin the .
in the &GAP; Character Table Library
(
<orexample,mostof theneeded ariseas the
).3."C,
</these orbits are computed when the file is read,
<Mark><C>dim8Q</C></Mark>
Ijava.lang.StringIndexOutOfBoundsException: Index 6 out of bounds for length 6
a record with generators for <java.lang.StringIndexOutOfBoundsException: Range [0, 35) out of bounds for length 4
java.lang.StringIndexOutOfBoundsException: Range [13, 12) out of bounds for length 51
</Itemjava.lang.StringIndexOutOfBoundsException: Index 7 out of bounds for length 7
<Mark>d<java.lang.StringIndexOutOfBoundsException: Range [19, 18) out of bounds for length 26
<java.lang.StringIndexOutOfBoundsException: Index 6 out of bounds for length 6
a generatorsfor <MM><MM2<M>
permutations of degree <M>120</M>,
</Item>
<Mark><C>deg360</C></Mark>
<Item>
a record with generators for
<M>M</M>, <M>M.2</M>, <M>M.3</M>, and <M>H</M>,
permutations of degree <M>360</M>,
</Item>
<Mark><C>dim8f5</C></Mark>
<Item>
a record with generators for
<M>2.M</M>, <M>2.M.2</M>, <M>2.S</M>, and <M>2.S.2</M>,
matrices of dimension eight over the field with five elements,
</Item>
<Mark><C>deg19656</C></Mark>
<Item>
a record with generators for
<M>M</M>, <M>M.2</M>, <M>S</M>, and <M>S.2</M>,
permutations of degree <M>19\,656</M>,
</Item>
<Mark><C>deg58968</C></Mark>
<Item>
a record with generators for
<M>M</M>, <M>M.2</M>, <M>M.3</M>, <M>H</M>,
<M>S</M>, <M>S.2</M>, <M>S.3</M>, and <M>G</M>,
permutations of degree <M>58\,968</M>,
</Item>
<Mark><C>seed405</C></Mark>
<Item>
a block whose <M>H</M>-orbit in the representation on
<M>58\,968</M> points, w.r.t. the action
<Ref Func="OnSets" BookName="ref"/>,
yields a representation of <M>H</M> on <M>405</M> points.
</Item>
</List>
<P/>
For each of the permutation representations, we have (where applicable)
Additional components are used for deriving the representations from
initial data, as in the constructions in the previous sections.
<P/>
For example, most of the permutations needed arise as the induced actions
of matrices on orbits of vectors;
these orbits are computed when the file is read,
and are then stored in the components <C>orb120</C> and <C>orb19656</C>.
<P/>
The file <F>o8p2s3_o8p5s3.g</F> does not contain the generators
explicitly,
but it is self-contained in the sense that only a few &GAP; functions
are actually needed to produce the data;
for example, it should not be difficult to translate the contents of
the file into the language of other computer algebra systems.
<P/>
Advantages of this way to store the data are that the relations between
the representations become explicit,
and also that only very little space is needed to describe
the representations –the size of the file is less than <M>10</M> kB,
whereas storing (explicitly) one of the permutations on <M>58\,968</M> points
requires already about <M>350</M> kB.
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