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############################################################################# ## #W twocohom.gd GAP library Bettina Eick ## #Y Copyright (C) 1997, Lehrstuhl D für Mathematik, RWTH Aachen, Germany #Y (C) 1998 School Math and Comp. Sci., University of St Andrews, Scotland #Y Copyright (C) 2002 The GAP Group ## ############################################################################# ## #F CollectedWordSQ( <C>, <u>, <v> ) ## ## <ManSection> ## <Func Name="CollectedWordSQ" Arg='C, u, v'/> ## ## <Description> ## </Description> ## </ManSection> ## DeclareGlobalFunction( "CollectedWordSQ" ); ############################################################################# ## #F CollectorSQ( <G>, <M>, <isSplit> ) ## ## <ManSection> ## <Func Name="CollectorSQ" Arg='G, M, isSplit'/> ## ## <Description> ## </Description> ## </ManSection> ## DeclareGlobalFunction( "CollectorSQ" ); ############################################################################# ## #F AddEquationsSQ( <eq>, <t1>, <t2> ) ## ## <ManSection> ## <Func Name="AddEquationsSQ" Arg='eq, t1, t2'/> ## ## <Description> ## </Description> ## </ManSection> ## DeclareGlobalFunction( "AddEquationsSQ" ); ############################################################################# ## #F SolutionSQ( <C>, <eq> ) ## ## <ManSection> ## <Func Name="SolutionSQ" Arg='C, eq'/> ## ## <Description> ## </Description> ## </ManSection> ## DeclareGlobalFunction( "SolutionSQ" ); ############################################################################# ## #F TwoCocyclesSQ( <C>, <G>, <M> ) ## ## <ManSection> ## <Func Name="TwoCocyclesSQ" Arg='C, G, M'/> ## ## <Description> ## </Description> ## </ManSection> ## DeclareGlobalFunction( "TwoCocyclesSQ" ); ############################################################################# ## #F TwoCoboundariesSQ( <C>, <G>, <M> ) ## ## <ManSection> ## <Func Name="TwoCoboundariesSQ" Arg='C, G, M'/> ## ## <Description> ## </Description> ## </ManSection> ## DeclareGlobalFunction( "TwoCoboundariesSQ" ); ############################################################################# ## #F TwoCohomologySQ( <C>, <G>, <M> ) ## ## <ManSection> ## <Func Name="TwoCohomologySQ" Arg='C, G, M'/> ## ## <Description> ## </Description> ## </ManSection> ## DeclareGlobalFunction( "TwoCohomologySQ" ); ############################################################################# ## #O TwoCocycles( <G>, <M> ) ## ## <#GAPDoc Label="TwoCocycles"> ## <ManSection> ## <Oper Name="TwoCocycles" Arg='G, M'/> ## ## <Description> ## returns the <M>2</M>-cocycles of a pc group <A>G</A> by the ## <A>G</A>-module <A>M</A>. ## The generators of <A>M</A> must correspond to the <Ref Func="Pcgs"/> ## value of <A>G</A>. The operation ## returns a list of vectors over the field underlying <A>M</A> and the ## additive group generated by these vectors is the group of ## <M>2</M>-cocyles. ## </Description> ## </ManSection> ## <#/GAPDoc> ## DeclareOperation( "TwoCocycles", [ IsPcGroup, IsObject ] ); ############################################################################# ## #O TwoCoboundaries( <G>, <M> ) ## ## <#GAPDoc Label="TwoCoboundaries"> ## <ManSection> ## <Oper Name="TwoCoboundaries" Arg='G, M'/> ## ## <Description> ## returns the group of <M>2</M>-coboundaries of a pc group <A>G</A> by the ## <A>G</A>-module <A>M</A>. ## The generators of <A>M</A> must correspond to the <Ref Func="Pcgs"/> ## value of <A>G</A>. ## The group of coboundaries is given as vector space over the field ## underlying <A>M</A>. ## </Description> ## </ManSection> ## <#/GAPDoc> ## DeclareOperation( "TwoCoboundaries", [ IsPcGroup, IsObject ] ); ############################################################################# ## #O TwoCohomology( <G>, <M> ) ## ## <#GAPDoc Label="TwoCohomology"> ## <ManSection> ## <Oper Name="TwoCohomology" Arg='G, M'/> ## ## <Description> ## returns a record defining the second cohomology group as factor space of ## the space of cocycles by the space of coboundaries. ## <A>G</A> must be a pc group and the generators of <A>M</A> must ## correspond to the pcgs of <A>G</A>. ## <Example><![CDATA[ ## gap> G := SmallGroup( 4, 2 ); ## <pc group of size 4 with 2 generators> ## gap> mats := List( Pcgs( G ), x -> IdentityMat( 1, GF(2) ) ); ## [ [ <a GF2 vector of length 1> ], [ <a GF2 vector of length 1> ] ] ## gap> M := GModuleByMats( mats, GF(2) ); ## rec( IsOverFiniteField := true, dimension := 1, field := GF(2), ## generators := [ <an immutable 1x1 matrix over GF2>, ## <an immutable 1x1 matrix over GF2> ], isMTXModule := true ) ## gap> TwoCoboundaries( G, M ); ## [ ] ## gap> TwoCocycles( G, M ); ## [ [ Z(2)^0, 0*Z(2), 0*Z(2) ], [ 0*Z(2), Z(2)^0, 0*Z(2) ], ## [ 0*Z(2), 0*Z(2), Z(2)^0 ] ] ## gap> cc := TwoCohomology( G, M );; ## gap> cc.cohom; ## <linear mapping by matrix, <vector space of dimension 3 over GF( ## 2)> -> ( GF(2)^3 )> ## ]]></Example> ## </Description> ## </ManSection> ## <#/GAPDoc> ## DeclareOperation( "TwoCohomology", [ IsPcGroup, IsObject ] ); ############################################################################# ## #E