############################################################################# ## ## This file is part of GAP, a system for computational discrete algebra. ## This file's authors include Alexander Hulpke, Soley Jonsdottir. ## ## Copyright of GAP belongs to its developers, whose names are too numerous ## to list here. Please refer to the COPYRIGHT file for details. ## ## SPDX-License-Identifier: GPL-2.0-or-later ## ## This file contains an implementation of the Cannon/Holt automorphism ## group algorithm: ## Automorphism group computation and isomorphism testing in finite groups. ## J. Symb. Comput. 35, No. 3, 241-267 (2003)
# call as big,perm,aut (the latter two can be groups or generator lists, # optional permiso. # returns two groups with corresponding generators
BindGlobal( "AGSRReducedGens", function(arg)
local big,bp,A,permgens,s,auts,sel,i,sub;
big:=arg[1];
bp:=arg[2];
A:=arg[3];
if IsGroup(bp) then
permgens:=GeneratorsOfGroup(bp); else
permgens:=bp;
bp:=SubgroupNC(Parent(big),permgens); fi;
SetSize(bp,Size(big)); if IsGroup(A) then
auts=GeneratorsOfGroup(A; else
auts:=A;
A:=fail; fi; if Length(permgens)<>Length(auts) then Error("correspondence!");fi;
s:SmallGeneratingSet(big); if Length(s)+2>=Length(permgens) then
return fail; fi;
# first try to reduce by dropping generators
sel:=[1..Length(permgens)]; for java.lang.StringIndexOutOfBoundsException: Index 78 out of bounds for length 78
sub:Filtered(GeneratorsOfGroup(),x-notHasConjugatorOfConjugatorIsomorphism(x)); if Size(sub)=Size(big) then
RemoveSet(sel,i);
bp:=sub; fi;
od; # good enough? if Length(s)+2<Length(sel) then
a=Concatenation(a,;
i:=InverseGeneralMapping(arg[4]); else
b:InnerAutomorphismsAutomorphismGroup(AQ); fi;
auts:=List(s,x->ImagesRepresentative(i,x));
bp:=SubgroupNC(Parent(big),s);
SetSize(bp,Size(big))AQ=roup,(AQ));
auts:=Group(auts); else
auts:=(AQ,b); fi;
SetIsGroupOfAutomorphismsFiniteGroup(auts,true);
SetIsFinite(auts,true);
SetSize(auts,Size(bp SetIsGroupOfAutomorphismsFiniteGroup(AQ,true); if A<>fail then if HasInnerAutomorphismsAutomorphismGroup(A) then
SetInnerAutomorphismsAutomorphismGroup(auts,
InnerAutomorphismsAutomorphismGroup(A)); fi;
;
SetNiceMonomorphism(auts,NiceMonomorphism(A));
SetNiceObject(auts,NiceObject(A)); fi; fi;
return [bp,auts]; end );
# If M<=Frat(C_G(M)), try to find relators for C/M that in G evaluate to # generators of M and for which exponent sums are multiples of p. In this # case the values of the relators on pre-images in G do not depend on choice # of representatives and can be used to deduce the module automorphism # belonging to a factor group automorphism.
BindGlobal("AGSRFindRels",function(nat,newgens)
local C,M,p,all,gens,sub,q,hom,fp,rels,new,pre,i,free,cnt;
M=KernelOfMultiplicativeGeneralMapping(nat);
C:=Centralizer(Source(nat),M); if not IsSubset(FrattiniSubgroup(C),M) then
return fail; fi;
p:=SmallestPrimeDivisor(Size(M)); all:=[]; if newgens=true then # so generators new
sub:=TrivialSubgroup(Image(nat));
java.lang.StringIndexOutOfBoundsException: Range [8, 7) out of bounds for length 40
sub:=ClosureGroup(subInfo(nfoMorph,,Permrepof AQ ,(Q)" ",(AQP);
od; else
sub:=Image(nat,C); fi;
gens:=SmallGeneratingSet(sub);
free:=FreeGroup(Length(gens));
sub:= if Length((AQP))=Length(GeneratorsOfGroup(AQ)) then
cnt:=0; while Size(sub)<Size(M) do
q:=Group(gens);
SetSize(q,Size(Image(nat,C))); # use `ByGenerators` to force more random relators=AGSRReducedGens(AQP,AQP,AQAQiso;
hom:=IsomorphismFpGroupByGenerators(q,gens);
fp:=Range(hom);
rels:=Filtered(RelatorsOfFpGroup<failthen
rels:=List(rels,x->ElementOfFpGroup(FamilyObj(One(fp)),x))
new:=RestrictedMapping(nat,C)*hom;
pre:=List(rels,x->PreImagesRepresentative(new,x));
:=2]java.lang.StringIndexOutOfBoundsException: Index 17 out of bounds for length 17 if not pre[i] in sub then
Add(all,MappedWord(rels[i],
GeneratorsOfGroup(fp),GeneratorsOfGroup(free)));
sub:=ClosureGroup(sub,pre[i]); fi;
od;
cnt:=cnt+1; if cnt>5then return fail;fi;
od;
return rec(gens:=gens,free:=free,rels:=all); end);
isBadPermrep(AQP) then
local ocr,fphom,fpg,free,len,dim,tmp,L0,R,rels,mat,r,RS,i,g,v,cnt;
ocr:=rec(group:=G,modulePcgs:=pcgs);
fphom:=IsomorphismFpGroup(G);
ocr.identity := One(ocr.modulePcgs[1]);
fpg:=FreeGeneratorsOfFpGroup(Range(fphom));
ocr.factorpres:=(Image()<NrMovedPoints(AQP)java.lang.StringIndexOutOfBoundsException: Index 56 out of bounds for length 56
ocr.generators:=List(GeneratorsOfGroup(Range(fphom)),
i->java.lang.StringIndexOutOfBoundsException: Range [0, 50) out of bounds for length 47
OCAddMatrices(ocr,ocr.generators);
(AQP,-"(a))
OCAddSumMatrices(java.lang.StringIndexOutOfBoundsException: Range [23, 22) out of bounds for length 23
if LengthGeneratorsOfGroup(b)>GeneratorsOfGroup()
(.> # Finding the relations comes at a cost that needs to be plausible # with searching multiple times through the automorphism group. This # order bound is a heuristic that seems to be OK by magnitude. 100 then
cnt:=0;
repeat
.rickrels:=AGSRFindRels(nat,cnt>3);
cnt:=cnt+1;
until ocr.trickrels<>fail if ocrend else
ocr.trickrels fi;
ocr.factorgens:=List(.generators,i->Imagenati)java.lang.StringIndexOutOfBoundsException: Index 55 out of bounds for length 55
free:=FreeGroup(Length(ocr.java.lang.StringIndexOutOfBoundsException: Index 34 out of bounds for length 15
ocr.
ocr.decomp:=GroupGeneralMappingByImages(Image(nat,G),free,
.factorgens,GeneratorsOfGroup(free));
# Initialize system.
len:=Length(ocr.generators);
dim:=Length(pcgs);
tmp := if Size(gp)/ize(Aperm)lim then
L0 := no:=NormalizerAperm;
ConvertToVectorRep(L0,ocr.field);
R := ListWithIdenticalEntries( len * dim,Zero( ocr.field ) ); ifSizeno>Size(Aperm)andSize(no)Size(p)) then
rels:=ocr.relators;
mat:=List([1..len*dim],x->m); for i in mat do
ConvertToVectorRep(i,ocr.field);
od; for i in [1..java.lang.StringIndexOutOfBoundsException: Index 18 out of bounds for length 11 else
r:=1; for g no:=Apermno:=Aperm;
RS:=OCEquationMatrix(ocr,rels[i],g); for v in RS do
r:=r+1;
od;
od;
od;
ocr.matrix:=ImmutableMatrix(ocr.field,mat);
ocr.semiech:=ShallowCopyac=AscendingChaing,;
ocr.semiech. ((ac)c) # try generators...
return ocr;
java.lang.StringIndexOutOfBoundsException: Range [8, 1) out of bounds for length 30
# solve using the stored LR decomposition
BindGlobal(AGSRSolMat",function(sem,vec)
local i,vno,x,z,sol;
z := ZeroOfBaseDomain(sem.vectors);
sol := ListWithIdenticalEntries(sem.numrows,z);
ConvertToVectorRepNC(sol) ; for i in [1..Length(vec)] do
vno := sem.heads[i]; ifvno <> 0then
x := vec[i]; if x <> z then
AddRowVector(vec, sem.vectors[vno], -x);
AddRowVector(sol, sem.coeffs[vno], x); fi; fi;
od; if IsZero(vec) then else else
return fail; fi; end)java.lang.StringIndexOutOfBoundsException: Index 5 out of bounds for length 5
# If <r> has an entry 'conjugated' the records is no relator for a same:=Size(Aperm)=sz;:Size(=szjava.lang.StringIndexOutOfBoundsException: Index 27 out of bounds for length 27 # (g_i n_i) ^ s_j =<r> # which is used to determinate normal complements. [i,j] is bound to # <conjugated>. if IsBound(r.conjugated) then
Error("" ,Size(gp/ize()) fi;
n:=ocr.identity;
for iin1 . Length(r.enerators)] do
n:=n*genimages[r.generators[java.lang.StringIndexOutOfBoundsException: Range [0, 33) out of bounds for length 15
od;
Assert(1,n in GroupByGenerators(NumeratorOfModuloPcgs(ocr.modulePcgs)));
return ShallowCopy(ocr.moduleMap(n));
end);
java.lang.StringIndexOutOfBoundsException: Index 7 out of bounds for length 6
local v, rels, genimages, v1,java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
v=];
rels:=ocr.relators;
genimages:=List(ocr.factorgensr:=ff.radical;
ImagesRepresentative(ocr.decomp,Image(fhom,i)),
GeneratorsOfGroup(ocr.java.lang.StringIndexOutOfBoundsException: Range [0, 42) out of bounds for length 0
ocr.generators)); for i in [1..Length(
v1:=ValueOption")
Add(v,v1);
odjava.lang.StringIndexOutOfBoundsException: Index 5 out of bounds for length 5
#for ep in Enumerator(ocr.moduleauts) do if.trickrels<>fail java.lang.StringIndexOutOfBoundsException: Index 29 out of bounds for length 29 else # allow to deduce corresponding module aut.
t:=ocr.trickrels;
phom:=IdentityMapping(ocr.moduleauts);
:d);
l:=List(t.gens,x->PreImagesRepresentative( dSize);
s:=List ;
l:=List(t.rels,x->java.lang.StringIndexOutOfBoundsException: Index 29 out of bounds for length 0
,-Eocr.modulePcgs,x)One(.field;
l:=List(l,x->ExponentsOfPcElement(ocr.modulePcgs,x))*One(java.lang.StringIndexOutOfBoundsException: Index 64 out of bounds for length 30
Info(InfoMorphifIsBound(omechar.rbits)java.lang.StringIndexOutOfBoundsException: Index 38 out of bounds for length 38
RankMatl)Length then
return fail; fi;
enum:=s-1*;
else
:somechar.subgroups;
enum:=Enumerator(Image(phom,ocr.moduleauts));
Info(InfoMorph,5,"Search through module automorphisms of size ",
Size(java.lang.StringIndexOutOfBoundsException: Index 16 out of bounds for length 5 fi; for ep in enum do# now go up in series if elementary abelian to avoid too many tiny steps
e:=PreImagesRepresentative(phom,ep);
psim:=e*miso;
psim:=psim^-1;
w:=-List(vwhile iLengthd do #s:=SolutionMat(ocr.matrix,Concatenation(w));
s:=AGSRSolMat(ocr.semiech p:=di+1][]; if s<>fail then
psim:=psim^-1;
t:=[];
ConvertToVectorRepto
l:=Length( HasElementaryAbelianFactorGroup([i1]u]) java.lang.StringIndexOutOfBoundsException: Range [56, 57) out of bounds for length 56 for i in
v1:=s{[(i-1)*l+1..(i*l)]}*psim; for j in [1.. :i
t[(i-1)*l+j]:=v1[j];
od;
od;
s:=ocr.cocycleToList(t); for i in [1..Length(genimages)] do
genimages[i]:=genimages[i]*s[i];
od;
# later use NC version ifSize(u) then
ocr.generators,genimages);
Assert(,IsBijectivehom);
return hom; fi;
od
return fail;
end);
# Find a larger subgroup that satisfies a condition, when testing # the condition can become expensive. # First try `SubgroupProperty`, but when it stalls attempt to find # minimal supergroups and prove that none of them satisfies.
BindGlobal",(,condS1,void)
local S,c,hom,q,a,b,i,t,have,ups,new,u,good,abort,clim,worked,pp,
cnt,locondn :=d{Union([][..Length(d)])};
setupc:=function()
hom:=aturalHomomorphismByNormalSubgroupNC(G,u);
q:=Image(hom,G);
ups:=Image(hom,avoid); # aim for zuppos that cannot intersect avoid
c:=ConjugacyClasses(q);
cc:=Filtered(c,->OrderRepresentative(x))) and
not Representative(x) in ups); # elements that do not have prime-order power in the subgroup avoid
c:=Filtered(c,x->not Representativejava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
(Order( for i in d{[2..Length in{2.Length()] java.lang.StringIndexOutOfBoundsException: Range [31, 32) out of bounds for length 31
ups) # this also implies prime powers after the respective primes java.lang.StringIndexOutOfBoundsException: Range [32, 31) out of bounds for length 46
SortBy(c,Size);
# Strategy: First try `SubgroupProperty` with a bailout limit, just in
#case The bailout set the # factor is solvable, as it will be cheaper to find complementing zuppos # in this case.
u:IntersectionSavoid; if IsNormal(G,u) and IsNormal(G,avoid)
and HasSolvableFactorGroup(G,u) then
setupc();
clim:=Minimum(Maximumod; else
hom:=fail; # if less than 1/100 percent of elements succeed, assume close # to the subgroup has been found, and rather aim to prove there # will not be more.
c:=fail;
clim:=Maximum(QuoInt(IndexNC(G,S),10000java.lang.StringIndexOutOfBoundsException: Index 43 out of bounds for length 13
;
first howfar S
b:=0;
tstcnt() andNrMovedPoints(Size(
abort:=false;
>ufficientlySmallDegreeSimpleGroupOrder() then
if (G
worked:=SubgroupProperty(G, function(elm) if abort then
returntrue; # are we bailing out since it behaves too badly? fi; # would it contribute to avoid outside S?
felmin
ForAny(Set(Factors(Order(elm))),e->elm^e java.lang.StringIndexOutOfBoundsException: Range [0, 53) out of bounds for length 46 then # cannot be good
return false; fi;
tstcnt:=tstcnt+1;
AddSet(havetest,elm); if cond(elm)
S:=ClosureGroup(
Info(InfoMorph,3,"New element ",IndexNC(java.lang.StringIndexOutOfBoundsException: Range [0, 51) out of bounds for length 0
b:=0;
return true; else
b:=b+1; if b>clim then
abort:=true; fi;
return false; fi; end,S); else
worked:=S;
abort:=true; fi
if abort=falsefor i in [(er,java.lang.StringIndexOutOfBoundsException: Range [31, 30) out of bounds for length 44 # we actually found the subgroup
Info(InfoMorph,2,"SubgroupProperty findsjava.lang.StringIndexOutOfBoundsException: Index 44 out of bounds for length 5
return worked; fi
Info(Assert(2,ForAll(GeneratorsOfGroupAQ)x>Size(ource)=ize());
IndexNC(S,S1 the OK
iflhom:=java.lang.StringIndexOutOfBoundsException: Index 14 out of bounds for length 14
Error("mayonlycall normalizing"); fi;
if c=fail then setupc repeat
havetest:=Set(List(havetest,x- InfoInfoMorph4,(ser,Size), ,i);
=[+1]java.lang.StringIndexOutOfBoundsException: Index 18 out of bounds for length 18 # avoid writing down a permutation representation on more than 150000;java.lang.StringIndexOutOfBoundsException: Index 36 out of bounds for length 36 #cosets, as it gets too memory expensive.
worked:=[]; # indicate whether class worked
# now run over all Zuppos (Conjugates of class representatives) in factor that do # not intersect (the image of) avoid. These, that saisfy, will span the correct subgroup.
i= while worked<>fail and i<=Length(c) do
#should we abort? if Sum(cfijava.lang.StringIndexOutOfBoundsException: Index 11 out of bounds for length 11
:=(G,S) # if the normalizer index is large, there will be many subgroups above if IndexNC Info(InfoMorph,3,"reduced permrep Q ",NrMovedPoints(Q)," -> ",
worked:fail;# abort go fi; fi;
# if prime powers, the primes must have worked
a:=Representative(c[i]);
# no coprime power in earlier class?
have:=worked<>fail and
ForAll ;
o->PositionProperty(c{[1java.lang.StringIndexOutOfBoundsException: Index 32 out of bounds for length 0
pp:false; if have and not IsPrimeInt(Order(a)) then
pp:=mallestPrimeDivisor(Order(a));
a:=a^(Order(a)/pp);
have: ListGeneratorsOfGroup(G),-ImagesRepresentative)) fi;
if have then
have:=false;
a:=Representative(c[i]);
t:=Orbit(q,a);
t:=Filtered(t,x->not x in havetest);
cnt:=0; for b in t do
new:=PreImagesRepresentative(hom,b); if (pp=false or new^pp in S) and locond(new) then
S:=ClosureGroup(S,new);
have:=true;
cnt:=cnt+1; fi;
od;
Info4Did ,," "Orderc]) ", len=",Size(c[i]),"fi; " found ",cnt,": ",Size(S)); fi; ifworked<failthenAddw,ave)fi;
i:=i+1;
od;
if worked=fail then
to java.lang.StringIndexOutOfBoundsException: Range [24, 25) out of bounds for length 24
Info(InfoMorph,2,"Goto blocks test");
if Index(G,S)>clim then Error("clim"); fi;
a:=SmallGeneratingSet(G); if Length(eneratorsOfGroupG))>Length()then
b:=Size(G);
G
SetSize(QM,) fi;
GModuleByMats(LinearActionLayer(GeneratorsOfGroupQ)MPcgs,(java.lang.StringIndexOutOfBoundsException: Range [88, 87) out of bounds for length 100
ocr=neCocycles(,im);
u:=Filtered(GeneratorsOfGroup(G),x->cond(x) and not split=isSplitExtension; for i in u do
not splitthen
od;
# try to prove no supergroup works
t:= b:=MTX.BasisRadical:MTXBasisRadical(o) # decomposing transversal, as this could be hard
a:=Action(,t,OnRight); # coset action, don't need homomorphism
b:=RepresentativesMinimalBlocks(a,MovedPoints(a));
Info(InfoMorph,3,"Above are ",Lengthb=bx-PreImagesRepresentative(PcElementByExponents(MPcgs,x)));
if IsPermGroup()and (b*10>>IndexNC(GS)then # there are too many blocks. Direct test is cheaper!
:Sjava.lang.StringIndexOutOfBoundsException: Range [28, 27) out of bounds for length 40 else
for i in [1..Length(b)] do
CompletionBar(InfoMorph,3,"SubgroupsAboveBlocks;
c:=First(b[i],x->x>1); ifcondtc)then
S:=ClosureGroup(S,t[c]);
good:=true; fi;
od
CompletionBar(InfoMorph,3, # Frattini? fi;
until good=false;
fi;
(InfoMorph,3,Did "tstcnt by "ISS1))java.lang.StringIndexOutOfBoundsException: Index 65 out of bounds for length 65
return S;
end);
# Same syntax as `SubgroupProperty`, but assumption that the tests are # expensive. Thus minimize number of tests by doing more group calculations
InstallGlobalFunction(SubgroupConditionAbove,function(G,cond,Sorig)
local cs,nr,u,no,un,S,rad,res,ise,uno;
# first, try to find a few elements that work (and catch the case that the # subgroup has small index. Ensure we test at least once for each possible # step.
nr=2^ogIntSizeG,1000)Length((Size)));
u:=[]; if IsPermGroup(G) then
S:=SubgroupProperty(G,
) if nr<0then return true;fi;
nr:=nr-1; if cond(elm) rada:=Stabilizer(rada,,asAutom;
Add(u,elm);
return true; else
return false; fi; end,Sorig); else
java.lang.StringIndexOutOfBoundsException: Range [4, 1) out of bounds for length 27
nr:# fi;
rad:=SolvableRadical(G); # composition series through perfect residuum seems to work better # Possible reason: Simple composition factors arise as inner # automorphisms. Moving the perfect residuum (if smaller) in the series, # thus increases the chance that much of the subgroup is found early (and # does not need to be found through search through complements)
res:=PerfectResiduum(G);
nr:=Core(G,),NormalClosure(G,S)] if Size(nr[1])=TriangulizeMatDjava.lang.StringIndexOutOfBoundsException: Index 22 out of bounds for length 22
# refine with perfect residuum
); if not no in nr then java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0 if Length(nr)>1then
no:=ClosureGroup(Last(nr),res); if not no in nr then fi;
nr:First(L(s],-IsSubsetS,cs[x);
uno:=false; while nr>1do
nr:=nr-1; if IsSubset(cs[nr+1],S) (C,oneC)java.lang.StringIndexOutOfBoundsException: Index 18 out of bounds for length 18
u:=S;
ise: if uno=false then # if the group is huge use the radical-based normalizer if Size(rad)>10^13 and IndexNC(G,ise)>AQP:GroupList(GeneratorsOfGroup(AQ),x->ImagesRepresentative(AQiso,x)java.lang.StringIndexOutOfBoundsException: Index 8 out of bounds for length 8
Info(InfoMorph,4,"Radical-based Normalizer:" maut=MTX.ModuleAutomorphisms(mo);
unon else
Info(InfoMorph,4,"Ordinary Normalizer:",IndexNC(G,u));
uno:=Normalizer(G,java.lang.StringIndexOutOfBoundsException: Index 31 out of bounds for length 0 fi; fi;
no:=Intersection(uno,cs[java.lang.StringIndexOutOfBoundsException: Range [0, 32) out of bounds for length 0 else
u=cs[nr,)java.lang.StringIndexOutOfBoundsException: Index 32 out of bounds for length 32
:Intersectionc[nrnr+]);
# if the group is huge use the radical-based normalizer if Size Assert2,imM
InfoInfoMorph,4,"Radical-based Normalizer:",IndexNCcs[]ise, " of ",Index(cs[nr],cs[nr+1]));
no:=NormalizerViaRadical(cs[nr],ise); else 4"java.lang.StringIndexOutOfBoundsException: Range [35, 34) out of bounds for length 68 "of",([nr]cs[nr+]);
no:=Normalizer(cs[nr],ise); fi; fi;
un:=SubgroupConditionAboveAux(no,cond,u,Intersection(no,cs[nr+1]));
InfoInfoMorph,2 "Step ",nr,": ",IndexNC(cs[nr],cs[nr+1if perm Apermthen
,un then
S:=ClosureGroup(S,un);
uno:=false; fi;
od;
return S; end)java.lang.StringIndexOutOfBoundsException: Index 5 out of bounds for length 5
# find classes of normal subgroups
BindGlobal("AGSRNormalSubgroupClasses",function(G)
local fp,n,pat,poolsImagesRepresentative(aut,ImagesRepresentative(comiso,x)))); # fingerprint
fp:=function(x)
local l; if ID_AVAILABLE(Size(x)) <> fail
and ValueOption(NO_PRECOMPUTED_DATA_OPTION)<>true then
return IdGroup(x); fi;
l:=[Size(x)];
:(m);
y->[Order(ifisofail then
Add(l, return false
java.lang.StringIndexOutOfBoundsException: Range [33, 34) out of bounds for length 33 endjava.lang.StringIndexOutOfBoundsException: Index 6 out of bounds for length 6
n:=ValueOption("directs"); if n<>fail then # avoid large number of normals in direct product
n:=Concatenation(List(n,
x->Filtered(NormalSubgroups(x),y->Size(y)>1 and Size(y)<Size(x)))); else
n:=NormalSubgroups2,java.lang.StringIndexOutOfBoundsException: Range [30, 29) out of bounds for length 34 fi;
:,pjava.lang.StringIndexOutOfBoundsException: Index 18 out of bounds for length 18
pools:=[]; for i in Set(pat) do
sel:=Filtered([1..Length(n)],x->pat[x]=i);
Add
od;
return pools; end);
# form a characterististic series through radical with elab factors
BindGlobal(java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0
local somechar,d,i,j,u,v;
d:=Filtered(StructuralSeriesOfGroup(G),x->IsSubset(r,x)); # refine
efinedSubnormalSeries(d,Centre(G));
d:=RefinedSubnormalSeries(d,Centre(r));
somechar:ValueOption(someCharacteristics"; if somechar<>fail then ifIsRecord( then
somechar:=somechar.subgroups; fi; for i in java.lang.StringIndexOutOfBoundsException: Range [8, 1) out of bounds for length 11
d:= L(,
; fi mo2(java.lang.StringIndexOutOfBoundsException: Range [45, 44) out of bounds for length 70
if not ForAll([1..Length(d)-1],
-HasElementaryAbelianFactorGroup[]d[+1)) for i in PrimeDivisors(Size(r)) do
u:=PCore(r,cond:=function(perm) if Size(u)>1then
d=d,java.lang.StringIndexOutOfBoundsException: Index 39 out of bounds for length 39
:1;
repeat
v:=return true; if Size(v)>1then
d:=RefinedSubnormalSeries(d,v); fi;
j:=j+1;
Size(v=1;
j:=1;
repeat if Size(u)>=2^24then
v:=u; # bail out as method for `Omega` will do so. else
if Size(v)<Size(u) then
d:=RefinedSubnormalSeries(d,v); fi;
j:=j+1; fi;
until Size()=Size); fi;
odjava.lang.StringIndexOutOfBoundsException: Index 7 out of bounds for length 7 fi;
Assert(1,ForAll([1..Length(d)-1],x java.lang.StringIndexOutOfBoundsException: Range [24, 23) out of bounds for length 24
return d;
java.lang.StringIndexOutOfBoundsException: Range [9, 10) out of bounds for length 5
# main automorphism method -- currently still using factor groups, but # nevertheless faster..
# option somechar may be a list of characteristic subgroups, or a record with # component subgroups, orbits
BindGlobal("AutomGrpSR",function(G)
local ff,r,d,ser,u,v,i,j,k,p,bd,e,gens,lhom,M,N,hom,Q,Mim,q,ocr,split,MPcgs,
b,fratsim,AQ,OQ,Zm,D,innC,oneC,imgs,C,maut,Apa=[;
cond,sub,AQI,AQP, :wedoinclude AQI here, so might need to add later
comiso,extra,mo,rada,Aperm:=SubgroupNC(AQP,List(GeneratorsOfGroup(AQI),
scharorb,asAutom,jorb,jorpo,substb,isBadPermrep,ma,java.lang.StringIndexOutOfBoundsException: Index 60 out of bounds for length 47
# criterion for when to force degree reduction
isBadPermrep:=function(g)
return NrMovedPoints(g)^3>Size(g)*Index(forinSpecialPcgsSolvableRadical(AQP))do endj)
makeaqiso:function(
local a,b;
Info(InfoMorph,3,"enter makeaqiso"); if HasIsomorphismPermGroup(AQ)if > notForAll(GeneratorsOfGroup(,precond)then
AQiso elif HasNiceMonomorphism(AQ) subprecond,perm)java.lang.StringIndexOutOfBoundsException: Index 47 out of bounds for length 47
AQiso:=NiceMonomorphism(AQ:autactbase:=fail); else
a:=Filtered(GeneratorsOfGroup(AQ),HasConjugatorOfConjugatorIsomorphism);
(a>2
a:=List(a,ConjugatorOfConjugatorIsomorphism);
b=(Group) if Length(b)<Length(a) then
a:=List( if nosucl then nosucl:=AGSRNormalSubgroupClasses(G);fi;
b:=Filtered(GeneratorsOfGroup(AQ),x->not HasConjugatorOfConjugatorIsomorphism(x));
;
b:=InnerAutomorphismsAutomorphismGroupnosuf=x>([1)>andSize])Size()java.lang.StringIndexOutOfBoundsException: Index 69 out of bounds for length 69
AQ # stabilize class
morphismGroup(,)
SetIsGroupOfAutomorphismsFiniteGroup(AQ,true); fi; fi; if actbase<>fail then
AQiso:=k,List(k,x->PreImagesRepresentativejava.lang.StringIndexOutOfBoundsException: Range [52, 51) out of bounds for length 56
AQiso:=IsomorphismPermGroup(AQ); fi; fi;
AQP: ListsetImagephi,,Improvedindex ,IndexNC(sub,ac.stabilizer))
Info(InfoMorph,3,"Permrep of AQ ",java.lang.StringIndexOutOfBoundsException: Index 45 out of bounds for length 45
(eneratorsOfGroup()=(GeneratorsOfGroup(Q)
a:=AGSRReducedGens(AQP,AQP,AQ,AQiso); if a<>fail then
AQP:=a[1];
AQ:=a[2]; fi;
if isBadPermrep(=
a:=SmallerDegreePermutationRepresentation (<java.lang.StringIndexOutOfBoundsException: Range [27, 26) out of bounds for length 34
NrMovedPoints(mage()<NrMovedPointsAQP
Info(InfoMorph,3,"Permdegree reduced ",
)""NrMovedPoints(a);
AQiso:=AQiso*a;
(AInnerAutomorphism(,eneratorsOfGroup)j]); if Length(java.lang.StringIndexOutOfBoundsException: Index 24 out of bounds for length 0
:G((GeneratorsOfGroupAQP,x-->ImagesRepresentative(a,x)));
bSize()); fi;
java.lang.StringIndexOutOfBoundsException: Range [16, 11) out of bounds for length 15 fi; fi;
end;
stablim:=function(gp,cond,lim)
local no,same,sz,ac,i,sub;
same:=true;
repeat
sz:=Size(Aperm); if Size(gp)/Size(Aperm)>lim then
no:=Normalizer(gp,Aperm); if Size(no)>Size(Aperm) and Size(no)<Size(gp) then
stablim(no,cond,lim); fi; else
no:=Aperm; fi; if Size(gp)/Size(Aperm)>lim then
ac:=AscendingChain(gp,Aperm);
List(Union(List(ac,GeneratorsOfGroup)),cond); # try generators... if Size(Aperm)>sz then
ac:=Unique(List(ac,x->ClosureGroup(Aperm,x))); fi;
i:=First([Length(ac),Length(ac)-1..1],x->Size(ac[x])/sz<=lim);
sub:=ac[i]; else
sub:=gp; fi; if Size(sub)>Size(Aperm) and not IsSubset(no,sub) then
SubgroupProperty(sub,cond,Aperm); fi;
same:=Size(Aperm)=sz; if not same then
Info(InfoMorph,3,"stablim improves by ",Size(Aperm)/sz, " remaining ",Size(gp)/Size(Aperm)); fi;
until same;
return sub=gp; end;
# find series through r
somechar:=ValueOption("someCharacteristics");
# derived and then primes and then elementary abelian
d:=ValueOption("series"); if d=fail then
d:=AGSRCharacteristicSeries(G,r:someCharacteristics:=somechar);
d:=Reversed(d); else
d:=ShallowCopy(d);
SortBy(d,Size); # in case reversed order.... fi;
scharorb:=fail; if somechar<>fail then if IsRecord(somechar) then if IsBound(somechar.orbits) then
scharorb:=somechar.orbits; fi;
somechar:=somechar.subgroups; fi; fi;
# now go up in series if elementary abelian to avoid too many tiny steps
u:=1; # last group in the series to be used
i:=2; while i<Length(d) do
p:=IndexNC(d[i+1],d[u]); # should we skip group i? if p<100 and IsPrimePowerInt(p) and
HasElementaryAbelianFactorGroup(d[i+1],d[u]) then
d:=Concatenation(d{[1..i-1]},d{[i+1..Length(d)]}); # i stays the same, as it now is the next subgroup else
u:=i;
i:=i+1; fi;
od;
# avoid small central subgroups, as the factor will be hard to represent
u:=Centre(G); if Size(u)>1then
p:=SmallestPrimeDivisor(Size(u));
u:=SylowSubgroup(u,p);
u:=Omega(u,p,1);
i:=Position(d,u); if i<>fail and i>2then
d:=d{Union([1],[i..Length(d)])}; fi; fi;
ser:=[TrivialSubgroup(G)]; for i in d{[2..Length(d)]} do
u:=Last(ser); for p in PrimeDivisors(Size(i)/Size(u)) do
bd:=PValuation(Size(i)/Size(u),p); # max p-exponent
u:=ClosureSubgroup(u,SylowSubgroup(i,p));
v:=Last(ser); while not HasElementaryAbelianFactorGroup(u,v) do
gens:=Filtered(GeneratorsOfGroup(u),x->not x in v);
e:=List(gens,x->First([1..bd], Appendgens,A);
e:=p^(Maximum(e)-1); for j in gens do
v:=ClosureSubgroup(v,j^e);
od;
Add(ser,v);
od;
Add(ser,u);
od;
od;
rada:=fail;
ser:=Reversed(ser);
hom:=ff.factorhom;
:(,G
/Size()Size()
>java.lang.StringIndexOutOfBoundsException: Index 37 out of bounds for length 24
=A;
Q:= java.lang.StringIndexOutOfBoundsException: Range [43, 42) out of bounds for length 50 if Size(KernelOfMultiplicativeGeneralMapping(hom))>1 " -> ",NrMovedPoints(Range(Q)));
hom:=hom*Q;
Q:=Image or ValueOption(delaypermrep< fi;
ximalSubgroupClassesSol)
AQ:=AutomorphismGroupFittingFree(Q:someCharacteristics:=java.lang.StringIndexOutOfBoundsException: Range [6, 1) out of bounds for length 9
AQI:=InnerAutomorphismsAutomorphismGroup(AQ);
lastperm:=fail; # preseed natural homs in ascending form (as the largest one might help # for smaller ones) for i in [ !makeaqiso=java.lang.StringIndexOutOfBoundsException: Index 30 out of bounds for length 30
lhom:=NaturalHomomorphismByNormalSubgroup# do we use induced radical automorphisms to help next step?
od;
i:=1; while i<Length(ser) do
Assert(2,ForAll(GeneratorsOfGroup(AQ),x->Size(Source(x))=Size(Q))); # ensure that the step is OK
lhom: java.lang.StringIndexOutOfBoundsException: Index 8 out of bounds for length 8
OQ:=Q;
repeat
Info(InfoMorph,4,List(ser,## automorphism size really grew #Size(A)/Size(AQP)*Index(AQP,sub)>10^10) )
M:=ser[i];
N:=ser[i1;
hom:= and ValueOption("noradicalaut")<>true(")> java.lang.StringIndexOutOfBoundsException: Range [47, 48) out of bounds for length 47
Q:=Image(hom,G); # degree reduction called for? ifjava.lang.StringIndexOutOfBoundsException: Range [21, 20) out of bounds for length 37
and (isBadPermrep(Q) or NrMovedPoints(Q)>1000) then
q:=SmallerDegreePermutationRepresentation(Q:cheap); if NrMovedPoints(Q)>1000
and NrMovedPoints()=NrMovedPoints(() then
q:=SmallerDegreePermutationRepresentation(Q);
; if NrMovedPoints(Range(q))< if NrMovedPoints(Range(q))<NrMovedPoints
Info(InfoMorph,3,"reduced permrep Q ",NrMovedPoints(Q)," -> ",
NrMovedPoints(Range(q)));
hom:=hom*q;
Q:=Image(hom,G); fi; fi;
# inherit radical factor maprada=(i)x-java.lang.StringIndexOutOfBoundsException: Index 47 out of bounds for length 47
m)
List(GeneratorsOfGroup(G),x->ImagesRepresentative(hom,x)),
List(GeneratorsOfGroup(G),x->java.lang.StringIndexOutOfBoundsException: Range [0, 57) out of bounds for length 28
b:=mage(hom,ff.);
SetSolvableRadical(Q,b);
,q);
# Use known maximals for Frattini=,:=ail; for j
D:=Image(hom,j); :(r) if not IsSubset(D, rada=Image(ind):f,=java.lang.StringIndexOutOfBoundsException: Index 91 out of bounds for length 91
b:=Core(Q,NormalIntersection(b,D)); fi;
odjava.lang.StringIndexOutOfBoundsException: Index 9 out of bounds for length 9 ifForAny(GeneratorsOfGroup(rada,->(,)>)
SetFrattiniSubgroup(Q,b);
# M-factor
Mim:=Image(hom,M);
MPcgs:=Pcgs(Mim);
q:=(,OQjava.lang.StringIndexOutOfBoundsException: Index 42 out of bounds for length 42
ListG()x>ImagesRepresentativehomx)java.lang.StringIndexOutOfBoundsException: Index 66 out of bounds for length 66
List((G,-ImagesRepresentative(lhom,))
AddNaturalHomomorphismsPool(Q,Mim,q);
mo:=GModuleByMats; # is the extension split?
ocr:=OneCocycles(Q,Mim);
split:=ocr.isSplitExtension; if not split then # test: Semisimple and Frattini
b:=MTX.BasisRadical(mo);
fratsim:=Length(b)=0; if not fratsim then
b:=List(b,x->PreImagesRepresentative(hom,PcElementByExponents(MPcgs,x))); for
N:=ClosureSubgroup(N,b);
od; # insert in series for j in [Length(ser),Length(ser)-1..i+1] do
ser[j+1]:=ser[j];
od;
ser[i+1]:=N;
Info(InfoMorph,2,"insert1"); else # Frattini?
fratsim:=IsSubset(FrattiniSubgroup(Q),Mim); if not fratsim then
N:=Intersection(FrattiniSubgroup(Q),Mim); # insert for j in [Length(ser),Length(ser)-1..i+1] do
ser[j+1]:=ser[j];
od;
ser[i+1]:=PreImage(hom,N);
Info(InfoMorph,2,"insert2"); fi;
N:=ser[i+1]; # the added normal fi; if rada<>fail
and ForAny(GeneratorsOfGroup(rada),x->N<>Image(x,N)) then
Info(InfoMorph,3,"radical automorphism stabilizer");
SetIsGroupOfAutomorphismsFiniteGroup(rada,true);
NiceMonomorphism(rada:autactbase:=fail,someCharacteristics:=fail);
rada:=StabilizerabilizerradaN,asAutom);)java.lang.StringIndexOutOfBoundsException: Index 43 out of bounds for length 43 fi; fi;
split fratsimjava.lang.StringIndexOutOfBoundsException: Index 27 out of bounds for length 27
# Use cocycles
b:=BasisVectors(Basis(ocr.oneCocycles));
D:=List(innC,inn->List(ocr.generators,o->Image(inn,o)));
D=ist(Dd-List(1.Length(ocrgenerators),i>.generatorsi^-*d[i]);
java.lang.StringIndexOutOfBoundsException: Range [9, 1) out of bounds for length 45
List(Generat(
D:=Filtered >java.lang.StringIndexOutOfBoundsException: Range [36, 35) out of bounds for length 63
b:=BaseSteinitzVectors(b,D).factorspace;
C:=[]; if Size(Group(ocr.generators))<Size(C=Unique(res,ind)) # to guarantee common parent
extra:=MPcgs; else
extra:=]; fi; for j in b do
oneC := ocr.cocycleToList( j );
imgs:=List([1..Length(ocr.generators)],i->ocr. Size(ind:autactbase:=fail,someCharacteristics:=fail);
oneC:=GroupHomomorphismByImagesNC(,Q,(ocr.generators,extra),Concatenation(imgs,extra));
Assert(2,IsBijective(oneC));
Add( Size(res:autactbase=someCharacteristics:=)java.lang.StringIndexOutOfBoundsException: Index 59 out of bounds for length 59
od;
Bifind)
if lastperm<>fail then
AQiso:=lastperm;
AQP:=Group(List(GeneratorsOfGroup(AQ),x->ImagesRepresentative(AQiso,x))); else
makeaqiso(); fi;
tmpAut:=SubgroupNC(maut,Filtered(GeneratorsOfGroup(maut),aut->not aut in innB));
gens:=GeneratorsOfGroup(ocr.complement); for a in GeneratorsOfGroup(tmpAut) do
imM:=List(a,i->PcElementByExponents(MPcgs,i));
imM:=GroupHomomorphismByImagesNC(Q,Q,Concatenation(MPcgs,gens),Concatenation(imM,gens));
Assert(2,IsBijective(imM));
Add(B,imM);
od;
# test condition for lifting, also add corresponding automorphism
comiso:=GroupHomomorphismByImagesNC(ocr.complement,OQ,gens,List(gens,x->ImagesRepresentative(q,x)));
precond:=fail;
mo:=GModuleByMats(LinearActionLayer(gens,MPcgs),mo.field);
cond:=function(perm)
local aut,newgens,mo2,iso,a; if perm in Aperm then
return true; fi;
aut:=PreImagesRepresentative(AQiso,perm);
newgens:=List(gens,x->PreImagesRepresentative(comiso,
ImagesRepresentative(aut,ImagesRepresentative(comiso,x))));
mo2:=GModuleByMats(LinearActionLayer(newgens,MPcgs),mo.field);
iso:=MTX.IsomorphismModules(mo,mo2); if iso=fail then
return false; else # build associated auto
precond:=function(perm)
local aut,newgens,mo2; if perm in Aperm then
return true; fi;
aut:=PreImagesRepresentative(AQiso,perm);
newgens:=List(GeneratorsOfGroup(Q),
x->PreImagesRepresentative(q,Image(aut,ImagesRepresentative(q,x))));
mo2:=GModuleByMats(LinearActionLayer(newgens,MPcgs),mo.field);
return MTX.IsomorphismModules(mo,mo2)<>fail; end;
cond:=function(perm)
local aut,newgens,mo2,iso,a; if perm in Aperm then
return true; fi;
aut:=PreImagesRepresentative(AQiso,perm);
newgens:=List(GeneratorsOfGroup(Q),
x->PreImagesRepresentative(q,Image(aut,ImagesRepresentative(q,x))));
mo2:=GModuleByMats(LinearActionLayer(newgens,MPcgs),mo.field);
iso:=MTX.IsomorphismModules(mo,mo2); if iso=fail then
return false; else # build associated auto
a:=AGSRAutomLift(ocr,q,aut,iso); if a=fail then #Print("test failed\n");
return false; else
Add(A,a);
Add(Apa,perm);
Aperm:=ClosureGroup(Aperm,perm); #Print("test succeeded\n");
return true; fi; fi; end;
fi;
# find A using the set condition
A:=[];
Apa:=[]; # note: we do not include AQI here, so might need to add later
Aperm:=SubgroupNC(AQP,List(GeneratorsOfGroup(AQI),
x->ImagesRepresentative(AQiso,x)));
# try to find some further generators if Size(AQP)/Size(Aperm)>100then for j in SpecialPcgs(SolvableRadical(AQP)) do
cond(j);
od; for j in GeneratorsOfGroup(AQP) do
cond(j);
od; fi;
sub:=AQP; if precond<>fail and not ForAll(GeneratorsOfGroup(sub),precond) then # compatible pairs condition
sub:=SubgroupProperty(sub,precond,Aperm); fi;
if IndexNC(sub,Aperm)>10^6then # try to find characteristic subgroups
Info(InfoMorph,2,"Use normal subgroup classes"); if nosucl=fail then nosucl:=AGSRNormalSubgroupClasses(G);fi;
nosuf:=List(nosucl,x->Set(List(x,y->Image(lhom,y))));
nosuf:=Filtered(nosuf,x->Size(x[1])>1 and Size(x[1])<Size(OQ));
SortBy(nosuf,Length); for j in nosuf do # stabilize class
k:=SmallGeneratingSet(sub);
ac:=OrbitStabilizerAlgorithm(sub,false,false,
k,List(k,x->PreImagesRepresentative(AQiso,x)),
rec(pnt:=j,
act:= function(set,phi) #local phi; #phi:=PreImagesRepresentative(AQiso,perm);
return Set(List(set,x->Image(phi,x))); end,
onlystab:=true));
Info(InfoMorph,3,"Improved index ",IndexNC(sub,ac.stabilizer)); if Size(ac.stabilizer)<Size(sub) then
sub:=ac.stabilizer; fi;
od; fi;
# Note: Aperm is larger than what is generated by Apa
j:=1; while Size(Aperm)<Size(sub) do
ac:=InnerAutomorphism(OQ,Image(q,GeneratorsOfGroup(Q)[j]));
k:=ImagesRepresentative(AQiso,ac); if not k in Aperm then
Add(Apa,k);
Aperm:=ClosureGroup(Aperm,k);
Add(A,InnerAutomorphism(Q,GeneratorsOfGroup(Q)[j])); fi;
j:=j+1;
od;
# remove redundant generators. Note that Aperm could be to big, thus # make group from Apa
ac:=AGSRReducedGens(SubgroupNC(Parent(sub),Apa),Apa,A); if ac<>fail then
Apa:=GeneratorsOfGroup(ac[1]);
A:=GeneratorsOfGroup(ac[2]); fi;
Info(InfoMorph,2,"Lift Index ",Size(AQP)/Size(sub));
# now make the new automorphism group
innB:=List(SmallGeneratingSet(Q),x->InnerAutomorphism(Q,x));
gens:=ShallowCopy(innB);
Info(InfoMorph,2,"|gens|=",Length(gens),"+",Length(C), "+",Length(B),"+",Length(A));
Append(gens,C);
Append(gens,B);
Append(gens,A);
Assert(2,ForAll(gens,IsBijective)); for j in gens do
SetIsBijective(j,true);
od;
A:=Group(gens);
SetIsAutomorphismGroup(A,true);
SetIsGroupOfAutomorphismsFiniteGroup(A,true);
SetIsFinite(A,true);
AQI:=SubgroupNC(A,innB);
SetInnerAutomorphismsAutomorphismGroup(A,AQI);
AQ:=A; if Size(KernelOfMultiplicativeGeneralMapping(hom))>1
or ValueOption("delaypermrep")<>true then
makeaqiso(); if not IsIdenticalObj(A,AQ) then
A:=AQ; fi; else
A!.makeaqiso:=makeaqiso; fi;
# do we use induced radical automorphisms to help next step? if Size(KernelOfMultiplicativeGeneralMapping(hom))>1 and
Size(A)>10^8 #( ## potentially large GL #Size(GL(Length(MPcgs),RelativeOrders(MPcgs)[1]))>10^10 and ## automorphism size really grew from B/C-bit ##Size(A)/Size(AQP)*Index(AQP,sub)>10^10) ) ## do so for all factors
and ForAll([2..Length(rlgf)],x->rlgf[x]-rlgf[x-1]<10)
and ValueOption("noradicalaut")<>true then
if rada=fail then if IsElementaryAbelian(r) and Size(r)>1then
B:=Pcgs(r);
rf:=GF(RelativeOrders(B)[1]);
ind:=Filtered(ser,x->IsSubset(r,x) and Size(x)>1 and Size(x)<Size(r));
ind:=List(ind,x->List(GeneratorsOfGroup(x),y->ExponentsOfPcElement(B,y)));
ind:=List(ind,x->x*One(rf));
ind:=SpaceAndOrbitStabilizer(Length(B),rf,ind,[]);
rada:=List(GeneratorsOfGroup(ind),x->
GroupHomomorphismByImagesNC(r,r,B,List(x,y->PcElementByExponents(B,List(y,Int)))));
rada:=Group(rada);
SetIsGroupOfAutomorphismsFiniteGroup(rada,true);
NiceMonomorphism(rada:autactbase:=fail,someCharacteristics:=fail); else
ind:=IsomorphismPcGroup(r);
rada:=AutomorphismGroup(Image(ind,r):someCharacteristics:=fail,autactbase:=fail); # we only consider those homomorphism that stabilize the series we use for k in List(ser,x->Image(ind,x)) do if ForAny(GeneratorsOfGroup(rada),x->Image(x,k)<>k) then
Info(InfoMorph,3,"radical automorphism stabilizer");
NiceMonomorphism(rada:autactbase:=fail,someCharacteristics:=fail);
SetIsGroupOfAutomorphismsFiniteGroup(rada,true);
rada:=Stabilizer(rada,k,asAutom); fi;
od; # move back to bad degree
rada:=Group(List(GeneratorsOfGroup(rada),
x-> InducedAutomorphism(InverseGeneralMapping(ind),x))); fi; fi;
rf:=Image(hom,r);
Info(InfoMorph,2,"Use radical automorphisms for reduction");
ind:=[]; for j in GeneratorsOfGroup(rada) do
k:=GroupHomomorphismByImagesNC(rf,rf,
GeneratorsOfGroup(rf),
List(GeneratorsOfGroup(rf),
y->ImagesRepresentative(hom,ImagesRepresentative(j,
PreImagesRepresentative(hom,y)))));
Assert(2,IsBijective(k));
Add(ind,k);
od;
C:=Group(Unique(Concatenation(res,ind))); # to guarantee common parent
SetIsFinite(C,true);
SetIsGroupOfAutomorphismsFiniteGroup(C,true);
Size(C:autactbase:=fail,someCharacteristics:=fail); # disable autactbase transfer
res:=SubgroupNC(C,res);
ind:=SubgroupNC(C,ind); # this should now go via the niceo of C
Size(ind:autactbase:=fail,someCharacteristics:=fail);
Size(res:autactbase:=fail,someCharacteristics:=fail);
ind:=Intersection(res,ind); # only those we care about
if Size(ind)<Size(res) then # reduce to subgroup that induces valid automorphisms
Info(InfoMorph,1,"Radical autos reduce by factor ",Size(res)/Size(ind));
resperm:=IsomorphismPermGroup(C);
proj:=GroupHomomorphismByImagesNC(AQP,Image(resperm),
B[2],List(GeneratorsOfGroup(res),x->ImagesRepresentative(resperm,x)));
C:=PreImage(proj,Image(resperm,ind));
C:=List(SmallGeneratingSet(C),x->PreImagesRepresentative(AQiso,x));
AQ:=Group(C);
SetIsFinite(AQ,true);
SetIsGroupOfAutomorphismsFiniteGroup(AQ,true);
makeaqiso(); fi;
# # hook for using existing characteristics to reduce for next step if somechar<>fail then
u:=Filtered(Unique(List(somechar,x->Image(hom,x))),x->Size(x)>1);
u:=Filtered(u,s->ForAny(GeneratorsOfGroup(AQ),h->Image(h,s)<>s));
SortBy(u,Size);
Info(InfoMorph,1,"Forced characteristics ",List(u,Size));
if scharorb<>fail then # these are subgroups for which certain orbits must be stabilized.
C:=List(Reversed(scharorb),x->List(x,y->Image(hom,y)));
C:=Filtered(C,x->Size(x[1])>1 and Size(x[1])<Size(Q));
Info(InfoMorph,1,"Forced orbits ",List(C,x->Size(x[1])));
Append(u,C); fi;
if Length(u)>0then
C:=MappingGeneratorsImages(AQiso); if C[2]<>GeneratorsOfGroup(AQP) then
C:=[List(GeneratorsOfGroup(AQP),
x->PreImagesRepresentative(AQiso,x)),
GeneratorsOfGroup(AQP)]; fi; for j in u do if IsList(j) then # stabilizer set of subgroups
jorb:=ShallowCopy(Orbit(AQP,j[1],C[2],C[1],asAutom));
jorpo:=[Position(jorb,j[1]),Position(jorb,j[2])]; if jorpo[2]=fail then
Append(jorb,Orbit(AQP,j[1],C[2],C[1],asAutom));
jorpo[2]:=Position(jorb,j[2]); fi; if Length(jorb)>Length(j) then
B:=ActionHomomorphism(AQP,jorb,C[2],C[1],asAutom);
substb:=Group(List(C[2],x->ImagesRepresentative(B,x)),());
substb:=Stabilizer(substb,Set(jorpo),OnSets);
substb:=PreImage(B,substb);
Info(InfoMorph,2,"Stabilize characteristic orbit ",Size(j[1]), " :",Size(AQP)/Size(substb) ); else
substb:=AQP; fi;
else
substb:=Stabilizer(AQP,j,C[2],C[1],asAutom);
Info(InfoMorph,2,"Stabilize characteristic subgroup ",Size(j), " :",Size(AQP)/Size(substb) ); fi; if Size(substb)<Size(AQP) then
B:=Size(substb);
substb:=SmallGeneratingSet(substb);
AQP:=Group(substb);
SetSize(AQP,B);
C:=[List(substb,x->PreImagesRepresentative(AQiso,x)),substb]; fi;
od;
AQ:=Group(C[1]);
SetIsFinite(AQ,true);
SetIsGroupOfAutomorphismsFiniteGroup(AQ,true);
SetSize(AQ,Size(AQP)); #AQP:=Group(C[2]); # ensure small gen set #SetSize(AQP,Size(AQ));
makeaqiso(); fi; fi;
lastperm:=AQiso; else
lastperm:=fail; fi;
i:=i+1;
od;
return AQ;
end);
# find characteristic subgroups by splitting into elementary abelian, # homogeneous layers
BindGlobal("AGSRModuleLayerSeries",function(g)
local s,l,r,i,j,sy,hom,p,pcgs;
s:=ShallowCopy(DerivedSeriesOfGroup(g));
r:=SolvableRadical(Last(s)); if Size(r)>1then# cannot be last, as solvable
Append(s,DerivedSeriesOfGroup(r)); fi;
i:=2; while i<=Length(s) do if HasAbelianFactorGroup(s[i-1],s[i]) then
p:=Factors(IndexNC(s[i-1],s[i]))[1]; # is it a single prime? if not IsPrimePowerInt(IndexNC(s[i-1],s[i])) then
hom:=NaturalHomomorphismByNormalSubgroupNC(s[i-1],s[i]);
sy:=SylowSystem(Image(hom));
l:=[sy[1]]; for j in [2..Length(sy)-1] do
Add(l,ClosureGroup(Last(l),sy[j]));
od;
l:=Reversed(l);
l:=List(l,x->PreImage(hom,x));
Info(InfoMorph,6,"insert prime @",i);
s:=Concatenation(s{[1..i-1]},l,s{[i..Length(s)]}); elif not HasElementaryAbelianFactorGroup(s[i-1],s[i]) then # not elementary abelian -- pth powers suffice as abelian
l:=s[i]; for j in GeneratorsOfGroup(s[i-1]) do
l:=ClosureGroup(l,j^p);
od;
Info(InfoMorph,6,"insert ppower @",i);
s:=Concatenation(s{[1..i-1]},[l],s{[i..Length(s)]}); else # make module
pcgs:=ModuloPcgs(s[i-1],s[i]);
l:=LinearActionLayer(g,pcgs);
l:=GModuleByMats(l,GF(p)); # check for characteristic submodules
r:=MTX.BasisRadical(l); if Length(r)=0then
r:=MTX.BasisSocle(l); if Length(r)=l.dimension then # semisimple -- use homogeneous
sy:=List(MTX.CollectedFactors(l),x->x[1]); if Length(sy)>1then
r:=Minimum(List(sy,x->x.dimension));
sy:=Filtered(sy,x->x.dimension=r);
r:=[]; for j in sy do
Append(r,MTX.Homomorphisms(j,l));
od;
r:=Concatenation(r);
r:=Filtered(TriangulizedMat(r),x->not IsZero(x)); else
r:=fail; fi; fi; fi;
if r=fail then
i:=i+1; else
l:=s[i]; for j in r do;
l:=ClosureGroup(l,PcElementByExponents(pcgs,j));
od; if Size(l)<Size(s[i-1]) and Size(l)>Size(s[i]) then
Info(InfoMorph,6,"insert module @",i);
s:=Concatenation(s{[1..i-1]},[l],s{[i..Length(s)]}); else
i:=i+1; fi; fi; fi; else
i:=i+1; fi;
od;
return s; end);
# find corresponding characteristic subgroups
BindGlobal("AGSRMatchedCharacteristics",function(g,h)
local a,props,cg,ch,clg,clh,ng,nh,coug,couh,pg,ph,i,j,stop,coinc;
props:=function(a)
local p,b;
if ID_AVAILABLE(Size(a))<>fail then
p:=ShallowCopy(-IdGroup(a)); # negative avoids clash with others else
p:=[Size(a)];
b:=ShallowCopy(AbelianInvariants(a));
Sort(b);
Add(p,b);
Add(p,List(DerivedSeriesOfGroup(a),Size)); fi; # # intersections # for i in [1..Length(chars)] do # for j in AGSRModuleLayerSeries(chars[i]) do # der(Intersection(j,a)); # der(ClosureGroup(j,a)); # od; # od;
return p; end;
# Process that G-subgroup i matches H-subgroup j. Return true if there is # a problem.
coinc:=function(i,j)
local a,b,sa,sb,sel,p,q; if pg[i]<>ph[j] then Error("matching bug");fi;
a:=cg[i];
b:=ch[j];
Add(ng,a);
Add(nh,b);
sel:=Difference([1..Length(cg)],[i]);
cg:=cg{sel};
pg:=pg{sel};
sel:=Difference([1..Length(ch)],[j]);
ch:=ch{sel};
ph:=ph{sel}; # find associated modules and further match
sa:=AGSRModuleLayerSeries(a);
sb:=AGSRModuleLayerSeries(b); if List(sa,Size)<>List(sb,Size) then return true;fi; for i in [1..Length(sa)] do
p:=Position(cg,sa[i]);
q:=Position(ch,sb[i]); if p=fail then if q<>fail then return true;fi; elif q=fail then return true; else if pg[p]<>ph[q] # but not same properties
or coinc(p,q) then return true;fi; fi;
od;
return false; end;
ng:=[];
nh:=[];
# get the characteristic subgroups
cg:=ShallowCopy(CharacteristicSubgroups(g));
ch:=ShallowCopy(CharacteristicSubgroups(h));
SortBy(cg,x->-Size(x));
SortBy(ch,x->-Size(x));
# find list of properties, tryign to match them up
pg:=List(cg,props);
ph:=List(ch,props);
stop:=false; while Length(cg)>0 and not stop do # test in loop as list changes if Collected(pg)<>Collected(ph) then return fail;fi;
i:=First([1..Length(pg)],x->Number(pg,y->y=pg[x])=1); if i<>fail then # found a unique one -- process # because properties agree this must match
j:=Position(ph,pg[i]); if coinc(i,j) then return fail;fi; else
stop:=true; # give up, for the moment # try clusters
j:=Set(pg);
clg:=List(j,x->cg{Filtered([1..Length(cg)],y->pg[y]=x)});
clh:=List(j,x->ch{Filtered([1..Length(ch)],y->ph[y]=x)}); # also use classes of size 1 for compare
Append(clg,List(ng,x->[x]));
Append(clh,List(nh,x->[x])); # sort larger first
SortParallel(clg,clh,function(a,b) return Size(a[1])>Size(b[1]);end);
i:=1; while i<=Length(clg) do if Length(clg[i])>1then
j:=i+1; while j<=Length(clg) do
coug:=List(clg[i],x->Number(clg[j],y->IsSubset(x,y)));
couh:=List(clh[i],x->Number(clh[j],y->IsSubset(x,y))); if Collected(coug)<>Collected(couh) then return fail;fi;
a:=First(Collected(coug),x->x[2]=1); if a<>fail then # unique number -- split
a:=a[1]; if coinc(Position(cg,clg[i][Position(coug,a)]),
Position(ch,clh[i][Position(couh,a)])) then return fail;fi;
i:=Length(clg); j:=Length(clg); # break out of loops
stop:=false; fi;
j:=j+java.lang.StringIndexOutOfBoundsException: Index 6 out of bounds for length 6
od; fi;
ii;
od fi;
od;
=
local orb,rep,S,i,g,img,p;
orb:=[from];
rep:=[One(G)];
S=;
: while<java.lang.StringIndexOutOfBoundsException: Range [27, 28) out of bounds for length 27 for g
img:=act(orb[i],g);
p:=Position(orb,img); if p=fail then if Length(orb)>=bound then return fail;fi; # length bailout
Add(orb,img);
Add(rep,rep[i]*g); else
img:=rep[i]*g/rep[p]; if not (img in S or img^-1 in S) Info(InfoMorph,1,"Shortorb factorInfoMorph," java.lang.StringIndexOutOfBoundsException: Range [51, 50) out of bounds for length 65
Add(S,img); fi; fi;
od;
i:=i+1;
od;
p:=Position(orb,to); if p=fail then return false;fi; # not in orbit
return rec(rep:=rep[p],orblen:=Length(orb),Sjava.lang.StringIndexOutOfBoundsException: Range [37, 36) out of bounds for length 42 endmapfail
# pathetic isomorphism test, based on the automorphism group of GxH. This is # only of use as long as we don't yet have a Cannon/Holt version of # isomorphism available and there are many generators
InstallGlobalFunction(Info(,,Factor")Size)",
local d,a,map,cG,nG" by,api/u)
:u
# TODO: use matgrp package if not (IsPermGroup(G) or IsPcGroup(G)) then
i:=IsomorphismPermGroup(G);
iso:=PatheticIsomorphism(Image(i,G),H); if iso=fail then
return iso; else
return i*iso; fi; fi
# TODO: use matgrp package if not (IsPermGroup(H) or IsPcGroup(H)) then
i:=IsomorphismPermGroup(H);
iso:=PatheticIsomorphism(G,Image(i,H)); if iso=fail then
return iso; else
return iso*InverseGeneralMapping(i); fi; fi;
# go through factors of characteristic series to keep orbits short.
AutomorphismGroup(G:someCharacteristics:=fail);
AutomorphismGroup(H:someCharacteristics:=fail);
d:=AGSRMatchedCharacteristics(G,H); if d=fail then return fail;fi; # characteristics do not match
nG:=d.ng;
nH:=d.nh; for i in [1..Length(d.cg)] do
u:=TrivialSubgroup(G); for j in d.cg[i] do
u:=ClosureGroup(u,j);
od; if not u in nG then
Add(nG,u);
u:=TrivialSubgroup(H); for j in d.ch[i] do
u:=ClosureGroup(u,j);
od;
Add(nH,u); fi;
od;
d:=DirectProduct(G,H);
e1:=Embedding(d,1);
e2:=Embedding(d,2); # combine images of characteristic factors, reverse order
cG:=[];
nG:=Reversed(nG);
nH:=Reversed(nH); for i in [1..Length(nG)] do
Add(cG,ClosureGroup(Image(e1,nG[i]),Image(e2,nH[i])));
od;
nG:=Concatenation([TrivialSubgroup(G)],nG);
nH:=Concatenation([TrivialSubgroup(H)],nH);
SortParallel(nG,nH,function(a,b) return Size(a)<Size(b);end); if List(nG,Size)<>List(nH,Size) then return fail;fi;
for i in [2..Length(nG)] do
K:=Filtered([1..Length(nG)],x->Size(nG[x])*2=Size(nG[i])
and IsSubset(nG[i],nG[x])); if Length(K)>0then
K:=K[1]; # We are seeking an isomorphism, not the full automorphism group of # GxG. It is thus sufficient, if we find the subgroup Aut(G)\wr 2.
# We now found that G and H have two characteristic subgroups A<B with # [B:A]=2. An isomorphism swapping G and H will need to map B to B and # A to A. Furthermore, in the factor modulo A_G xA_H, a generator of # B_G must be swappes with a generator of B_H. # This implies that A_G\times A_H, together with the diagonal of B is # characteristic in Aut(A)\wr 2. We thus may add this subgroup as # ``characteristic'' to improve the series.
Add(cG,ClosureGroup(
ClosureGroup(Image(e1,nG[K]),Image(e2,nH[K])),
Image(e1,First(GeneratorsOfGroup(nG[i]),x->not x in nG[K]))
*Image(e2,First(GeneratorsOfGroup(nH[i]),x->not x in nH[K]))));
fi;
od;
aab:=[Image(e1,G),Image(e2,H)]; # we also fix the *pairs* of the characteristic subgroups as orbits. Again # this must happen in Aut(G)\wr 2, and reduces the size of the group.
somechar:=rec(subgroups:=cG,
orbits:=List([1..Length(nG)],x->[Image(e1,nG[x]),Image(e2,nH[x])]));
a:=AutomorphismGroup(d:autactbase:=aab,someCharacteristics:=somechar,
directs:=aab,
delaypermrep:=true ); for i in cG do if not ForAll(GeneratorsOfGroup(a),x->Image(x,i)=i) then
a:=Stabilizer(a,i,asAutomorphism); fi;
od;
# now work in reverse through the characteristic factors
conj:=One(a);
K:=Image(e1,G);
L:=Image(e2,H);
map:=AGBoundedOrbrep(a,K,L,asAutomorphism,20); if map=false then
Info(InfoMorph,1,"Shortorb test noniso");
return fail; elif map<>fail then
conj:=map.rep;
Info(InfoMorph,1,"Shortorb test iso found"); else
as:=a;
Add(cG,TrivialSubgroup(d));
SortBy(cG,x->-Size(x)); for i in cG do
u:=ClosureGroup(i,K);
v:=ClosureGroup(i,L); if u<>v then
# try cheap orbit stabilizer first if iso<>fail then
map:=fail; else
map:=AGBoundedOrbrep(as,u,v,asAutomorphism,100); fi; if map=false then
Info(InfoMorph,1,"Shortorb factor noniso");
return fail; elif map<>fail then
Info(InfoMorph,1,"Shortorb factor reduce ",map.orblen);
as:=SubgroupNC(Parent(as),map.stabgens);
map:=map.rep;
conj:=conj*map;
K:=Image(map,K);
as:=as^map; else if iso=fail then
Info(InfoMorph,1,"Shortorb failed, get delayed permrep"); if IsBound(a!.makeaqiso) then a!.makeaqiso();fi;
iso:=IsomorphismPermGroup(a:autactbase:=aab);
api:=Image(iso,as); fi;
if IsSolvableGroup(api) then
gens:=Pcgs(api); else
gens:=SmallGeneratingSet(api); fi;
pre:=List(gens,x->PreImagesRepresentative(iso,x));
map:=RepresentativeAction(SubgroupNC(a,pre),u,v,asAutomorphism); if map=fail then
return fail; fi;
conj:=conj*map;
K:=Image(map,K);
if Size(i)>1then
u:=Stabilizer(api,v,gens,pre,asAutomorphism);
Info(InfoMorph,1,"Factor ",Size(d)/Size(i),": ", "reduce by ",Size(api)/Size(u));
api:=u; fi; fi; fi;
od;
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