Examples and Tests
Dummy category
gap> LoadPackage( "CAP", false ); true gap> dummy := DummyCategory( rec( > list_of_operations_to_install := [ "PreCompose", "IdentityMorphism", "DirectSum" ], > properties := [ "IsAdditiveCategory" ], > ) );; gap> CanCompute( dummy, "DirectSum" ); true gap> IsAdditiveCategory( dummy ); true
Functors We create a binary functor F with one covariant and one contravariant component in two ways. Here is the first way to model a binary functor:
gap> field := HomalgFieldOfRationals( );; gap> vec := LeftPresentations( field );; gap> F := CapFunctor( "CohomForVec", [ vec, [ vec, true ] ], vec );; gap> obj_func := function( A, B ) return TensorProductOnObjects( A, DualOnObjects( B ) ); end;; gap> mor_func := function( source, alpha, beta, range ) return TensorProductOnMorphismsWithGivenTensorProducts( source, alpha, DualOnMorphisms( beta ), range ); end;; gap> AddObjectFunction( F, obj_func );; gap> AddMorphismFunction( F, mor_func );;
CAP regards F as a binary functor on a technical level, as we can see by looking at its input signature:
gap> InputSignature( F ); [ [ Category of left presentations of Q, false ], [ Category of left presentations of Q, true ] ]
We can see that ApplyFunctor works both on two arguments and on one argument (in the product category).
gap> V1 := TensorUnit( vec );; gap> V3 := DirectSum( V1, V1, V1 );; gap> pi1 := ProjectionInFactorOfDirectSum( [ V1, V1 ], 1 );; gap> pi2 := ProjectionInFactorOfDirectSum( [ V3, V1 ], 1 );; gap> value1 := ApplyFunctor( F, pi1, pi2 );; gap> input := Product( pi1, Opposite( pi2 ) );; gap> value2 := ApplyFunctor( F, input );; gap> IsCongruentForMorphisms( value1, value2 ); true
Here is the second way to model a binary functor:
gap> F2 := CapFunctor( "CohomForVec2", Product( vec, Opposite( vec ) ), vec );; gap> AddObjectFunction( F2, a -> obj_func( a[1], Opposite( a[2] ) ) );; gap> AddMorphismFunction( F2, function( source, datum, range ) return mor_func( source, datum[1], Opposite( datum[2] ), range ); end );; gap> value3 := ApplyFunctor( F2,input );; gap> IsCongruentForMorphisms( value1, value3 ); true
CAP regards F2 as a unary functor on a technical level, as we can see by looking at its input signature:
gap> InputSignature( F2 ); [ [ Product of: Category of left presentations of Q, Opposite of Category of left presentations of Q, false ] ]
Installation of the first functor as a GAP-operation. It will be installed both as a unary and binary version.
gap> InstallFunctor( F, "F_installation" );; gap> F_installation( pi1, pi2 );; gap> F_installation( input );; gap> F_installationOnObjects( V1, V1 );; gap> F_installationOnObjects( Product( V1, Opposite( V1 ) ) );; gap> F_installationOnMorphisms( pi1, pi2 );; gap> F_installationOnMorphisms( input );;
Installation of the second functor as a GAP-operation. It will be installed only as a unary version.
gap> InstallFunctor( F2, "F_installation2" );; gap> F_installation2( input );; gap> F_installation2OnObjects( Product( V1, Opposite( V1 ) ) );; gap> F_installation2OnMorphisms( input );;
HandlePrecompiledTowers
gap> LoadPackage( "CAP", false ); true gap> dummy1 := CreateCapCategory( );; gap> dummy2 := CreateCapCategory( );; gap> dummy3 := CreateCapCategory( );; gap> DisplayAndReturn := function ( string ) > Display( string ); return string; end;; gap> dummy1!.compiler_hints := rec( );; gap> dummy1!.compiler_hints.precompiled_towers := [ > rec( > remaining_constructors_in_tower := [ "Constructor1" ], > precompiled_functions_adder := cat -> > DisplayAndReturn( "Adding precompiled operations for Constructor1" ), > ), > rec( > remaining_constructors_in_tower := [ "Constructor1", "Constructor2" ], > precompiled_functions_adder := cat -> > DisplayAndReturn( "Adding precompiled operations for Constructor2" ), > ), > ];; gap> HandlePrecompiledTowers( dummy2, dummy1, "Constructor1" ); Adding precompiled operations for Constructor1 gap> HandlePrecompiledTowers( dummy3, dummy2, "Constructor2" ); Adding precompiled operations for Constructor2
Homomorphism structure
gap> ReadPackage( "CAP", "examples/FieldAsCategory.g" );; gap> Q := HomalgFieldOfRationals();; gap> Qoid := FieldAsCategory( Q );; gap> a := FieldAsCategoryMorphism( 1/2, Qoid );; gap> b := FieldAsCategoryMorphism( -2/3, Qoid );; gap> u := FieldAsCategoryUniqueObject( Qoid );; gap> IsCongruentForMorphisms( a, > InterpretMorphismFromDistinguishedObjectToHomomorphismStructureAsMorphism( > u,u, > InterpretMorphismAsMorphismFromDistinguishedObjectToHomomorphismStructure( > a > ) > ) > ); true gap> a = HomStructure( u, u, HomStructure( a ) ); true gap> IsEqualForObjects( HomStructure( Qoid ), DistinguishedObjectOfHomomorphismStructure( Qoid ) ); true gap> c := FieldAsCategoryMorphism( 3, Qoid );; gap> d := FieldAsCategoryMorphism( 0, Qoid );; gap> left_coeffs := [ [ a, b ], [ c, d ] ];; gap> right_coeffs := [ [ PreCompose( a, b ), PreCompose( b, c ) ], [ c, PreCompose( a, a ) ] ];; gap> right_side := [ a, b ];; gap> MereExistenceOfSolutionOfLinearSystemInAbCategory( left_coeffs, right_coeffs, right_side ); true gap> solution := > SolveLinearSystemInAbCategory( > left_coeffs, > right_coeffs, > right_side > );; gap> ForAll( [ 1, 2 ], i -> > IsCongruentForMorphisms( > Sum( List( [ 1, 2 ], j -> PreCompose( [ left_coeffs[i][j], solution[j], right_coeffs[i][j] ] ) ) ), > right_side[i] > ) > ); true gap> IsLiftable( c, d ); false gap> LiftOrFail( c, d ); fail gap> IsLiftable( d, c ); true gap> LiftOrFail( d, c ); 0 gap> Lift( d, c ); 0 gap> IsColiftable( c, d ); true gap> ColiftOrFail( c, d ); 0 gap> Colift( c, d ); 0 gap> IsColiftable( d, c ); false gap> ColiftOrFail( d, c ); fail
gap> ReadPackage( "CAP", "examples/StringsAsCategory.g" );; gap> C := StringsAsCategory();; gap> obj1 := StringsAsCategoryObject( "qaeiou", C );; gap> obj2 := StringsAsCategoryObject( "qxayeziouT", C );; gap> mor := StringsAsCategoryMorphism( obj1, "xyzaTe", obj2 );; gap> IsWellDefined( mor ); true gap> ## Test SimplifyObject > IsEqualForObjects( SimplifyObject( obj1, 0 ), obj1 ); true gap> IsEqualForObjects( SimplifyObject( obj1, 1 ), obj1 ); false gap> ForAny( [0,1,2,3,4], i -> IsEqualForObjects( SimplifyObject( obj1, i ), SimplifyObject( obj1, i + 1 ) ) ); false gap> ForAll( [5,6,7,8], i -> IsEqualForObjects( SimplifyObject( obj1, i ), SimplifyObject( obj1, i + 1 ) ) ); true gap> ## Test SimplifyMorphism > IsEqualForMorphisms( SimplifyMorphism( mor, 0 ), mor ); true gap> IsEqualForMorphisms( SimplifyMorphism( mor, 1 ), mor ); false gap> ForAny( [0,1], i -> IsEqualForMorphisms( SimplifyMorphism( mor, i ), SimplifyMorphism( mor, i + 1 ) ) ); false gap> ForAll( [2,3,4,5], i -> IsEqualForMorphisms( SimplifyMorphism( mor, i ), SimplifyMorphism( mor, i + 1 ) ) ); true gap> ## Test SimplifySource > IsEqualForMorphismsOnMor( SimplifySource( mor, 0 ), mor ); true gap> IsEqualForMorphismsOnMor( SimplifySource( mor, 1 ), mor ); false gap> ForAny( [0,1,2,3,4], i -> IsEqualForMorphismsOnMor( SimplifySource( mor, i ), SimplifySource( mor, i + 1 ) ) ); false gap> ForAll( [5,6,7,8,9], i -> IsEqualForMorphismsOnMor( SimplifySource( mor, i ), SimplifySource( mor, i + 1 ) ) ); true gap> IsCongruentForMorphisms( > PreCompose( SimplifySource_IsoFromInputObject( mor, infinity ), SimplifySource( mor, infinity ) ), mor > ); true gap> IsCongruentForMorphisms( > PreCompose( SimplifySource_IsoToInputObject( mor, infinity ), mor ) , SimplifySource( mor, infinity ) > ); true gap> ## Test SimplifyRange > IsEqualForMorphismsOnMor( SimplifyRange( mor, 0 ), mor ); true gap> IsEqualForMorphismsOnMor( SimplifyRange( mor, 1 ), mor ); false gap> ForAny( [0,1,2,3,4], i -> IsEqualForMorphismsOnMor( SimplifyRange( mor, i ), SimplifyRange( mor, i + 1 ) ) ); false gap> ForAll( [5,6,7,8,9], i -> IsEqualForMorphismsOnMor( SimplifyRange( mor, i ), SimplifyRange( mor, i + 1 ) ) ); true gap> IsCongruentForMorphisms( > PreCompose( SimplifyRange( mor, infinity ), SimplifyRange_IsoToInputObject( mor, infinity ) ), mor > ); true gap> IsCongruentForMorphisms( > PreCompose( mor, SimplifyRange_IsoFromInputObject( mor, infinity ) ), SimplifyRange( mor, infinity ) > ); true gap> ## Test SimplifySourceAndRange > IsEqualForMorphismsOnMor( SimplifySourceAndRange( mor, 0 ), mor ); true gap> IsEqualForMorphismsOnMor( SimplifySourceAndRange( mor, 1 ), mor ); false gap> ForAny( [0,1,2,3,4], i -> IsEqualForMorphismsOnMor( SimplifySourceAndRange( mor, i ), SimplifySourceAndRange( mor, i + 1 ) ) ); false gap> ForAll( [5,6,7,8,9], i -> IsEqualForMorphismsOnMor( SimplifySourceAndRange( mor, i ), SimplifySourceAndRange( mor, i + 1 ) ) ); true gap> IsCongruentForMorphisms( > mor, > PreCompose( [ SimplifySourceAndRange_IsoFromInputSource( mor, infinity ), > SimplifySourceAndRange( mor, infinity ), > SimplifySourceAndRange_IsoToInputRange( mor, infinity ) ] ) > ); true gap> IsCongruentForMorphisms( > SimplifySourceAndRange( mor, infinity ), > PreCompose( [ SimplifySourceAndRange_IsoToInputSource( mor, infinity ), > mor, > SimplifySourceAndRange_IsoFromInputRange( mor, infinity ) ] ) > ); true gap> ## Test SimplifyEndo > endo := StringsAsCategoryMorphism( obj1, "uoiea", obj1 );; gap> IsWellDefined( endo ); true gap> IsEqualForMorphismsOnMor( SimplifyEndo( endo, 0 ), endo ); true gap> IsEqualForMorphismsOnMor( SimplifyEndo( endo, 1 ), endo ); false gap> ForAny( [0,1,2,3,4], i -> IsEqualForMorphismsOnMor( SimplifySourceAndRange( endo, i ), SimplifySourceAndRange( endo, i + 1 ) ) ); false gap> ForAll( [5,6,7,8,9], i -> IsEqualForMorphismsOnMor( SimplifySourceAndRange( endo, i ), SimplifySourceAndRange( endo, i + 1 ) ) ); true gap> iota := SimplifyEndo_IsoToInputObject( endo, infinity );; gap> iota_inv := SimplifyEndo_IsoFromInputObject( endo, infinity );; gap> IsCongruentForMorphisms( PreCompose( [ iota_inv, SimplifyEndo( endo, infinity ), iota ] ), endo ); true
Homology object
gap> field := HomalgFieldOfRationals( );; gap> A := VectorSpaceObject( 1, field );; gap> B := VectorSpaceObject( 2, field );; gap> C := VectorSpaceObject( 3, field );; gap> alpha := VectorSpaceMorphism( A, HomalgMatrix( [ [ 1, 0, 0 ] ], 1, 3, field ), C );; gap> beta := VectorSpaceMorphism( C, HomalgMatrix( [ [ 1, 0 ], [ 1, 1 ], [ 1, 2 ] ], 3, 2, field ), B );; gap> IsZero( PreCompose( alpha, beta ) ); false gap> IsCongruentForMorphisms( > IdentityMorphism( HomologyObject( alpha, beta ) ), > HomologyObjectFunctorial( alpha, beta, IdentityMorphism( C ), alpha, beta ) > ); true gap> kernel_beta := KernelEmbedding( beta );; gap> K := Source( kernel_beta );; gap> IsIsomorphism( > HomologyObjectFunctorial( > MorphismFromZeroObject( K ), > MorphismIntoZeroObject( K ), > kernel_beta, > MorphismFromZeroObject( Source( beta ) ), > beta > ) > ); true gap> cokernel_alpha := CokernelProjection( alpha );; gap> Co := Range( cokernel_alpha );; gap> IsIsomorphism( > HomologyObjectFunctorial( > alpha, > MorphismIntoZeroObject( Range( alpha ) ), > cokernel_alpha, > MorphismFromZeroObject( Co ), > MorphismIntoZeroObject( Co ) > ) > ); true gap> alpha_op := Opposite( alpha );; gap> beta_op := Opposite( beta );; gap> IsCongruentForMorphisms( > IdentityMorphism( HomologyObject( beta_op, alpha_op ) ), > HomologyObjectFunctorial( beta_op, alpha_op, IdentityMorphism( Opposite( C ) ), beta_op, alpha_op ) > ); true gap> kernel_beta := KernelEmbedding( beta_op );; gap> K := Source( kernel_beta );; gap> IsIsomorphism( > HomologyObjectFunctorial( > MorphismFromZeroObject( K ), > MorphismIntoZeroObject( K ), > kernel_beta, > MorphismFromZeroObject( Source( beta_op ) ), > beta_op > ) > ); true gap> cokernel_alpha := CokernelProjection( alpha_op );; gap> Co := Range( cokernel_alpha );; gap> IsIsomorphism( > HomologyObjectFunctorial( > alpha_op, > MorphismIntoZeroObject( Range( alpha_op ) ), > cokernel_alpha, > MorphismFromZeroObject( Co ), > MorphismIntoZeroObject( Co ) > ) > ); true
Liftable
gap> field := HomalgFieldOfRationals( );; gap> V := VectorSpaceObject( 1, field );; gap> W := VectorSpaceObject( 2, field );; gap> alpha := VectorSpaceMorphism( V, HomalgMatrix( [ [ 1, -1 ] ], 1, 2, field ), W );; gap> beta := VectorSpaceMorphism( W, HomalgMatrix( [ [ 1, 2 ], [ 3, 4 ] ], 2, 2, field ), W );; gap> IsLiftable( alpha, beta ); true gap> IsLiftable( beta, alpha ); false gap> IsLiftableAlongMonomorphism( beta, alpha ); true gap> gamma := VectorSpaceMorphism( W, HomalgMatrix( [ [ 1 ], [ 1 ] ], 2, 1, field ), V );; gap> IsColiftable( beta, gamma ); true gap> IsColiftable( gamma, beta ); false gap> IsColiftableAlongEpimorphism( beta, gamma ); true
WrapperCategory
gap> LoadPackage( "LinearAlgebraForCAP", false ); true gap> Q := HomalgFieldOfRationals( ); Q gap> Qmat := MatrixCategory( Q ); Category of matrices over Q gap> Wrapper := WrapperCategory( Qmat, rec( ) ); WrapperCategory( Category of matrices over Q ) gap> mor := ZeroMorphism( ZeroObject( Wrapper ), ZeroObject( Wrapper ) );; gap> 2 * mor;; gap> BasisOfExternalHom( Source( mor ), Range( mor ) );; gap> CoefficientsOfMorphism( mor );; gap> distinguished_object := DistinguishedObjectOfHomomorphismStructure( Wrapper );; gap> object := HomomorphismStructureOnObjects( Source( mor ), Source( mor ) );; gap> HomomorphismStructureOnMorphisms( mor, mor );; gap> HomomorphismStructureOnMorphismsWithGivenObjects( object, mor, mor, object );; gap> iota := InterpretMorphismAsMorphismFromDistinguishedObjectToHomomorphismStructure( mor );; gap> InterpretMorphismAsMorphismFromDistinguishedObjectToHomomorphismStructureWithGivenObjects( distinguished_object, mor, object );; gap> beta := InterpretMorphismFromDistinguishedObjectToHomomorphismStructureAsMorphism( Source( mor ), Range( mor ), iota );; gap> IsCongruentForMorphisms( mor, beta ); true gap> Wrapper2 := WrapperCategory( Qmat, rec( wrap_range_of_hom_structure := true ) ); WrapperCategory( Category of matrices over Q ) gap> mor := ZeroMorphism( ZeroObject( Wrapper2 ), ZeroObject( Wrapper2 ) );; gap> distinguished_object := DistinguishedObjectOfHomomorphismStructure( Wrapper2 );; gap> object := HomomorphismStructureOnObjects( Source( mor ), Source( mor ) );; gap> HomomorphismStructureOnMorphisms( mor, mor );; gap> HomomorphismStructureOnMorphismsWithGivenObjects( object, mor, mor, object );; gap> iota := InterpretMorphismAsMorphismFromDistinguishedObjectToHomomorphismStructure( mor );; gap> InterpretMorphismAsMorphismFromDistinguishedObjectToHomomorphismStructureWithGivenObjects( distinguished_object, mor, object );; gap> beta := InterpretMorphismFromDistinguishedObjectToHomomorphismStructureAsMorphism( Source( mor ), Range( mor ), iota );; gap> IsCongruentForMorphisms( mor, beta ); true
gap> LoadPackage( "LinearAlgebraForCAP" ); true gap> LoadPackage( "GeneralizedMorphismsForCAP" ); true gap> old_generalized_morphism_standard := CAP_INTERNAL!.generalized_morphism_standard;; gap> SwitchGeneralizedMorphismStandard( "cospan" ); gap> Q := HomalgFieldOfRationals( ); Q gap> id := HomalgIdentityMatrix( 8, Q ); <An unevaluated 8 x 8 identity matrix over an internal ring> gap> a := CertainColumns( CertainRows( id, [ 1, 2, 3 ] ), [ 2, 3, 4, 5 ] ); <An unevaluated non-zero 3 x 4 matrix over an internal ring> gap> b := CertainColumns( CertainRows( id, [ 1, 2, 3, 4 ] ), [ 2, 3, 4, 5, 6 ] ); <An unevaluated non-zero 4 x 5 matrix over an internal ring> gap> c := CertainColumns( CertainRows( id, [ 1, 2, 3, 4, 5 ] ), [ 3, 4, 5, 6, 7, 8 ] ); <An unevaluated non-zero 5 x 6 matrix over an internal ring> gap> IsZero( a * b ); false gap> IsZero( b * c ); false gap> IsZero( a * b * c ); true gap> Qmat := MatrixCategory( Q ); Category of matrices over Q gap> Wrapper := WrapperCategory( Qmat, rec( ) ); WrapperCategory( Category of matrices over Q ) gap> a := a / Wrapper; <A morphism in WrapperCategory( Category of matrices over Q )> gap> b := b / Wrapper; <A morphism in WrapperCategory( Category of matrices over Q )> gap> c := c / Wrapper; <A morphism in WrapperCategory( Category of matrices over Q )> gap> d := CokernelProjection( a ); <An epimorphism in WrapperCategory( Category of matrices over Q )> gap> e := CokernelColift( a, PreCompose( b, c ) ); <A morphism in WrapperCategory( Category of matrices over Q )> gap> f := KernelEmbedding( e ); <A monomorphism in WrapperCategory( Category of matrices over Q )> gap> g := KernelEmbedding( c ); <A monomorphism in WrapperCategory( Category of matrices over Q )> gap> h := KernelLift( c, PreCompose( a, b ) ); <A morphism in WrapperCategory( Category of matrices over Q )> gap> i := CokernelProjection( h ); <An epi morphism in WrapperCategory( Category of matrices over Q )> gap> ff := AsGeneralizedMorphism( f ); <A morphism in Generalized morphism category of WrapperCategory( Category of matrices over Q ) by cospan> gap> dd := AsGeneralizedMorphism( d ); <A morphism in Generalized morphism category of WrapperCategory( Category of matrices over Q ) by cospan> gap> bb := AsGeneralizedMorphism( b ); <A morphism in Generalized morphism category of WrapperCategory( Category of matrices over Q ) by cospan> gap> gg := AsGeneralizedMorphism( g ); <A morphism in Generalized morphism category of WrapperCategory( Category of matrices over Q ) by cospan> gap> ii := AsGeneralizedMorphism( i ); <A morphism in Generalized morphism category of WrapperCategory( Category of matrices over Q ) by cospan> gap> ss := PreCompose( [ ff, PseudoInverse( dd ), bb, PseudoInverse( gg ), ii ] ); <A morphism in Generalized morphism category of WrapperCategory( Category of matrices over Q ) by cospan> gap> s := HonestRepresentative( ss ); <A morphism in WrapperCategory( Category of matrices over Q )> gap> j := KernelObjectFunctorial( b, d, e ); <A morphism in WrapperCategory( Category of matrices over Q )> gap> k := CokernelObjectFunctorial( h, g, b ); <A morphism in WrapperCategory( Category of matrices over Q )> gap> HK := HomologyObject( j, s ); <An object in WrapperCategory( Category of matrices over Q )> gap> HC := HomologyObject( s, k ); <An object in WrapperCategory( Category of matrices over Q )> gap> SwitchGeneralizedMorphismStandard( old_generalized_morphism_standard );
Monoidal Categories
gap> ZZ := HomalgRingOfIntegers();; gap> Ml := AsLeftPresentation( HomalgMatrix( [ [ 2 ] ], 1, 1, ZZ ) ); <An object in Category of left presentations of Z> gap> Nl := AsLeftPresentation( HomalgMatrix( [ [ 3 ] ], 1, 1, ZZ ) ); <An object in Category of left presentations of Z> gap> Tl := TensorProductOnObjects( Ml, Nl ); <An object in Category of left presentations of Z> gap> Display( UnderlyingMatrix( Tl ) ); [ [ 3 ], [ 2 ] ] gap> IsZeroForObjects( Tl ); true gap> Bl := Braiding( DirectSum( Ml, Nl ), DirectSum( Ml, Ml ) ); <A morphism in Category of left presentations of Z> gap> Display( UnderlyingMatrix( Bl ) ); [ [ 1, 0, 0, 0 ], [ 0, 0, 1, 0 ], [ 0, 1, 0, 0 ], [ 0, 0, 0, 1 ] ] gap> IsWellDefined( Bl ); true gap> Ul := TensorUnit( CapCategory( Ml ) ); <An object in Category of left presentations of Z> gap> IntHoml := InternalHomOnObjects( DirectSum( Ml, Ul ), Nl ); <An object in Category of left presentations of Z> gap> Display( UnderlyingMatrix( IntHoml ) ); [ [ -2, -1 ], [ 1, -1 ] ] gap> generator_l1 := StandardGeneratorMorphism( IntHoml, 1 ); <A morphism in Category of left presentations of Z> gap> morphism_l1 := LambdaElimination( DirectSum( Ml, Ul ), Nl, generator_l1 ); <A morphism in Category of left presentations of Z> gap> Display( UnderlyingMatrix( morphism_l1 ) ); [ [ 0 ], [ 2 ] ] gap> generator_l2 := StandardGeneratorMorphism( IntHoml, 2 ); <A morphism in Category of left presentations of Z> gap> morphism_l2 := LambdaElimination( DirectSum( Ml, Ul ), Nl, generator_l2 ); <A morphism in Category of left presentations of Z> gap> Display( UnderlyingMatrix( morphism_l2 ) ); [ [ 0 ], [ 2 ] ] gap> IsEqualForMorphisms( LambdaIntroduction( morphism_l1 ), generator_l1 ); false gap> IsCongruentForMorphisms( LambdaIntroduction( morphism_l1 ), generator_l1 ); true gap> IsEqualForMorphisms( LambdaIntroduction( morphism_l2 ), generator_l2 ); false gap> IsCongruentForMorphisms( LambdaIntroduction( morphism_l2 ), generator_l2 ); true gap> Mr := AsRightPresentation( HomalgMatrix( [ [ 2 ] ], 1, 1, ZZ ) ); <An object in Category of right presentations of Z> gap> Nr := AsRightPresentation( HomalgMatrix( [ [ 3 ] ], 1, 1, ZZ ) ); <An object in Category of right presentations of Z> gap> Tr := TensorProductOnObjects( Mr, Nr ); <An object in Category of right presentations of Z> gap> Display( UnderlyingMatrix( Tr ) ); [ [ 3, 2 ] ] gap> IsZeroForObjects( Tr ); true gap> Br := Braiding( DirectSum( Mr, Nr ), DirectSum( Mr, Mr ) ); <A morphism in Category of right presentations of Z> gap> Display( UnderlyingMatrix( Br ) ); [ [ 1, 0, 0, 0 ], [ 0, 0, 1, 0 ], [ 0, 1, 0, 0 ], [ 0, 0, 0, 1 ] ] gap> IsWellDefined( Br ); true gap> Ur := TensorUnit( CapCategory( Mr ) ); <An object in Category of right presentations of Z> gap> IntHomr := InternalHomOnObjects( DirectSum( Mr, Ur ), Nr ); <An object in Category of right presentations of Z> gap> Display( UnderlyingMatrix( IntHomr ) ); [ [ -2, 1 ], [ -1, -1 ] ] gap> generator_r1 := StandardGeneratorMorphism( IntHomr, 1 ); <A morphism in Category of right presentations of Z> gap> morphism_r1 := LambdaElimination( DirectSum( Mr, Ur ), Nr, generator_r1 ); <A morphism in Category of right presentations of Z> gap> Display( UnderlyingMatrix( morphism_r1 ) ); [ [ 0, 2 ] ] gap> generator_r2 := StandardGeneratorMorphism( IntHoml, 2 ); <A morphism in Category of left presentations of Z> gap> morphism_r2 := LambdaElimination( DirectSum( Ml, Ul ), Nl, generator_r2 ); <A morphism in Category of left presentations of Z> gap> Display( UnderlyingMatrix( morphism_r2 ) ); [ [ 0 ], [ 2 ] ] gap> IsEqualForMorphisms( LambdaIntroduction( morphism_r1 ), generator_r1 ); false gap> IsCongruentForMorphisms( LambdaIntroduction( morphism_r1 ), generator_r1 ); true gap> IsEqualForMorphisms( LambdaIntroduction( morphism_r2 ), generator_r2 ); false gap> IsCongruentForMorphisms( LambdaIntroduction( morphism_r2 ), generator_r2 ); true
MorphismFromSourceToPushout and MorphismFromFiberProductToSink
gap> field := HomalgFieldOfRationals( );; gap> A := VectorSpaceObject( 3, field );; gap> B := VectorSpaceObject( 2, field );; gap> alpha := VectorSpaceMorphism( B, HomalgMatrix( [ [ 1, -1, 1 ], [ 1, 1, 1 ] ], 2, 3, field ), A );; gap> beta := VectorSpaceMorphism( B, HomalgMatrix( [ [ 1, 2, 1 ], [ 2, 1, 1 ] ], 2, 3, field ), A );; gap> m := MorphismFromFiberProductToSink( [ alpha, beta ] );; gap> IsCongruentForMorphisms( > m, > PreCompose( ProjectionInFactorOfFiberProduct( [ alpha, beta ], 1 ), alpha ) > ); true gap> IsCongruentForMorphisms( > m, > PreCompose( ProjectionInFactorOfFiberProduct( [ alpha, beta ], 2 ), beta ) > ); true gap> IsCongruentForMorphisms( > MorphismFromKernelObjectToSink( alpha ), > PreCompose( KernelEmbedding( alpha ), alpha ) > ); true gap> alpha_p := DualOnMorphisms( alpha );; gap> beta_p := DualOnMorphisms( beta );; gap> m_p := MorphismFromSourceToPushout( [ alpha_p, beta_p ] );; gap> IsCongruentForMorphisms( > m_p, > PreCompose( alpha_p, InjectionOfCofactorOfPushout( [ alpha_p, beta_p ], 1 ) ) > ); true gap> IsCongruentForMorphisms( > m_p, > PreCompose( beta_p, InjectionOfCofactorOfPushout( [ alpha_p, beta_p ], 2 ) ) > ); true gap> IsCongruentForMorphisms( > MorphismFromSourceToCokernelObject( alpha_p ), > PreCompose( alpha_p, CokernelProjection( alpha_p ) ) > ); true
Opposite category
gap> QQ := HomalgFieldOfRationals();; gap> vec := MatrixCategory( QQ );; gap> op := Opposite( vec );; gap> ListKnownCategoricalProperties( op ); [ "IsAbCategory", "IsAbelianCategory", "IsAbelianCategoryWithEnoughInjectives", "IsAbelianCategoryWithEnoughProjectives", "IsAdditiveCategory", "IsBraidedMonoidalCategory", "IsClosedMonoidalCategory", "IsCoclosedMonoidalCategory", "IsEnrichedOverCommutativeRegularSemigroup", "IsLinearCategoryOverCommutativeRing", "IsMonoidalCategory", "IsPreAbelianCategory", "IsRigidSymmetricClosedMonoidalCategory", "IsRigidSymmetricCoclosedMonoidalCategory", "IsSkeletalCategory", "IsStrictMonoidalCategory", "IsSymmetricClosedMonoidalCategory", "IsSymmetricCoclosedMonoidalCategory", "IsSymmetricMonoidalCategory" ] gap> V1 := Opposite( TensorUnit( vec ) );; gap> V2 := DirectSum( V1, V1 );; gap> V3 := DirectSum( V1, V2 );; gap> V4 := DirectSum( V1, V3 );; gap> V5 := DirectSum( V1, V4 );; gap> alpha13 := InjectionOfCofactorOfDirectSum( [ V1, V2 ], 1 );; gap> alpha14 := InjectionOfCofactorOfDirectSum( [ V1, V2, V1 ], 3 );; gap> alpha15 := InjectionOfCofactorOfDirectSum( [ V2, V1, V2 ], 2 );; gap> alpha23 := InjectionOfCofactorOfDirectSum( [ V2, V1 ], 1 );; gap> alpha24 := InjectionOfCofactorOfDirectSum( [ V1, V2, V1 ], 2 );; gap> alpha25 := InjectionOfCofactorOfDirectSum( [ V2, V2, V1 ], 1 );; gap> mat := [ > [ alpha13, alpha14, alpha15 ], > [ alpha23, alpha24, alpha25 ] > ];; gap> mor := MorphismBetweenDirectSums( mat );; gap> IsWellDefined( mor ); true gap> IsWellDefined( Opposite( mor ) ); true gap> IsOne( UniversalMorphismFromImage( mor, [ CoastrictionToImage( mor ), ImageEmbedding( mor ) ] ) ); true
Generalized Morphisms Category
gap> vecspaces := CreateCapCategory( "VectorSpacesForGeneralizedMorphismsTest" ); VectorSpacesForGeneralizedMorphismsTest gap> ReadPackage( "CAP", "examples/VectorSpacesAllMethods.g" ); true gap> LoadPackage( "GeneralizedMorphismsForCAP" ); true gap> B := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> C := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> B_1 := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> C_1 := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> c1_source_aid := VectorSpaceMorphism( B_1, [ [ 1, 0 ] ], B ); A rational vector space homomorphism with matrix: [ [ 1, 0 ] ] gap> SetIsSubobject( c1_source_aid, true ); gap> c1_range_aid := VectorSpaceMorphism( C, [ [ 1, 0 ], [ 0, 1 ], [ 0, 0 ] ], C_1 ); A rational vector space homomorphism with matrix: [ [ 1, 0 ], [ 0, 1 ], [ 0, 0 ] ] gap> SetIsFactorobject( c1_range_aid, true ); gap> c1_associated := VectorSpaceMorphism( B_1, [ [ 1, 1 ] ], C_1 ); A rational vector space homomorphism with matrix: [ [ 1, 1 ] ] gap> c1 := GeneralizedMorphism( c1_source_aid, c1_associated, c1_range_aid ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> B_2 := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> C_2 := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> c2_source_aid := VectorSpaceMorphism( B_2, [ [ 2, 0 ] ], B ); A rational vector space homomorphism with matrix: [ [ 2, 0 ] ] gap> SetIsSubobject( c2_source_aid, true ); gap> c2_range_aid := VectorSpaceMorphism( C, [ [ 3, 0 ], [ 0, 3 ], [ 0, 0 ] ], C_2 ); A rational vector space homomorphism with matrix: [ [ 3, 0 ], [ 0, 3 ], [ 0, 0 ] ] gap> SetIsFactorobject( c2_range_aid, true ); gap> c2_associated := VectorSpaceMorphism( B_2, [ [ 6, 6 ] ], C_2 ); A rational vector space homomorphism with matrix: [ [ 6, 6 ] ] gap> c2 := GeneralizedMorphism( c2_source_aid, c2_associated, c2_range_aid ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> IsCongruentForMorphisms( c1, c2 ); true gap> IsCongruentForMorphisms( c1, c1 ); true gap> c3_associated := VectorSpaceMorphism( B_1, [ [ 2, 2 ] ], C_1 ); A rational vector space homomorphism with matrix: [ [ 2, 2 ] ] gap> c3 := GeneralizedMorphism( c1_source_aid, c3_associated, c1_range_aid ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> IsCongruentForMorphisms( c1, c3 ); false gap> IsCongruentForMorphisms( c2, c3 ); false gap> c1 + c2; <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> Arrow( c1 + c2 ); A rational vector space homomorphism with matrix: [ [ 12, 12 ] ]
First composition test:
gap> vecspaces := CreateCapCategory( "VectorSpacesForGeneralizedMorphismsTest" ); VectorSpacesForGeneralizedMorphismsTest gap> ReadPackage( "CAP", "examples/VectorSpacesAllMethods.g" ); true gap> A := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> B := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> C := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> phi_tilde_associated := VectorSpaceMorphism( A, [ [ 1, 2, 0 ] ], C ); A rational vector space homomorphism with matrix: [ [ 1, 2, 0 ] ] gap> phi_tilde_source_aid := VectorSpaceMorphism( A, [ [ 1, 2 ] ], B ); A rational vector space homomorphism with matrix: [ [ 1, 2 ] ] gap> phi_tilde := GeneralizedMorphismWithSourceAid( phi_tilde_source_aid, phi_tilde_associated ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> psi_tilde_associated := IdentityMorphism( B ); A rational vector space homomorphism with matrix: [ [ 1, 0 ], [ 0, 1 ] ] gap> psi_tilde_source_aid := VectorSpaceMorphism( B, [ [ 1, 0, 0 ], [ 0, 1, 0 ] ], C ); A rational vector space homomorphism with matrix: [ [ 1, 0, 0 ], [ 0, 1, 0 ] ] gap> psi_tilde := GeneralizedMorphismWithSourceAid( psi_tilde_source_aid, psi_tilde_associated ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> composition := PreCompose( phi_tilde, psi_tilde ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> Arrow( composition ); A rational vector space homomorphism with matrix: [ [ 1/2, 1 ] ] gap> SourceAid( composition ); A rational vector space homomorphism with matrix: [ [ 1/2, 1 ] ] gap> RangeAid( composition ); A rational vector space homomorphism with matrix: [ [ 1, 0 ], [ 0, 1 ] ]
Second composition test
gap> vecspaces := CreateCapCategory( "VectorSpacesForGeneralizedMorphismsTest" ); VectorSpacesForGeneralizedMorphismsTest gap> ReadPackage( "CAP", "examples/VectorSpacesAllMethods.g" ); true gap> A := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> B := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> C := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> phi2_tilde_associated := VectorSpaceMorphism( A, [ [ 1, 5 ] ], B ); A rational vector space homomorphism with matrix: [ [ 1, 5 ] ] gap> phi2_tilde_range_aid := VectorSpaceMorphism( C, [ [ 1, 0 ], [ 0, 1 ], [ 1, 1 ] ], B ); A rational vector space homomorphism with matrix: [ [ 1, 0 ], [ 0, 1 ], [ 1, 1 ] ] gap> phi2_tilde := GeneralizedMorphismWithRangeAid( phi2_tilde_associated, phi2_tilde_range_aid ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> psi2_tilde_associated := VectorSpaceMorphism( C, [ [ 1 ], [ 3 ], [ 4 ] ], A ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 3 ], [ 4 ] ] gap> psi2_tilde_range_aid := VectorSpaceMorphism( B, [ [ 1 ], [ 1 ] ], A ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 1 ] ] gap> psi2_tilde := GeneralizedMorphismWithRangeAid( psi2_tilde_associated, psi2_tilde_range_aid ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> composition2 := PreCompose( phi2_tilde, psi2_tilde ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> Arrow( composition2 ); A rational vector space homomorphism with matrix: [ [ 16 ] ] gap> RangeAid( composition2 ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 1 ] ] gap> SourceAid( composition2 ); A rational vector space homomorphism with matrix: [ [ 1 ] ]
Third composition test
gap> vecspaces := CreateCapCategory( "VectorSpacesForGeneralizedMorphismsTest" ); VectorSpacesForGeneralizedMorphismsTest gap> ReadPackage( "CAP", "examples/VectorSpacesAllMethods.g" ); true gap> A := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> Asub := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> B := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> Bfac := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> Bsub := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> C := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> Cfac := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> Asub_into_A := VectorSpaceMorphism( Asub, [ [ 1, 0, 0 ], [ 0, 1, 0 ] ], A ); A rational vector space homomorphism with matrix: [ [ 1, 0, 0 ], [ 0, 1, 0 ] ] gap> Asub_to_Bfac := VectorSpaceMorphism( Asub, [ [ 1 ], [ 1 ] ], Bfac ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 1 ] ] gap> B_onto_Bfac := VectorSpaceMorphism( B, [ [ 1 ], [ 1 ], [ 1 ] ], Bfac ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 1 ], [ 1 ] ] gap> Bsub_into_B := VectorSpaceMorphism( Bsub, [ [ 2, 2, 0 ], [ 0, 2, 2 ] ], B ); A rational vector space homomorphism with matrix: [ [ 2, 2, 0 ], [ 0, 2, 2 ] ] gap> Bsub_to_Cfac := VectorSpaceMorphism( Bsub, [ [ 3 ], [ 0 ] ], Cfac ); A rational vector space homomorphism with matrix: [ [ 3 ], [ 0 ] ] gap> C_onto_Cfac := VectorSpaceMorphism( C, [ [ 1 ], [ 2 ], [ 3 ] ], Cfac ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 2 ], [ 3 ] ] gap> generalized_morphism1 := GeneralizedMorphism( Asub_into_A, Asub_to_Bfac, B_onto_Bfac ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> generalized_morphism2 := GeneralizedMorphism( Bsub_into_B, Bsub_to_Cfac, C_onto_Cfac ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> IsWellDefined( generalized_morphism1 ); true gap> IsWellDefined( generalized_morphism2 ); true gap> p := PreCompose( generalized_morphism1, generalized_morphism2 ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> SourceAid( p ); A rational vector space homomorphism with matrix: [ [ -1, 1, 0 ], [ 1, 0, 0 ] ] gap> Arrow( p ); A rational vector space homomorphism with matrix: (an empty 2 x 0 matrix) gap> RangeAid( p ); A rational vector space homomorphism with matrix: (an empty 3 x 0 matrix) gap> A := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> Asub := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> B := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> Bfac := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> Bsub := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> C := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> Cfac := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> Asub_into_A := VectorSpaceMorphism( Asub, [ [ 1, 0, 0 ], [ 0, 1, 0 ] ], A ); A rational vector space homomorphism with matrix: [ [ 1, 0, 0 ], [ 0, 1, 0 ] ] gap> Asub_to_Bfac := VectorSpaceMorphism( Asub, [ [ 1 ], [ 1 ] ], Bfac ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 1 ] ] gap> B_onto_Bfac := VectorSpaceMorphism( B, [ [ 1 ], [ 1 ], [ 1 ] ], Bfac ); A rational vector space homomorphism with matrix: [ [ 1 ], [ 1 ], [ 1 ] ] gap> Bsub_into_B := VectorSpaceMorphism( Bsub, [ [ 2, 2, 0 ], [ 0, 2, 2 ] ], B ); A rational vector space homomorphism with matrix: [ [ 2, 2, 0 ], [ 0, 2, 2 ] ] gap> Bsub_to_Cfac := VectorSpaceMorphism( Bsub, [ [ 3, 3 ], [ 0, 0 ] ], Cfac ); A rational vector space homomorphism with matrix: [ [ 3, 3 ], [ 0, 0 ] ] gap> C_onto_Cfac := VectorSpaceMorphism( C, [ [ 1, 0 ], [ 0, 2 ], [ 3, 3 ] ], Cfac ); A rational vector space homomorphism with matrix: [ [ 1, 0 ], [ 0, 2 ], [ 3, 3 ] ] gap> generalized_morphism1 := GeneralizedMorphism( Asub_into_A, Asub_to_Bfac, B_onto_Bfac ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> generalized_morphism2 := GeneralizedMorphism( Bsub_into_B, Bsub_to_Cfac, C_onto_Cfac ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> IsWellDefined( generalized_morphism1 ); true gap> IsWellDefined( generalized_morphism2 ); true gap> p := PreCompose( generalized_morphism1, generalized_morphism2 ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> SourceAid( p ); A rational vector space homomorphism with matrix: [ [ -1, 1, 0 ], [ 1, 0, 0 ] ] gap> Arrow( p ); A rational vector space homomorphism with matrix: [ [ 0 ], [ 0 ] ] gap> RangeAid( p ); A rational vector space homomorphism with matrix: [ [ -1 ], [ 2 ], [ 0 ] ]
Honest representative test
gap> vecspaces := CreateCapCategory( "VectorSpacesForGeneralizedMorphismsTest" ); VectorSpacesForGeneralizedMorphismsTest gap> ReadPackage( "CAP", "examples/VectorSpacesAllMethods.g" ); true gap> A := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> B := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> phi_tilde_source_aid := VectorSpaceMorphism( A, [ [ 2 ] ], A ); A rational vector space homomorphism with matrix: [ [ 2 ] ] gap> phi_tilde_associated := VectorSpaceMorphism( A, [ [ 1, 1 ] ], B ); A rational vector space homomorphism with matrix: [ [ 1, 1 ] ] gap> phi_tilde_range_aid := VectorSpaceMorphism( B, [ [ 1, 2 ], [ 3, 4 ] ], B ); A rational vector space homomorphism with matrix: [ [ 1, 2 ], [ 3, 4 ] ] gap> phi_tilde := GeneralizedMorphism( phi_tilde_source_aid, phi_tilde_associated, phi_tilde_range_aid ); <A morphism in Generalized morphism category of VectorSpacesForGeneralizedMorphismsTest> gap> HonestRepresentative( phi_tilde ); A rational vector space homomorphism with matrix: [ [ -1/4, 1/4 ] ] gap> IsWellDefined( phi_tilde ); true gap> IsWellDefined( psi_tilde ); true
IsWellDefined
gap> vecspaces := CreateCapCategory( "VectorSpacesForIsWellDefinedTest" ); VectorSpacesForIsWellDefinedTest gap> ReadPackage( "CAP", "examples/VectorSpacesAllMethods.g" ); true gap> LoadPackage( "GeneralizedMorphismsForCAP" ); true gap> A := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> B := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> alpha := VectorSpaceMorphism( A, [ [ 1, 2 ] ], B ); A rational vector space homomorphism with matrix: [ [ 1, 2 ] ] gap> g := GeneralizedMorphism( alpha, alpha, alpha ); <A morphism in Generalized morphism category of VectorSpacesForIsWellDefinedTest> gap> IsWellDefined( alpha ); true gap> IsWellDefined( g ); true gap> IsEqualForObjects( A, B ); false
Kernel
gap> vecspaces := CreateCapCategory( "VectorSpaces01" ); VectorSpaces01 gap> ReadPackage( "CAP", "examples/VectorSpacesAddKernel01.g" ); true gap> V := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> W := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> alpha := VectorSpaceMorphism( V, [ [ 1, 1, 1 ], [ -1, -1, -1 ] ], W ); A rational vector space homomorphism with matrix: [ [ 1, 1, 1 ], [ -1, -1, -1 ] ] gap> k := KernelObject( alpha ); <A rational vector space of dimension 1> gap> T := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> tau := VectorSpaceMorphism( T, [ [ 2, 2 ], [ 2, 2 ] ], V ); A rational vector space homomorphism with matrix: [ [ 2, 2 ], [ 2, 2 ] ] gap> k_lift := KernelLift( alpha, tau ); A rational vector space homomorphism with matrix: [ [ 2 ], [ 2 ] ] gap> HasKernelEmbedding( alpha ); false gap> KernelEmbedding( alpha ); A rational vector space homomorphism with matrix: [ [ 1, 1 ] ]
gap> vecspaces := CreateCapCategory( "VectorSpaces02" ); VectorSpaces02 gap> ReadPackage( "CAP", "examples/VectorSpacesAddKernel02.g" ); true gap> V := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> W := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> alpha := VectorSpaceMorphism( V, [ [ 1, 1, 1 ], [ -1, -1, -1 ] ], W ); A rational vector space homomorphism with matrix: [ [ 1, 1, 1 ], [ -1, -1, -1 ] ] gap> k := KernelObject( alpha ); <A rational vector space of dimension 1> gap> T := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> tau := VectorSpaceMorphism( T, [ [ 2, 2 ], [ 2, 2 ] ], V ); A rational vector space homomorphism with matrix: [ [ 2, 2 ], [ 2, 2 ] ] gap> k_lift := KernelLift( alpha, tau ); A rational vector space homomorphism with matrix: [ [ 2 ], [ 2 ] ] gap> HasKernelEmbedding( alpha ); false
gap> vecspaces := CreateCapCategory( "VectorSpaces03" ); VectorSpaces03 gap> ReadPackage( "CAP", "examples/VectorSpacesAddKernel03.g" ); true gap> V := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> W := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> alpha := VectorSpaceMorphism( V, [ [ 1, 1, 1 ], [ -1, -1, -1 ] ], W ); A rational vector space homomorphism with matrix: [ [ 1, 1, 1 ], [ -1, -1, -1 ] ] gap> k := KernelObject( alpha ); <A rational vector space of dimension 1> gap> k_emb := KernelEmbedding( alpha ); A rational vector space homomorphism with matrix: [ [ 1, 1 ] ] gap> IsIdenticalObj( Source( k_emb ), k ); true gap> V := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> W := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> beta := VectorSpaceMorphism( V, [ [ 1, 1, 1 ], [ -1, -1, -1 ] ], W ); A rational vector space homomorphism with matrix: [ [ 1, 1, 1 ], [ -1, -1, -1 ] ] gap> k_emb := KernelEmbedding( beta ); A rational vector space homomorphism with matrix: [ [ 1, 1 ] ] gap> IsIdenticalObj( Source( k_emb ), KernelObject( beta ) ); true
FiberProduct
gap> vecspaces := CreateCapCategory( "VectorSpacesForFiberProductTest" ); VectorSpacesForFiberProductTest gap> ReadPackage( "CAP", "examples/VectorSpacesAllMethods.g" ); true gap> A := QVectorSpace( 1 ); <A rational vector space of dimension 1> gap> B := QVectorSpace( 2 ); <A rational vector space of dimension 2> gap> C := QVectorSpace( 3 ); <A rational vector space of dimension 3> gap> AtoC := VectorSpaceMorphism( A, [ [ 1, 2, 0 ] ], C ); A rational vector space homomorphism with matrix: [ [ 1, 2, 0 ] ] gap> BtoC := VectorSpaceMorphism( B, [ [ 1, 0, 0 ], [ 0, 1, 0 ] ], C ); A rational vector space homomorphism with matrix: [ [ 1, 0, 0 ], [ 0, 1, 0 ] ] gap> P := FiberProduct( AtoC, BtoC ); <A rational vector space of dimension 1> gap> p1 := ProjectionInFactorOfFiberProduct( [ AtoC, BtoC ], 1 ); A rational vector space homomorphism with matrix: [ [ 1/2 ] ] gap> p2 := ProjectionInFactorOfFiberProduct( [ AtoC, BtoC ], 2 ); A rational vector space homomorphism with matrix: [ [ 1/2, 1 ] ]