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#############################################################################
##
## This file is part of GAP, a system for computational discrete algebra.
## This file's authors include Frank Celler.
##
## 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 the operations for the construction of the classical
## group types.
##
#############################################################################
##
## <#GAPDoc Label="[1]{classic}">
## The following functions return classical groups.
## <P/>
## For the linear, symplectic, and unitary groups (the latter in dimension
## at least <M>3</M>),
## the generators are taken from <Cite Key="Tay87"/>.
## For the unitary groups in dimension <M>2</M>, the isomorphism of
## SU<M>(2,q)</M> and SL<M>(2,q)</M> is used,
## see for example <Cite Key="Hup67"/>.
## <P/>
## The generators of the general and special orthogonal groups are taken
## from <Cite Key="IshibashiEarnest94"/> and
## <Cite Key="KleidmanLiebeck90"/>,
## except that the generators of the groups in odd dimension in even
## characteristic are constructed via the isomorphism to a symplectic group,
## see for example <Cite Key="Car72a"/>.
## <P/>
## The generators of the groups <M>\Omega^\epsilon(d, q)</M> are taken
## from <Cite Key="RylandsTalor98"/>,
## except that in odd dimension and even characteristic,
## the generators of SO<M>(d, q)</M> are taken for <M>\Omega(d, q)</M>.
## Note that the generators claimed
## in <Cite Key="RylandsTalor98" Where="Section 4.5 and 4.6"/>
## do not describe orthogonal groups, one would have to transpose these
## matrices in order to get groups that respect the required forms.
## The matrices from <Cite Key="RylandsTalor98"/> generate groups
## of the right isomorphism types but not orthogonal groups,
## except in the case <M>(d,q) = (5,2)</M>,
## where the matrices from <Cite Key="RylandsTalor98"/> generate
## the simple group <M>S_4(2)'</M> and not the group <M>S_4(2)</M>.
## <P/>
## The generators for the semilinear groups are constructed from the
## generators of the corresponding linear groups plus one additional
## generator that describes the action of the group of field automorphisms;
## for prime integers <M>p</M> and positive integers <M>f</M>,
## this yields the matrix groups <M>Gamma</M>L<M>(d, p^f)</M> and
## <M>Sigma</M>L<M>(d, p^f)</M> as groups of <M>d f \times df</M> matrices
## over the field with <M>p</M> elements.
## <P/>
## For symplectic and orthogonal matrix groups returned by the functions
## described below, the invariant bilinear form is stored as the value of
## the attribute <Ref Attr="InvariantBilinearForm"/>.
## Analogously, the invariant sesquilinear form defining the unitary groups
## is stored as the value of the attribute
## <Ref Attr="InvariantSesquilinearForm"/>).
## The defining quadratic form of orthogonal groups is stored as the value
## of the attribute <Ref Attr="InvariantQuadraticForm"/>.
## <P/>
## Note that due to the different sources for the generators,
## the invariant forms for the groups <M>\Omega(e,d,q)</M> are in general
## different from the forms for SO<M>(e,d,q)</M> and GO<M>(e,d,q)</M>.
## If version at least 1.2.6 of the <Package>Forms</Package> package is
## loaded then compatible groups can be created by specifying the desired
## form, see the sections below.
## <#/GAPDoc>
##
#############################################################################
##
#O GeneralLinearGroupCons( <filter>, <d>, <R> )
##
## <ManSection>
## <Oper Name="GeneralLinearGroupCons" Arg='filter, d, R'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "GeneralLinearGroupCons", [ IsGroup, IsPosInt, IsRing ] );
#############################################################################
##
#F GeneralLinearGroup( [<filt>, ]<d>, <R> ) . . . . . general linear group
#F GL( [<filt>, ]<d>, <R> )
#F GeneralLinearGroup( [<filt>, ]<d>, <q> )
#F GL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="GeneralLinearGroup">
## <ManSection>
## <Heading>GeneralLinearGroup</Heading>
## <Func Name="GeneralLinearGroup" Arg='[filt, ]d, R'
## Label="for dimension and a ring"/>
## <Func Name="GL" Arg='[filt, ]d, R'
## Label="for dimension and a ring"/>
## <Func Name="GeneralLinearGroup" Arg='[filt, ]d, q'
## Label="for dimension and field size"/>
## <Func Name="GL" Arg='[filt, ]d, q'
## Label="for dimension and field size"/>
##
## <Description>
## The first two forms construct a group isomorphic to the general linear
## group GL( <A>d</A>, <A>R</A> ) of all <M><A>d</A> \times <A>d</A></M>
## matrices that are invertible over the ring <A>R</A>,
## in the category given by the filter <A>filt</A>.
## <P/>
## The third and the fourth form construct the general linear group over the
## finite field with <A>q</A> elements.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the general linear group as a matrix group in
## its natural action (see also <Ref Prop="IsNaturalGL"/>,
## <Ref Prop="IsNaturalGLnZ"/>).
## <P/>
## Currently supported rings <A>R</A> are finite fields,
## the ring <Ref Var="Integers" Label="global variable"/>,
## and residue class rings <C>Integers mod <A>m</A></C>,
## see <Ref Sect="Residue Class Rings"/>.
## <P/>
## <Example><![CDATA[
## gap> GL(4,3);
## GL(4,3)
## gap> GL(2,Integers);
## GL(2,Integers)
## gap> GL(3,Integers mod 12);
## GL(3,Z/12Z)
## ]]></Example>
## <P/>
## <Index Key="OnLines" Subkey="example"><C>OnLines</C></Index>
## Using the <Ref Func="OnLines"/> operation it is possible to obtain the
## corresponding projective groups in a permutation action:
## <P/>
## <Example><![CDATA[
## gap> g:=GL(4,3);;Size(g);
## 24261120
## gap> pgl:=Action(g,Orbit(g,Z(3)^0*[1,0,0,0],OnLines),OnLines);;
## gap> Size(pgl);
## 12130560
## ]]></Example>
## <P/>
## If you are interested only in the projective group as a permutation group
## and not in the correspondence between its moved points and the points in
## the projective space, you can also use <Ref Func="PGL"/>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "GeneralLinearGroup", function ( arg )
if Length( arg ) = 2 then
if IsRing( arg[2] ) then
return GeneralLinearGroupCons( IsMatrixGroup, arg[1], arg[2] );
elif IsPrimePowerInt( arg[2] ) then
return GeneralLinearGroupCons( IsMatrixGroup, arg[1], GF( arg[2] ) );
fi;
elif Length( arg ) = 3 and IsOperation( arg[1] ) then
if IsRing( arg[3] ) then
return GeneralLinearGroupCons( arg[1], arg[2], arg[3] );
elif IsPrimePowerInt( arg[3] ) then
return GeneralLinearGroupCons( arg[1], arg[2], GF( arg[3] ) );
fi;
fi;
Error( "usage: GeneralLinearGroup( [<filter>, ]<d>, <R> )" );
end );
DeclareSynonym( "GL", GeneralLinearGroup );
#############################################################################
##
#O GeneralOrthogonalGroupCons( <filter>, <e>, <d>, <q> )
##
## <ManSection>
## <Oper Name="GeneralOrthogonalGroupCons" Arg='filter, e, d, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "GeneralOrthogonalGroupCons",
[ IsGroup, IsInt, IsPosInt, IsPosInt ] );
DeclareConstructor( "GeneralOrthogonalGroupCons",
[ IsGroup, IsInt, IsPosInt, IsRing ] );
#############################################################################
##
#F GeneralOrthogonalGroup( [<filt>, ][<e>, ]<d>, <q>[, <form>] )
#F GeneralOrthogonalGroup( [<filt>, ]<form> )
#F GO( [<filt>, ][<e>, ]<d>, <q>[, <form>] )
#F GO( [<filt>, ]<form> )
##
## <#GAPDoc Label="GeneralOrthogonalGroup">
## <ManSection>
## <Func Name="GeneralOrthogonalGroup" Arg='[filt, ][e, ]d, q[, form]'/>
## <Func Name="GeneralOrthogonalGroup" Arg='[filt, ]form' Label="for a form"/>
## <Func Name="GO" Arg='[filt, ][e, ]d, q[, form]'/>
## <Func Name="GO" Arg='[filt, ]form' Label="for a form"/>
##
## <Description>
## constructs a group isomorphic to the
## general orthogonal group GO( <A>e</A>, <A>d</A>, <A>q</A> ) of those
## <M><A>d</A> \times <A>d</A></M> matrices over the field with <A>q</A>
## elements that respect a non-singular quadratic form
## (see <Ref Attr="InvariantQuadraticForm"/>) specified by <A>e</A>,
## in the category given by the filter <A>filt</A>.
## <P/>
## The value of <A>e</A> must be <M>0</M> for odd <A>d</A> (and can
## optionally be omitted in this case), respectively one of <M>1</M> or
## <M>-1</M> for even <A>d</A>.
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the general orthogonal group itself.
## <P/>
## If version at least 1.2.6 of the <Package>Forms</Package> package is
## loaded then the desired quadratic form can be specified via <A>form</A>,
## which can be either a matrix
## or a form object in <Ref Filt="IsQuadraticForm" BookName="Forms"/>
## or a group with stored <Ref Attr="InvariantQuadraticForm"/> value
## (and then this form is taken).
## <P/>
## A given <A>form</A> determines <A>e</A> and <A>d</A>, and also <A>q</A>
## except if <A>form</A> is a matrix that does not store its
## <Ref Attr="BaseDomain" Label="for a matrix object"/> value.
## These parameters can be entered, and an error is signalled if they do
## not fit to the given <A>form</A>.
## <P/>
## If <A>form</A> is not given then a default is chosen as described in the
## introduction to Section <Ref Sect="Classical Groups"/>.
## <P/>
## Note that in <Cite Key="KleidmanLiebeck90"/>,
## GO is defined as the stabilizer
## <M>\Delta(V, F, \kappa)</M> of the quadratic form, up to scalars,
## whereas our GO is called <M>I(V, F, \kappa)</M> there.
## <P/>
## <Example><![CDATA[
## gap> GeneralOrthogonalGroup( 5, 3 );
## GO(0,5,3)
## gap> GeneralOrthogonalGroup( -1, 8, 2 );
## GO(-1,8,2)
## gap> GeneralOrthogonalGroup( IsPermGroup, -1, 8, 2 );
## Perm_GO(-1,8,2)
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "DescribesInvariantQuadraticForm",
obj -> IsMatrixOrMatrixObj( obj ) or
( IsBoundGlobal( "IsQuadraticForm" ) and
ValueGlobal( "IsQuadraticForm" )( obj ) ) or
( IsGroup( obj ) and HasInvariantQuadraticForm( obj ) ) );
BindGlobal( "GeneralOrthogonalGroup", function ( arg )
local filt, form;
if IsFilter( First( arg ) ) then
filt:= Remove( arg, 1 );
else
filt:= IsMatrixGroup;
fi;
if DescribesInvariantQuadraticForm( Last( arg ) ) then
form:= Remove( arg );
if Length( arg ) = 0 then
# ( [<filt>, ]<form> )
return GeneralOrthogonalGroupCons( filt, form );
elif Length( arg ) = 2 and IsPosInt( arg[1] )
and ( IsPosInt( arg[2] ) or IsRing( arg[2] ) ) then
# ( [<filt>, ]<d>, <q>, form ) or ( [<filt>, ]<d>, <R>, form )
return GeneralOrthogonalGroupCons( filt, 0, arg[1], arg[2], form );
elif Length( arg ) = 3 and IsInt( arg[1] ) and IsPosInt( arg[2] )
and ( IsPosInt( arg[3] ) or IsRing( arg[3] ) ) then
# ( [<filt>, ]<e>, <d>, <q>, form ) or ( [<filt>, ]<e>, <d>, <R>, form )
return GeneralOrthogonalGroupCons( filt, arg[1], arg[2], arg[3], form );
fi;
elif Length( arg ) = 2 and IsPosInt( arg[1] )
and ( IsPosInt( arg[2] ) or IsRing( arg[2] ) ) then
# ( [<filt>, ]<d>, <q> ) or ( [<filt>, ]<d>, <R> )
return GeneralOrthogonalGroupCons( filt, 0, arg[1], arg[2] );
elif Length( arg ) = 3 and IsInt( arg[1] ) and IsPosInt( arg[2] )
and ( IsPosInt( arg[3] ) or IsRing( arg[3] ) ) then
# ( [<filt>, ]<e>, <d>, <q> ) or ( [<filt>, ]<e>, <d>, <R> )
return GeneralOrthogonalGroupCons( filt, arg[1], arg[2], arg[3] );
fi;
Error( "usage: GeneralOrthogonalGroup( [<filt>, ][<e>, ]<d>, <q>[, <form>] )\n",
"or GeneralOrthogonalGroup( [<filt>, ][<e>, ]<d>, <q>[, <form>] )\n",
"or GeneralOrthogonalGroup( [<filt>, ]<form> )" );
end );
DeclareSynonym( "GO", GeneralOrthogonalGroup );
#############################################################################
##
#O GeneralUnitaryGroupCons( <filter>, <d>, <q> )
##
## <ManSection>
## <Oper Name="GeneralUnitaryGroupCons" Arg='filter, d, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "GeneralUnitaryGroupCons",
[ IsGroup, IsPosInt, IsPosInt ] );
#############################################################################
##
#F GeneralUnitaryGroup( [<filt>, ]<d>, <q>[, <form>] )
#F GeneralUnitaryGroup( [<filt>, ]<form> )
#F GU( [<filt>, ]<d>, <q>[, <form>] )
#F GU( [<filt>, ]<form> )
##
## <#GAPDoc Label="GeneralUnitaryGroup">
## <ManSection>
## <Func Name="GeneralUnitaryGroup" Arg='[filt, ]d, q[, form]'/>
## <Func Name="GeneralUnitaryGroup" Arg='[filt, ]form' Label="for a form"/>
## <Func Name="GU" Arg='[filt, ]d, q[, form]'/>
## <Func Name="GU" Arg='[filt, ]form' Label="for a form"/>
##
## <Description>
## constructs a group isomorphic to the general unitary group
## GU( <A>d</A>, <A>q</A> ) of those <M><A>d</A> \times <A>d</A></M>
## matrices over the field with <M><A>q</A>^2</M> elements
## that respect a fixed nondegenerate sesquilinear form,
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the general unitary group itself.
## <P/>
## If version at least 1.2.6 of the <Package>Forms</Package> package is
## loaded then the desired sesquilinear form can be specified via
## <A>form</A>, which can be either a matrix
## or a form object in <Ref Filt="IsHermitianForm" BookName="Forms"/>
## or a group with stored <Ref Attr="InvariantSesquilinearForm"/> value
## (and then this form is taken).
## <P/>
## A given <A>form</A> determines <A>d</A>, and also <A>q</A>
## except if <A>form</A> is a matrix that does not store its
## <Ref Attr="BaseDomain" Label="for a matrix object"/> value.
## These parameters can be entered, and an error is signalled if they do
## not fit to the given <A>form</A>.
## <P/>
## If <A>form</A> is not given then a default is chosen as described in the
## introduction to Section <Ref Sect="Classical Groups"/>.
## <P/>
## <Example><![CDATA[
## gap> GeneralUnitaryGroup( 3, 5 );
## GU(3,5)
## gap> GeneralUnitaryGroup( IsPermGroup, 3, 5 );
## Perm_GU(3,5)
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "DescribesInvariantHermitianForm",
obj -> IsMatrixOrMatrixObj( obj ) or
( IsBoundGlobal( "IsHermitianForm" ) and
ValueGlobal( "IsHermitianForm" )( obj ) ) or
( IsGroup( obj ) and HasInvariantSesquilinearForm( obj ) ) );
BindGlobal( "GeneralUnitaryGroup", function ( arg )
local filt, form;
if IsFilter( First( arg ) ) then
filt:= Remove( arg, 1 );
else
filt:= IsMatrixGroup;
fi;
if DescribesInvariantHermitianForm( Last( arg ) ) then
form:= Remove( arg );
if Length( arg ) = 0 then
# ( [<filt>, ]<form> )
return GeneralUnitaryGroupCons( filt, form );
elif Length( arg ) = 2 and IsPosInt( arg[1] ) and IsPosInt( arg[2] ) then
# ( [<filt>, ]<d>, <q>, <form> )
return GeneralUnitaryGroupCons( filt, arg[1], arg[2], form );
fi;
elif Length( arg ) = 2 and IsPosInt( arg[1] ) and IsPosInt( arg[2] ) then
# ( [<filt>, ]<d>, <q> )
return GeneralUnitaryGroupCons( filt, arg[1], arg[2] );
fi;
Error( "usage: GeneralUnitaryGroup( [<filt>, ]<d>, <q>[, <form>] )\n",
"or GeneralUnitaryGroup( [<filt>, ]<form> )" );
end );
DeclareSynonym( "GU", GeneralUnitaryGroup );
#############################################################################
##
#O SpecialLinearGroupCons( <filter>, <d>, <R> )
##
## <ManSection>
## <Oper Name="SpecialLinearGroupCons" Arg='filter, d, R'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "SpecialLinearGroupCons", [ IsGroup, IsInt, IsRing ] );
#############################################################################
##
#F SpecialLinearGroup( [<filt>, ]<d>, <R> ) . . . . . special linear group
#F SL( [<filt>, ]<d>, <R> )
#F SpecialLinearGroup( [<filt>, ]<d>, <q> )
#F SL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="SpecialLinearGroup">
## <ManSection>
## <Heading>SpecialLinearGroup</Heading>
## <Func Name="SpecialLinearGroup" Arg='[filt, ]d, R'
## Label="for dimension and a ring"/>
## <Func Name="SL" Arg='[filt, ]d, R'
## Label="for dimension and a ring"/>
## <Func Name="SpecialLinearGroup" Arg='[filt, ]d, q'
## Label="for dimension and a field size"/>
## <Func Name="SL" Arg='[filt, ]d, q'
## Label="for dimension and a field size"/>
##
## <Description>
## The first two forms construct a group isomorphic to the special linear
## group SL( <A>d</A>, <A>R</A> ) of all those
## <M><A>d</A> \times <A>d</A></M> matrices over the ring <A>R</A> whose
## determinant is the identity of <A>R</A>,
## in the category given by the filter <A>filt</A>.
## <P/>
## The third and the fourth form construct the special linear group over the
## finite field with <A>q</A> elements.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the special linear group as a matrix group in
## its natural action (see also <Ref Prop="IsNaturalSL"/>,
## <Ref Prop="IsNaturalSLnZ"/>).
## <P/>
## Currently supported rings <A>R</A> are finite fields,
## the ring <Ref Var="Integers"/>,
## and residue class rings <C>Integers mod <A>m</A></C>,
## see <Ref Sect="Residue Class Rings"/>.
## <P/>
## <Example><![CDATA[
## gap> SpecialLinearGroup(2,2);
## SL(2,2)
## gap> SL(3,Integers);
## SL(3,Integers)
## gap> SL(4,Integers mod 4);
## SL(4,Z/4Z)
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "SpecialLinearGroup", function ( arg )
if Length( arg ) = 2 then
if IsRing( arg[2] ) then
return SpecialLinearGroupCons( IsMatrixGroup, arg[1], arg[2] );
elif IsPrimePowerInt( arg[2] ) then
return SpecialLinearGroupCons( IsMatrixGroup, arg[1], GF( arg[2] ) );
fi;
elif Length( arg ) = 3 and IsOperation( arg[1] ) then
if IsRing( arg[3] ) then
return SpecialLinearGroupCons( arg[1], arg[2], arg[3] );
elif IsPrimePowerInt( arg[3] ) then
return SpecialLinearGroupCons( arg[1], arg[2], GF( arg[3] ) );
fi;
fi;
Error( "usage: SpecialLinearGroup( [<filter>, ]<d>, <R> )" );
end );
DeclareSynonym( "SL", SpecialLinearGroup );
#############################################################################
##
#O SpecialOrthogonalGroupCons( <filter>, <e>, <d>, <q> )
##
## <ManSection>
## <Oper Name="SpecialOrthogonalGroupCons" Arg='filter, e, d, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "SpecialOrthogonalGroupCons",
[ IsGroup, IsInt, IsPosInt, IsPosInt ] );
DeclareConstructor( "SpecialOrthogonalGroupCons",
[ IsGroup, IsInt, IsPosInt, IsRing ] );
#############################################################################
##
#F SpecialOrthogonalGroup( [<filt>, ][<e>, ]<d>, <q>[, <form>] )
#F SpecialOrthogonalGroup( [<filt>, ]<form> )
#F SO( [<filt>, ][<e>, ]<d>, <q>[, <form>] )
#F SO( [<filt>, ]<form> )
##
## <#GAPDoc Label="SpecialOrthogonalGroup">
## <ManSection>
## <Func Name="SpecialOrthogonalGroup" Arg='[filt, ][e, ]d, q[, form]'/>
## <Func Name="SpecialOrthogonalGroup" Arg='[filt, ]form' Label="for a form"/>
## <Func Name="SO" Arg='[filt, ][e, ]d, q[, form]'/>
## <Func Name="SO" Arg='[filt, ]form' Label="for a form"/>
##
## <Description>
## constructs a group isomorphic to the
## special orthogonal group SO( <A>e</A>, <A>d</A>, <A>q</A> ),
## which is the subgroup of all those matrices in the general orthogonal
## group (see <Ref Func="GeneralOrthogonalGroup"/>) that have
## determinant one, in the category given by the filter <A>filt</A>.
## (The index of SO( <A>e</A>, <A>d</A>, <A>q</A> ) in
## GO( <A>e</A>, <A>d</A>, <A>q</A> ) is <M>2</M> if <A>q</A> is
## odd, and <M>1</M> if <A>q</A> is even.)
## Also interesting is the group Omega( <A>e</A>, <A>d</A>, <A>q</A> ),
## see <Ref Oper="Omega" Label="construct an orthogonal group"/>,
## which is of index <M>2</M> in SO( <A>e</A>, <A>d</A>, <A>q</A> ),
## except in the case <M><A>d</A> = 1</M>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the special orthogonal group itself.
## <P/>
## If version at least 1.2.6 of the <Package>Forms</Package> package is
## loaded then the desired quadratic form can be specified via <A>form</A>,
## which can be either a matrix
## or a form object in <Ref Filt="IsQuadraticForm" BookName="Forms"/>
## or a group with stored <Ref Attr="InvariantQuadraticForm"/> value
## (and then this form is taken).
## <P/>
## A given <A>form</A> determines <A>e</A> and <A>d</A>, and also <A>q</A>
## except if <A>form</A> is a matrix that does not store its
## <Ref Attr="BaseDomain" Label="for a matrix object"/> value.
## These parameters can be entered, and an error is signalled if they do
## not fit to the given <A>form</A>.
## <P/>
## If <A>form</A> is not given then a default is chosen as described in the
## introduction to Section <Ref Sect="Classical Groups"/>.
## <P/>
## <Example><![CDATA[
## gap> SpecialOrthogonalGroup( 5, 3 );
## SO(0,5,3)
## gap> SpecialOrthogonalGroup( -1, 8, 2 ); # here SO and GO coincide
## GO(-1,8,2)
## gap> SpecialOrthogonalGroup( IsPermGroup, 5, 3 );
## Perm_SO(0,5,3)
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "SpecialOrthogonalGroup", function ( arg )
local filt, form;
if IsFilter( First( arg ) ) then
filt:= Remove( arg, 1 );
else
filt:= IsMatrixGroup;
fi;
if DescribesInvariantQuadraticForm( Last( arg ) ) then
form:= Remove( arg );
if Length( arg ) = 0 then
# ( [<filt>, ]<form> )
return SpecialOrthogonalGroupCons( filt, form );
elif Length( arg ) = 2 and IsPosInt( arg[1] )
and ( IsPosInt( arg[2] ) or IsRing( arg[2] ) ) then
# ( [<filt>, ]<d>, <q>, form ) or ( [<filt>, ]<d>, <R>, form )
return SpecialOrthogonalGroupCons( filt, 0, arg[1], arg[2], form );
elif Length( arg ) = 3 and IsInt( arg[1] ) and IsPosInt( arg[2] )
and ( IsPosInt( arg[3] ) or IsRing( arg[3] ) ) then
# ( [<filt>, ]<e>, <d>, <q>, form ) or ( [<filt>, ]<e>, <d>, <R>, form )
return SpecialOrthogonalGroupCons( filt, arg[1], arg[2], arg[3], form );
fi;
elif Length( arg ) = 2 and IsPosInt( arg[1] )
and ( IsPosInt( arg[2] ) or IsRing( arg[2] ) ) then
# ( [<filt>, ]<d>, <q> ) or ( [<filt>, ]<d>, <R> )
return SpecialOrthogonalGroupCons( filt, 0, arg[1], arg[2] );
elif Length( arg ) = 3 and IsInt( arg[1] ) and IsPosInt( arg[2] )
and ( IsPosInt( arg[3] ) or IsRing( arg[3] ) ) then
# ( [<filt>, ]<e>, <d>, <q> ) or ( [<filt>, ]<e>, <d>, <R> )
return SpecialOrthogonalGroupCons( filt, arg[1], arg[2], arg[3] );
fi;
Error( "usage: SpecialOrthogonalGroup( [<filt>, ][<e>, ]<d>, <q>[, <form>] )\n",
"or SpecialOrthogonalGroup( [<filt>, ]<form> )" );
end );
DeclareSynonym( "SO", SpecialOrthogonalGroup );
#############################################################################
##
#O SpecialUnitaryGroupCons( <filter>, <d>, <q> )
##
## <ManSection>
## <Oper Name="SpecialUnitaryGroupCons" Arg='filter, d, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "SpecialUnitaryGroupCons",
[ IsGroup, IsPosInt, IsPosInt ] );
#############################################################################
##
#F SpecialUnitaryGroup( [<filt>, ]<d>, <q>[, <form>] )
#F SpecialUnitaryGroup( [<filt>, ]<form> )
#F SU( [<filt>, ]<d>, <q>[, <form>] )
#F SU( [<filt>, ]<form> )
##
## <#GAPDoc Label="SpecialUnitaryGroup">
## <ManSection>
## <Func Name="SpecialUnitaryGroup" Arg='[filt, ]d, q[, form]'/>
## <Func Name="SpecialUnitaryGroup" Arg='[filt, ]form' Label="for a form"/>
## <Func Name="SU" Arg='[filt, ]d, q[, form]'/>
## <Func Name="SU" Arg='[filt, ]form' Label="for a form"/>
##
## <Description>
## constructs a group isomorphic to the special unitary group
## SU( <A>d</A>, <A>q</A> ) of those <M><A>d</A> \times <A>d</A></M>
## matrices over the field with <M><A>q</A>^2</M> elements
## whose determinant is the identity of the field and that respect a fixed
## nondegenerate sesquilinear form,
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the special unitary group itself.
## <P/>
## If version at least 1.2.6 of the <Package>Forms</Package> package is
## loaded then the desired sesquilinear form can be specified via
## <A>form</A>, which can be either a matrix
## or a form object in <Ref Filt="IsHermitianForm" BookName="Forms"/>
## or a group with stored <Ref Attr="InvariantSesquilinearForm"/> value
## (and then this form is taken).
## <P/>
## A given <A>form</A> determines <A>d</A>, and also <A>q</A>
## except if <A>form</A> is a matrix that does not store its
## <Ref Attr="BaseDomain" Label="for a matrix object"/> value.
## These parameters can be entered, and an error is signalled if they do
## not fit to the given <A>form</A>.
## <P/>
## If <A>form</A> is not given then a default is chosen as described in the
## introduction to Section <Ref Sect="Classical Groups"/>.
## <P/>
## <Example><![CDATA[
## gap> SpecialUnitaryGroup( 3, 5 );
## SU(3,5)
## gap> SpecialUnitaryGroup( IsPermGroup, 3, 5 );
## Perm_SU(3,5)
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "SpecialUnitaryGroup", function ( arg )
local filt, form;
if IsFilter( First( arg ) ) then
filt:= Remove( arg, 1 );
else
filt:= IsMatrixGroup;
fi;
if DescribesInvariantHermitianForm( Last( arg ) ) then
form:= Remove( arg );
if Length( arg ) = 0 then
# ( [<filt>, ]<form> )
return SpecialUnitaryGroupCons( filt, form );
elif Length( arg ) = 2 and IsPosInt( arg[1] ) and IsPosInt( arg[2] ) then
# ( [<filt>, ]<d>, <q>, form)
return SpecialUnitaryGroupCons( filt, arg[1], arg[2], form );
fi;
elif Length( arg ) = 2 and IsPosInt( arg[1] ) and IsPosInt( arg[2] ) then
# ( [<filt>, ]<d>, <q> )
return SpecialUnitaryGroupCons( filt, arg[1], arg[2] );
fi;
Error( "usage: SpecialUnitaryGroup( [<filt>, ]<d>, <q>[, <form>] )\n",
"or SpecialUnitaryGroup( [<filt>, ]<form> )" );
end );
DeclareSynonym( "SU", SpecialUnitaryGroup );
#############################################################################
##
#O SymplecticGroupCons( <filter>, <d>, <q> )
##
## <ManSection>
## <Oper Name="SymplecticGroupCons" Arg='filter, d, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "SymplecticGroupCons", [ IsGroup, IsPosInt, IsPosInt ] );
DeclareConstructor( "SymplecticGroupCons", [ IsGroup, IsPosInt, IsRing ] );
#############################################################################
##
#F SymplecticGroup( [<filt>, ]<d>, <q>[, <form>] ) . . . . symplectic group
#F SymplecticGroup( [<filt>, ]<form> ) . . . . . . . . . . symplectic group
#F Sp( [<filt>, ]<d>, <q>[, <form>] )
#F Sp( [<filt>, ]<form> )
#F SP( [<filt>, ]<d>, <q>[, <form>] )
#F SP( [<filt>, ]<form> )
##
## <#GAPDoc Label="SymplecticGroup">
## <ManSection>
## <Heading>SymplecticGroup</Heading>
## <Func Name="SymplecticGroup" Arg='[filt, ]d, q[, form]'
## Label="for dimension and field size"/>
## <Func Name="SymplecticGroup" Arg='[filt, ]d, ring[, form]'
## Label="for dimension and a ring"/>
## <Func Name="SymplecticGroup" Arg='[filt, ]form'
## Label="for form"/>
## <Func Name="Sp" Arg='[filt, ]d, q[, form]'
## Label="for dimension and field size"/>
## <Func Name="Sp" Arg='[filt, ]d, ring[, form]'
## Label="for dimension and a ring"/>
## <Func Name="Sp" Arg='[filt, ]form'
## Label="for form"/>
## <Func Name="SP" Arg='[filt, ]d, q[, form]'
## Label="for dimension and field size"/>
## <Func Name="SP" Arg='[filt, ]d, ring[, form]'
## Label="for dimension and a ring"/>
## <Func Name="SP" Arg='[filt, ]form'
## Label="for form"/>
##
## <Description>
## constructs a group isomorphic to the symplectic group
## Sp( <A>d</A>, <A>q</A> ) of those <M><A>d</A> \times <A>d</A></M>
## matrices over the field with <A>q</A> elements (respectively the ring
## <A>ring</A>)
## that respect a fixed nondegenerate symplectic form,
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the symplectic group itself.
## <P/>
## At the moment finite fields or residue class rings
## <C>Integers mod <A>q</A></C>, with <A>q</A> an odd prime power, are
## supported.
## <P/>
## If version at least 1.2.6 of the <Package>Forms</Package> package is
## loaded and the arguments describe a matrix group over a finite field then
## the desired bilinear form can be specified via <A>form</A>,
## which can be either a matrix
## or a form object in <Ref Filt="IsBilinearForm" BookName="Forms"/>
## or a group with stored <Ref Attr="InvariantBilinearForm"/> value
## (and then this form is taken).
## <P/>
## A given <A>form</A> determines and <A>d</A>, and also <A>q</A>
## except if <A>form</A> is a matrix that does not store its
## <Ref Attr="BaseDomain" Label="for a matrix object"/> value.
## These parameters can be entered, and an error is signalled if they do
## not fit to the given <A>form</A>.
## <P/>
## If <A>form</A> is not given then a default is chosen as described in the
## introduction to Section <Ref Sect="Classical Groups"/>.
## <P/>
## <Example><![CDATA[
## gap> SymplecticGroup( 4, 2 );
## Sp(4,2)
## gap> g:=SymplecticGroup(6,Integers mod 9);
## Sp(6,Z/9Z)
## gap> Size(g);
## 95928796265538862080
## gap> SymplecticGroup( IsPermGroup, 4, 2 );
## Perm_Sp(4,2)
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "DescribesInvariantBilinearForm",
obj -> IsMatrixOrMatrixObj( obj ) or
( IsBoundGlobal( "IsBilinearForm" ) and
ValueGlobal( "IsBilinearForm" )( obj ) ) or
( IsGroup( obj ) and HasInvariantBilinearForm( obj ) ) );
BindGlobal( "SymplecticGroup", function ( arg )
local filt, form;
if IsFilter( First( arg ) ) then
filt:= Remove( arg, 1 );
else
filt:= IsMatrixGroup;
fi;
if DescribesInvariantBilinearForm( Last( arg ) ) then
form:= Remove( arg );
if Length( arg ) = 0 then
# ( [<filt>, ]<form> )
return SymplecticGroupCons( filt, form );
elif Length( arg ) = 2 and IsPosInt( arg[1] )
and ( IsPosInt( arg[2] ) or IsRing( arg[2] ) ) then
# ( [<filt>, ]<d>, <q>, <form> ) or ( [<filt>, ]<d>, <R>, <form> )
return SymplecticGroupCons( filt, arg[1], arg[2], form );
fi;
elif Length( arg ) = 2 and IsPosInt( arg[1] )
and ( IsPosInt( arg[2] ) or IsRing( arg[2] ) ) then
# ( [<filt>, ]<d>, <q> ) or ( [<filt>, ]<d>, <R> )
return SymplecticGroupCons( filt, arg[1], arg[2] );
fi;
Error( "usage: SymplecticGroup( [<filt>, ]<d>, <q>[, <form>] )\n",
"or SymplecticGroup( [<filt>, ]<d>, <R>[, <form>] )\n",
"or SymplecticGroup( [<filt>, ]<form> )" );
end );
DeclareSynonym( "Sp", SymplecticGroup );
DeclareSynonym( "SP", SymplecticGroup );
#############################################################################
##
#O OmegaCons( <filter>, <e>, <d>, <q> ) . . . . . . . . . orthogonal group
##
## <ManSection>
## <Oper Name="OmegaCons" Arg='filter, d, e, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "OmegaCons", [ IsGroup, IsInt, IsPosInt, IsPosInt ] );
#############################################################################
##
#O Omega( [<filt>, ][<e>, ]<d>, <q>[, <form>] )
#O Omega( [<filt>, ]<form> )
##
## <#GAPDoc Label="Omega_orthogonal_groups">
## <ManSection>
## <Oper Name="Omega" Arg='[filt, ][e, ]d, q[, form]'
## Label="construct an orthogonal group"/>
## <Oper Name="Omega" Arg='[filt, ]form'
## Label="construct an orthogonal group for a given quadratic form"/>
##
## <Description>
## constructs a group isomorphic to the
## group <M>\Omega</M>( <A>e</A>, <A>d</A>, <A>q</A> ) of those
## <M><A>d</A> \times <A>d</A></M> matrices over the field with <A>q</A>
## elements that respect a non-singular quadratic form
## (see <Ref Attr="InvariantQuadraticForm"/>) specified by <A>e</A>,
## and that have square spinor norm in odd characteristic
## or Dickson invariant <M>0</M> in even characteristic, respectively,
## in the category given by the filter <A>filt</A>.
## <P/>
## For odd <A>q</A> and <M><A>d</A> \geq 2</M>, this group has always
## index two in the corresponding special orthogonal group,
## which will be conjugate in <M>GL(d,q)</M> to the group returned by
## SO( <A>e</A>, <A>d</A>, <A>q</A> ),
## see <Ref Func="SpecialOrthogonalGroup"/>,
## but may fix a different form (see <Ref Sect="Classical Groups"/>).
## <P/>
## The value of <A>e</A> must be <M>0</M> for odd <A>d</A> (and can
## optionally be omitted in this case), respectively one of <M>1</M> or
## <M>-1</M> for even <A>d</A>.
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group is the group
## <M>\Omega</M>( <A>e</A>, <A>d</A>, <A>q</A> ) itself.
## <P/>
## If version at least 1.2.6 of the <Package>Forms</Package> package is
## loaded then the desired quadratic form can be specified via <A>form</A>,
## which can be either a matrix
## or a form object in <Ref Filt="IsQuadraticForm" BookName="Forms"/>
## or a group with stored <Ref Attr="InvariantQuadraticForm"/> value
## (and then this form is taken).
## <P/>
## A given <A>form</A> determines <A>e</A> and <A>d</A>, and also <A>q</A>
## except if <A>form</A> is a matrix that does not store its
## <Ref Attr="BaseDomain" Label="for a matrix object"/> value.
## These parameters can be entered, and an error is signalled if they do
## not fit to the given <A>form</A>.
## <P/>
## If <A>form</A> is not given then a default is chosen as described in the
## introduction to Section <Ref Sect="Classical Groups"/>.
## <P/>
## <Example><![CDATA[
## gap> g:= Omega( 3, 5 ); StructureDescription( g );
## Omega(0,3,5)
## "A5"
## gap> g:= Omega( 1, 4, 4 ); StructureDescription( g );
## Omega(+1,4,4)
## "A5 x A5"
## gap> g:= Omega( -1, 4, 3 ); StructureDescription( g );
## Omega(-1,4,3)
## "A6"
## gap> g:= Omega( IsPermGroup, 1, 6, 2 ); StructureDescription( g );
## Perm_Omega(+1,6,2)
## "A8"
## gap> IsSubset( GO( 3, 5 ), Omega( 3, 5 ) ); # different forms!
## false
## ]]></Example>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DeclareOperation( "Omega", [ IsPosInt, IsPosInt ] );
DeclareOperation( "Omega", [ IsInt, IsPosInt, IsPosInt ] );
DeclareOperation( "Omega", [ IsFunction, IsPosInt, IsPosInt ] );
DeclareOperation( "Omega", [ IsFunction, IsInt, IsPosInt, IsPosInt ] );
DeclareOperation( "Omega", [ IsPosInt, IsRing ] );
DeclareOperation( "Omega", [ IsInt, IsPosInt, IsRing ] );
DeclareOperation( "Omega", [ IsFunction, IsPosInt, IsRing ] );
DeclareOperation( "Omega", [ IsFunction, IsInt, IsPosInt, IsRing ] );
#############################################################################
##
#O GeneralSemilinearGroupCons( <filter>, <d>, <q> )
##
## <ManSection>
## <Oper Name="GeneralSemilinearGroupCons" Arg='filter, d, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "GeneralSemilinearGroupCons",
[ IsGroup, IsPosInt, IsPosInt ] );
#############################################################################
##
#F GeneralSemilinearGroup( [<filt>, ]<d>, <q> ) . general semilinear group
#F GammaL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="GeneralSemilinearGroup">
## <ManSection>
## <Func Name="GeneralSemilinearGroup" Arg='[filt, ]d, q'/>
## <Func Name="GammaL" Arg='[filt, ]d, q'/>
##
## <Description>
## <Ref Func="GeneralSemilinearGroup"/> returns a group isomorphic to the
## general semilinear group <M>\Gamma</M>L( <A>d</A>, <A>q</A> ) of
## semilinear mappings of the vector space
## <C>GF( </C><A>q</A><C> )^</C><A>d</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group consists of matrices of dimension
## <A>d</A> <M>f</M> over the field with <M>p</M> elements,
## where <A>q</A> <M>= p^f</M>, for a prime integer <M>p</M>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "GeneralSemilinearGroup", function( arg )
if Length( arg ) = 2 then
return GeneralSemilinearGroupCons( IsMatrixGroup, arg[1], arg[2] );
elif Length( arg ) = 3 and IsOperation( arg[1] ) then
return GeneralSemilinearGroupCons( arg[1], arg[2], arg[3] );
fi;
Error( "usage: GeneralSemilinearGroup( [<filter>, ]<d>, <q> )" );
end );
DeclareSynonym( "GammaL", GeneralSemilinearGroup );
#############################################################################
##
#O SpecialSemilinearGroupCons( <filter>, <d>, <q> )
##
## <ManSection>
## <Oper Name="SpecialSemilinearGroupCons" Arg='filter, d, q'/>
##
## <Description>
## </Description>
## </ManSection>
##
DeclareConstructor( "SpecialSemilinearGroupCons",
[ IsGroup, IsPosInt, IsPosInt ] );
#############################################################################
##
#F SpecialSemilinearGroup( [<filt>, ]<d>, <q> ) . special semilinear group
#F SigmaL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="SpecialSemilinearGroup">
## <ManSection>
## <Func Name="SpecialSemilinearGroup" Arg='[filt, ]d, q'/>
## <Func Name="SigmaL" Arg='[filt, ]d, q'/>
##
## <Description>
## <Ref Func="SpecialSemilinearGroup"/> returns a group isomorphic to the
## special semilinear group <M>\Sigma</M>L( <A>d</A>, <A>q</A> ) of those
## semilinear mappings of the vector space
## <C>GF( </C><A>q</A><C> )^</C><A>d</A>
## (see <Ref Func="GeneralSemilinearGroup"/>)
## whose linear part has determinant one.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsMatrixGroup"/>,
## and the returned group consists of matrices of dimension
## <A>d</A> <M>f</M> over the field with <M>p</M> elements,
## where <A>q</A> <M>= p^f</M>, for a prime integer <M>p</M>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
BindGlobal( "SpecialSemilinearGroup", function( arg )
if Length( arg ) = 2 then
return SpecialSemilinearGroupCons( IsMatrixGroup, arg[1], arg[2] );
elif Length( arg ) = 3 and IsOperation( arg[1] ) then
return SpecialSemilinearGroupCons( arg[1], arg[2], arg[3] );
fi;
Error( "usage: SpecialSemilinearGroup( [<filter>, ]<d>, <q> )" );
end );
DeclareSynonym( "SigmaL", SpecialSemilinearGroup );
#############################################################################
##
#F DECLARE_PROJECTIVE_GROUPS_OPERATION( ... )
##
BindGlobal("DECLARE_PROJECTIVE_GROUPS_OPERATION",
# (<name>,<abbreviation>,<fieldextdeg>,<sizefunc-or-fail>)
function(nam,abbr,extdeg,szf)
local pnam,cons,opr;
opr:=VALUE_GLOBAL(nam);
pnam:=Concatenation("Projective",nam);
cons:=NewConstructor(Concatenation(pnam,"Cons"),[IsGroup,IsInt,IsInt]);
BindGlobal(Concatenation(pnam,"Cons"),cons);
BindGlobal(pnam,function(arg)
if Length(arg) = 2 then
return cons( IsPermGroup, arg[1], arg[2] );
elif IsOperation(arg[1]) then
if Length(arg) = 3 then
return cons( arg[1], arg[2], arg[3] );
fi;
fi;
Error( "usage: ",pnam,"( [<filter>, ]<d>, <q> )" );
end );
DeclareSynonym(Concatenation("P",abbr),VALUE_GLOBAL(pnam));
# install a method to get the permutation action on lines
InstallMethod( cons,"action on lines",
[ IsPermGroup, IsPosInt,IsPosInt ],
function(fil,n,q)
local g,f,p;
g:=opr(IsMatrixGroup,n,q);
f:=GF(q^extdeg);
p:=ProjectiveActionOnFullSpace(g,f,n);
if szf<>fail then
SetSize(p,szf(n,q,g));
fi;
return p;
end);
end);
#############################################################################
##
#F ProjectiveGeneralLinearGroup( [<filt>, ]<d>, <q> )
#F PGL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveGeneralLinearGroup">
## <ManSection>
## <Func Name="ProjectiveGeneralLinearGroup" Arg='[filt, ]d, q'/>
## <Func Name="PGL" Arg='[filt, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective general linear group
## PGL( <A>d</A>, <A>q</A> ) of those <M><A>d</A> \times <A>d</A></M>
## matrices over the field with <A>q</A> elements, modulo the
## centre, in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## <P/>
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_GROUPS_OPERATION("GeneralLinearGroup","GL",1,
# size function
function(n,q,g)
return Size(g)/(q-1);
end);
#############################################################################
##
#F ProjectiveSpecialLinearGroup( [<filt>, ]<d>, <q> )
#F PSL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveSpecialLinearGroup">
## <ManSection>
## <Func Name="ProjectiveSpecialLinearGroup" Arg='[filt, ]d, q'/>
## <Func Name="PSL" Arg='[filt, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective special linear group
## PSL( <A>d</A>, <A>q</A> ) of those <M><A>d</A> \times <A>d</A></M>
## matrices over the field with <A>q</A> elements whose determinant is the
## identity of the field, modulo the centre,
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_GROUPS_OPERATION("SpecialLinearGroup","SL",1,
# size function
function(n,q,g)
return Size(g)/Gcd(n,q-1);
end);
#############################################################################
##
#F ProjectiveGeneralUnitaryGroup( [<filt>, ]<d>, <q> )
#F PGU( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveGeneralUnitaryGroup">
## <ManSection>
## <Func Name="ProjectiveGeneralUnitaryGroup" Arg='[filt, ]d, q'/>
## <Func Name="PGU" Arg='[filt, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective general unitary group
## PGU( <A>d</A>, <A>q</A> ) of those <M><A>d</A> \times <A>d</A></M>
## matrices over the field with <M><A>q</A>^2</M> elements that respect
## a fixed nondegenerate sesquilinear form,
## modulo the centre, in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_GROUPS_OPERATION("GeneralUnitaryGroup","GU",2,
# size function
function(n,q,g)
return Size(g)/(q+1);
end);
#############################################################################
##
#F ProjectiveSpecialUnitaryGroup( [<filt>, ]<d>, <q> )
#F PSU( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveSpecialUnitaryGroup">
## <ManSection>
## <Func Name="ProjectiveSpecialUnitaryGroup" Arg='[filt, ]d, q'/>
## <Func Name="PSU" Arg='[filt, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective special unitary group
## PSU( <A>d</A>, <A>q</A> ) of those <M><A>d</A> \times <A>d</A></M>
## matrices over the field with <M><A>q</A>^2</M> elements that respect
## a fixed nondegenerate sesquilinear form and have determinant 1,
## modulo the centre, in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_GROUPS_OPERATION("SpecialUnitaryGroup","SU",2,
# size function
function(n,q,g)
return Size(g)/Gcd(n,q+1);
end);
#############################################################################
##
#F ProjectiveSymplecticGroup( [<filt>, ]<d>, <q> )
#F PSP( [<filt>, ]<d>, <q> )
#F PSp( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveSymplecticGroup">
## <ManSection>
## <Func Name="ProjectiveSymplecticGroup" Arg='[filt, ]d, q'/>
## <Func Name="PSP" Arg='[filt, ]d, q'/>
## <Func Name="PSp" Arg='[filt, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective symplectic group
## PSp(<A>d</A>,<A>q</A>) of those <M><A>d</A> \times <A>d</A></M> matrices
## over the field with <A>q</A> elements that respect a fixed nondegenerate
## symplectic form, modulo the centre,
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_GROUPS_OPERATION("SymplecticGroup","SP",1,
# size function
function(n,q,g)
return Size(g)/Gcd(2,q-1);
end);
DeclareSynonym( "PSp", PSP );
#############################################################################
##
#F DECLARE_PROJECTIVE_ORTHOGONAL_GROUPS_OPERATION( ... )
##
BindGlobal("DECLARE_PROJECTIVE_ORTHOGONAL_GROUPS_OPERATION",
# ( <name>, <abbreviation>, <sizefunc-or-fail> )
function( nam, abbr, szf )
local pnam,cons,opr;
opr:= VALUE_GLOBAL( nam );
pnam:= Concatenation( "Projective", nam );
cons:= NewConstructor( Concatenation( pnam, "Cons" ),
[ IsGroup, IsInt, IsInt, IsInt ] );
BindGlobal( Concatenation( pnam, "Cons" ), cons );
BindGlobal( pnam, function( arg )
if Length( arg ) = 2 then
return cons( IsPermGroup, 0, arg[1], arg[2] );
elif Length( arg ) = 3 and ForAll( arg, IsInt ) then
return cons( IsPermGroup, arg[1], arg[2], arg[3] );
elif IsOperation( arg[1] ) then
if Length( arg ) = 3 then
return cons( arg[1], 0, arg[2], arg[3] );
elif Length( arg ) = 4 then
return cons( arg[1], arg[2], arg[3], arg[4] );
fi;
fi;
Error( "usage: ", pnam, "( [<filter>, ][<e>, ]<d>, <q> )" );
end );
DeclareSynonym( Concatenation( "P", abbr ), VALUE_GLOBAL( pnam ) );
# Install a method to get the permutation action on lines.
InstallMethod( cons, "action on lines",
[ IsPermGroup, IsInt, IsPosInt, IsPosInt ],
function( filter, e, n, q )
local g, p;
g:= opr( IsMatrixGroup, e, n, q );
p:= ProjectiveActionOnFullSpace( g, GF( q ), n );
if szf <> fail then
SetSize( p, szf( e, n, q, g ) );
fi;
return p;
end );
end );
#############################################################################
##
#F ProjectiveGeneralOrthogonalGroup( [<filt>, ][<e>, ]<d>, <q> )
#F PGO( [<filt>, ][<e>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveGeneralOrthogonalGroup">
## <ManSection>
## <Func Name="ProjectiveGeneralOrthogonalGroup" Arg='[filt, ][e, ]d, q'/>
## <Func Name="PGO" Arg='[filt, ][e, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective group
## PGO( <A>e</A>, <A>d</A>, <A>q</A> )
## of GO( <A>e</A>, <A>d</A>, <A>q</A> ),
## modulo the centre
## (see <Ref Func="GeneralOrthogonalGroup"/>),
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_ORTHOGONAL_GROUPS_OPERATION( "GeneralOrthogonalGroup", "GO",
function( e, n, q, g )
if ( n mod 2 = 0 and ( q^(n/2) - e ) mod 2 = 0 ) or
( n mod 2 = 1 and ( q - 1 ) mod 2 = 0 ) then
return Size( g ) / 2;
else
return Size( g );
fi;
end );
#############################################################################
##
#F ProjectiveSpecialOrthogonalGroup( [<filt>, ][<e>, ]<d>, <q> )
#F PSO( [<filt>, ][<e>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveSpecialOrthogonalGroup">
## <ManSection>
## <Func Name="ProjectiveSpecialOrthogonalGroup" Arg='[filt, ][e, ]d, q'/>
## <Func Name="PSO" Arg='[filt, ][e, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective group
## PSO( <A>e</A>, <A>d</A>, <A>q</A> )
## of SO( <A>e</A>, <A>d</A>, <A>q</A> ),
## modulo the centre
## (see <Ref Func="SpecialOrthogonalGroup"/>),
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_ORTHOGONAL_GROUPS_OPERATION( "SpecialOrthogonalGroup", "SO",
function( e, n, q, g )
if n mod 2 = 0 and ( q^(n/2) - e ) mod 2 = 0 then
return Size( g ) / 2;
else
return Size( g );
fi;
end );
#############################################################################
##
#F ProjectiveOmega( [<filt>, ][<e>, ]<d>, <q> )
#F POmega( [<filt>, ][<e>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveOmega">
## <ManSection>
## <Func Name="ProjectiveOmega" Arg='[filt, ][e, ]d, q'/>
## <Func Name="POmega" Arg='[filt, ][e, ]d, q'/>
##
## <Description>
## constructs a group isomorphic to the projective group
## P<M>\Omega</M>( <A>e</A>, <A>d</A>, <A>q</A> )
## of <M>\Omega</M>( <A>e</A>, <A>d</A>, <A>q</A> ),
## modulo the centre
## (see <Ref Oper="Omega" Label="construct an orthogonal group"/>),
## in the category given by the filter <A>filt</A>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_ORTHOGONAL_GROUPS_OPERATION( "Omega", "Omega",
function( e, n, q, g )
if n mod 2 = 0 and ( q^(n/2) - e ) mod 4 = 0 then
return Size( g ) / 2;
else
return Size( g );
fi;
end );
#############################################################################
##
#F DECLARE_PROJECTIVE_SEMILINEAR_GROUPS_OPERATION( ... )
##
BindGlobal( "DECLARE_PROJECTIVE_SEMILINEAR_GROUPS_OPERATION",
function( name, abbrname, lineargroup, sizefun )
local opr, pname, consname, cons;
opr:= VALUE_GLOBAL( name );
pname:= Concatenation( "Projective", name );
consname:= Concatenation( pname, "Cons" );
DeclareConstructor( consname, [ IsGroup, IsInt, IsInt ] );
cons:= ValueGlobal( consname );
BindGlobal( pname, function( arg )
if Length( arg ) = 2 then
return cons( IsPermGroup, arg[1], arg[2] );
elif IsOperation( arg[1] ) then
if Length( arg ) = 3 then
return cons( arg[1], arg[2], arg[3] );
fi;
fi;
Error( "usage: ", pname, "( [<filter>, ]<d>, <q> )" );
end );
DeclareSynonym( Concatenation( "P", abbrname ), VALUE_GLOBAL( pname ) );
# Install a method to get the permutation action on lines.
InstallMethod( cons,
"action on lines",
[ IsPermGroup, IsPosInt, IsPosInt ],
function( filt, n, q )
local lin, facts, d, p, F, points, gens, indices, g;
lin:= lineargroup( IsMatrixGroup, n, q );
facts:= Factors( Integers, q );
d:= Length( facts );
p:= facts[1];
if n = 1 then
return CyclicGroup( filt, d );
fi;
F:= GF( q );
points:= Set( NormedRowVectors( F^n ), v -> ImmutableVector( F, v ) );
gens:= List( GeneratorsOfGroup( lin ),
mat -> Permutation( mat, points, OnLines ) );
# Apply the field automorphism to the normed vectors.
if d > 1 then
Apply( points, v -> ImmutableVector( F, List( v, x -> x^p ) ) );
indices:= [ 1 .. Length( points ) ];
SortParallel( points, indices );
Add( gens, PermList( indices ) );
fi;
g:= GroupWithGenerators( gens );
SetSize( g, sizefun( n, q, d, lin ) );
return g;
end );
end );
#############################################################################
##
#F ProjectiveGeneralSemilinearGroup( [<filt>, ]<d>, <q> )
#F PGammaL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveGeneralSemilinearGroup">
## <ManSection>
## <Func Name="ProjectiveGeneralSemilinearGroup" Arg='[filt, ]d, q'/>
## <Func Name="PGammaL" Arg='[filt, ]d, q'/>
##
## <Description>
## <Ref Func="ProjectiveGeneralSemilinearGroup"/> returns a group
## isomorphic to the factor group of the general semilinear group
## <C>GammaL(</C> <A>d</A>, <A>q</A> <C>)</C> modulo the center of its
## normal subgroup <C>GL(</C> <A>d</A>, <A>q</A> <C>)</C>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space <C>GF(</C><A>q</A><C>)^</C><A>d</A>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_SEMILINEAR_GROUPS_OPERATION( "GeneralSemilinearGroup",
"GammaL", GL, { n, q, d, lin } -> d * Size( lin ) / (q-1) );
#############################################################################
##
#F ProjectiveSpecialSemilinearGroup( [<filt>, ]<d>, <q> )
#F PSigmaL( [<filt>, ]<d>, <q> )
##
## <#GAPDoc Label="ProjectiveSpecialSemilinearGroup">
## <ManSection>
## <Func Name="ProjectiveSpecialSemilinearGroup" Arg='[filt, ]d, q'/>
## <Func Name="PSigmaL" Arg='[filt, ]d, q'/>
##
## <Description>
## <Ref Func="ProjectiveSpecialSemilinearGroup"/> returns a group
## isomorphic to the factor group of the special semilinear group
## <C>SigmaL(</C> <A>d</A>, <A>q</A> <C>)</C> modulo the center of its
## normal subgroup <C>SL(</C> <A>d</A>, <A>q</A> <C>)</C>.
## <P/>
## If <A>filt</A> is not given it defaults to <Ref Filt="IsPermGroup"/>,
## and the returned group is the action on lines of the underlying vector
## space <C>GF(</C><A>q</A><C>)^</C><A>d</A>.
## </Description>
## </ManSection>
## <#/GAPDoc>
##
DECLARE_PROJECTIVE_SEMILINEAR_GROUPS_OPERATION( "SpecialSemilinearGroup",
"SigmaL", SL, { n, q, d, lin } -> d * Size( lin ) / Gcd( n, q-1 ) );
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