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14 Examples on graded rows and columns
 14.1 Freyd category of graded rows
 14.2 Freyd category of graded columns

14 Examples on graded rows and columns

14.1 Freyd category of graded rows

gap> Q := HomalgFieldOfRationalsInSingular();;
gap> S := GradedRing( Q * "x_1, x_2" );;
gap> SetWeightsOfIndeterminates( S, [[1],[1]] );;
gap> Module := AsFreydCategoryObject( GradedRow( [[[1],1]], S ) );
<A projective object in Category of f.p. graded left modules over Q[x_1,x_2] (with weights [ 1, 1 ])>
gap> IsFpGradedLeftOrRightModulesObject( Module );
true
gap> mor := AsFreydCategoryMorphism( IdentityMorphism( GradedRow( [[[1],1]], S ) ) );
<A morphism in Category of f.p. graded left modules over Q[x_1,x_2] (with weights [ 1, 1 ])>
gap> IsFpGradedLeftOrRightModulesMorphism( mor );
true
gap> Q := HomalgFieldOfRationalsInSingular();
Q
gap> S := GradedRing( Q * "x_1, x_2, x_3, x_4" );
Q[x_1,x_2,x_3,x_4]
(weights: yet unset)
gap> SetWeightsOfIndeterminates( S, [[1,0],[1,0],[0,1],[0,1]] );

gap> cat := CategoryOfGradedRows( S );
Category of graded rows over Q[x_1,x_2,x_3,x_4] 
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
gap> obj1 := GradedRow( [ [[1,1],1] ], S );
<A graded row of rank 1>
gap> obj2 := GradedRow( [ [[1,1],2] ], S );
<A graded row of rank 2>
gap> gamma := GradedRowOrColumnMorphism( obj2, 
>                        HomalgMatrix( [ [ 1, 1 ], [ 1, 1 ] ], 2, 2, S ), obj2 );
<A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> freyd := FreydCategory( cat );
Category of f.p. graded left modules over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
gap> IsAbelianCategory( freyd );
true
gap> obj_gamma := FreydCategoryObject( gamma );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsFpGradedLeftOrRightModulesObject( obj_gamma );
true
gap> f := FreydCategoryMorphism( obj_gamma, gamma, obj_gamma );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsFpGradedLeftOrRightModulesMorphism( f );
true
gap> witness := MorphismWitness( f );
<A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( witness );
A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
2,0,
2,0
(over a graded ring)

Range:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]
gap> g := FreydCategoryMorphism( obj_gamma, 
>                                    ZeroMorphism( obj2, obj2 ), obj_gamma );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsCongruentForMorphisms( f, g );
true
gap> c := PreCompose( f, f );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( c );
A morphism in Category of f.p. graded left modules over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) )

--------------------------------

Source:
A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
1,1,
1,1
(over a graded ring)

Range:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

--------------------------------

Morphism datum:
A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
2,2,
2,2 
(over a graded ring)

Range:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

--------------------------------

Range:
A morphism in Category of graded row over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
1,1,
1,1
(over a graded ring)

Range:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

--------------------------------
gap> s := g + g;
<A morphism in Category of f.p. graded left modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> a := GradedRowOrColumnMorphism( obj1, 
>                                  HomalgMatrix( [ [ 2 ] ], 1, 1, S ), obj1 );
<A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( a );
A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]

Matrix:
2
(over a graded ring)

Range:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]
gap> Z2 := FreydCategoryObject( a );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( Z2 );
An object in Freyd( Category of graded rows over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) )

Relation morphism:
A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]

Matrix:
2
(over a graded ring)

Range:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]
gap> id := IdentityMorphism( Z2 );
<An identity morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> z := id + id + id;
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> d := DirectSumFunctorial( [ z, z, z ] );
<A morphism in Category of f.p. graded left modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> pr2 := ProjectionInFactorOfDirectSum( [ Z2, Z2, Z2 ], 2 );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> pr3 := ProjectionInFactorOfDirectSum( [ Z2, Z2, Z2 ], 3 );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> uni := UniversalMorphismIntoDirectSum( [ pr3, pr2 ] );
<A morphism in Category of f.p. graded left modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> inj1 := InjectionOfCofactorOfDirectSum( [ Z2, Z2, Z2 ], 1 );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> inj2 := InjectionOfCofactorOfDirectSum( [ Z2, Z2, Z2 ], 2 );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> uni2 := UniversalMorphismFromDirectSum( [ inj2, inj1 ] );
<A morphism in Category of f.p. graded left modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> ZFree := AsFreydCategoryObject( obj1 );
<A projective object in Category of f.p. graded left modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( ZFree );
A projective object in Freyd( Category of graded rows over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) )

Relation morphism:
A morphism in Category of graded rows over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 0 and degrees:
[  ]

Matrix:
(an empty 0 x 1 matrix)

Range:
A graded row over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]
gap> id := IdentityMorphism( ZFree );
<An identity morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> z := id + id;
<A morphism in Category of f.p. graded left modules over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> coker_proj := CokernelProjection( z );
<An epimorphism in Category of f.p. graded left modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> cokernel_colift := CokernelColift( z, CokernelProjection( z ) );
<A morphism in Category of f.p. graded left modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> a := ZFree;
<A projective object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> b := obj_gamma;
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> c := TensorProductOnObjects( ZFree, obj_gamma );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> KaxbKxc := TensorProductOnObjects( TensorProductOnObjects( a, b ), c );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEqualForObjects( KaxbKxc, ZeroObject( freyd ) );
false
gap> tensor_product_morphism := TensorProductOnMorphisms( cokernel_colift, coker_proj );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEpimorphism( tensor_product_morphism );
true
gap> IsEqualForObjects( Source( tensor_product_morphism ), Range( tensor_product_morphism ) );
false
gap> unit := TensorUnit( freyd );
<An object in Category of f.p. graded left modules over Q[x_1,x_2,x_3,x_4] 
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEqualForObjects( TensorProductOnObjects( a, unit ), a );
true
gap> axKbxcK := TensorProductOnObjects( a, TensorProductOnObjects( b, c ) );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> ass_left_to_right := AssociatorLeftToRightWithGivenTensorProducts( KaxbKxc, a, b, c, axKbxcK );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsIsomorphism( ass_left_to_right );
true
gap> ass_right_to_left := AssociatorLeftToRightWithGivenTensorProducts( axKbxcK, a, b, c, KaxbKxc );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsMonomorphism( ass_right_to_left );
true
gap> IsEpimorphism( ass_right_to_left );
true
gap> LeftUnitor( a );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> LeftUnitorInverse( axKbxcK );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> RightUnitor( b );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> RightUnitorInverse( TensorProductOnObjects( axKbxcK, axKbxcK ) );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Braiding( axKbxcK, KaxbKxc );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> braiding := Braiding( a, b );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsWellDefined( braiding );
true
gap> hom := InternalHomOnObjects( axKbxcK, axKbxcK );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsZero( hom );
false
gap> free_mod1 := AsFreydCategoryObject( GradedRow( [ [[0,0],1] ], S ) );
<A projective object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> free_mod2 := AsFreydCategoryObject( GradedRow( [ [[1,1],1] ], S ) );
<A projective object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> hom2 := InternalHomOnObjects( free_mod1, free_mod2 );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsZero( hom2 );
false
gap> IsZero( Source( RelationMorphism( hom2 ) ) );
true
gap> Rank( Range( RelationMorphism( hom2 ) ) );
1
gap> hom3 := InternalHomOnObjects( free_mod2, free_mod1 );
<An object in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsZero( hom3 );
false
gap> InternalHomOnMorphisms( ass_left_to_right, ass_right_to_left );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> eval := ClosedMonoidalLeftEvaluationMorphism( a, b );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEpimorphism( eval );
true
gap> IsMonomorphism( eval );
true
gap> coeval := ClosedMonoidalLeftCoevaluationMorphism( a, b );
<A morphism in Category of f.p. graded left modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEpimorphism( coeval );
true
gap> IsMonomorphism( coeval );
true

14.2 Freyd category of graded columns

gap> Q := HomalgFieldOfRationalsInSingular();
Q
gap> S := GradedRing( Q * "x_1, x_2, x_3, x_4" );
Q[x_1,x_2,x_3,x_4]
(weights: yet unset)
gap> SetWeightsOfIndeterminates( S, [[1,0],[1,0],[0,1],[0,1]] );

gap> cat := CategoryOfGradedColumns( S );
Category of graded columns over Q[x_1,x_2,x_3,x_4] 
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
gap> obj1 := GradedColumn( [ [[1,1],1] ], S );
<A graded column of rank 1>
gap> obj2 := GradedColumn( [ [[1,1],2] ], S );
<A graded column of rank 2>
gap> gamma := GradedRowOrColumnMorphism( obj2, 
>                        HomalgMatrix( [ [ 1, 1 ], [ 1, 1 ] ], 2, 2, S ), obj2 );
<A morphism in Category of graded columns over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> freyd := FreydCategory( cat );
Category of f.p. graded right modules over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
gap> IsAbelianCategory( freyd );
true
gap> obj_gamma := FreydCategoryObject( gamma );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> f := FreydCategoryMorphism( obj_gamma, gamma, obj_gamma );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> witness := MorphismWitness( f );
<A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( witness );
A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
2,2,
0,0 
(over a graded ring)

Range:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]
gap> g := FreydCategoryMorphism( obj_gamma, 
>                                    ZeroMorphism( obj2, obj2 ), obj_gamma );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsCongruentForMorphisms( f, g );
true
gap> c := PreCompose( f, f );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( c );
A morphism in Category of f.p. graded right modules over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) )

--------------------------------

Source:
A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
1,1,
1,1
(over a graded ring)

Range:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

--------------------------------

Morphism datum:
A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
2,2,
2,2
(over a graded ring)

Range:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

--------------------------------

Range:
A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

Matrix:
1,1,
1,1
(over a graded ring)

Range:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])
of rank 2 and degrees:
[ [ ( 1, 1 ), 2 ] ]

--------------------------------
gap> s := g + g;
<A morphism in Category of f.p. graded right modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> a := GradedRowOrColumnMorphism( obj1, 
>                                  HomalgMatrix( [ [ 2 ] ], 1, 1, S ), obj1 );
<A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( a );
A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]

Matrix:
2
(over a graded ring)

Range:
A graded column over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]
gap> Z2 := FreydCategoryObject( a );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( Z2 );
An object in Freyd( Category of graded columns over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) )

Relation morphism:
A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]

Matrix:
2
(over a graded ring)

Range:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]
gap> id := IdentityMorphism( Z2 );
<An identity morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> z := id + id + id;
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> d := DirectSumFunctorial( [ z, z, z ] );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> pr2 := ProjectionInFactorOfDirectSum( [ Z2, Z2, Z2 ], 2 );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> pr3 := ProjectionInFactorOfDirectSum( [ Z2, Z2, Z2 ], 3 );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> uni := UniversalMorphismIntoDirectSum( [ pr3, pr2 ] );
<A morphism in Category of f.p. graded right modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> inj1 := InjectionOfCofactorOfDirectSum( [ Z2, Z2, Z2 ], 1 );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> inj2 := InjectionOfCofactorOfDirectSum( [ Z2, Z2, Z2 ], 2 );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> uni2 := UniversalMorphismFromDirectSum( [ inj2, inj1 ] );
<A morphism in Category of f.p. graded right modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> ZFree := AsFreydCategoryObject( obj1 );
<A projective object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Display( ZFree );
A projective object in Category of f.p. graded right modules over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) )

Relation morphism:
A morphism in Category of graded columns over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])

Source:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 0 and degrees:
[  ]

Matrix:
(an empty 1 x 0 matrix)

Range:
A graded column over Q[x_1,x_2,x_3,x_4] (with weights
[ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ]) of rank 1 and degrees:
[ [ ( 1, 1 ), 1 ] ]
gap> id := IdentityMorphism( ZFree );
<An identity morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> z := id + id;
<A morphism in Category of f.p. graded right modules over Q[x_1,x_2,x_3,x_4]
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> coker_proj := CokernelProjection( z );
<An epimorphism in Category of f.p. graded right modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> cokernel_colift := CokernelColift( z, CokernelProjection( z ) );
<A morphism in Category of f.p. graded right modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> a := ZFree;
<A projective object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> b := obj_gamma;
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> c := TensorProductOnObjects( a, b );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> KaxbKxc := TensorProductOnObjects( TensorProductOnObjects( a, b ), c );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEqualForObjects( KaxbKxc, ZeroObject( freyd ) );
false
gap> tensor_product_morphism := TensorProductOnMorphisms( cokernel_colift, coker_proj );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEpimorphism( tensor_product_morphism );
true
gap> IsEqualForObjects( Source( tensor_product_morphism ), Range( tensor_product_morphism ) );
false
gap> unit := TensorUnit( freyd );
<An object in Category of f.p. graded right modules over Q[x_1,x_2,x_3,x_4] 
(with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEqualForObjects( TensorProductOnObjects( a, unit ), a );
true
gap> axKbxcK := TensorProductOnObjects( a, TensorProductOnObjects( b, c ) );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> ass_left_to_right := AssociatorLeftToRightWithGivenTensorProducts( KaxbKxc, a, b, c, axKbxcK );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsIsomorphism( ass_left_to_right );
true
gap> ass_right_to_left := AssociatorLeftToRightWithGivenTensorProducts( axKbxcK, a, b, c, KaxbKxc );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsMonomorphism( ass_right_to_left );
true
gap> IsEpimorphism( ass_right_to_left );
true
gap> LeftUnitor( a );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> LeftUnitorInverse( axKbxcK );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> RightUnitor( b );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> RightUnitorInverse( TensorProductOnObjects( axKbxcK, axKbxcK ) );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> Braiding( axKbxcK, KaxbKxc );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> braiding := Braiding( a, b );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsWellDefined( braiding );
true
gap> hom := InternalHomOnObjects( axKbxcK, axKbxcK );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsZero( hom );
false
gap> free_mod1 := AsFreydCategoryObject( GradedColumn( [ [[0,0],1] ], S ) );
<A projective object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> free_mod2 := AsFreydCategoryObject( GradedColumn( [ [[1,1],1] ], S ) );
<A projective object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> hom2 := InternalHomOnObjects( free_mod1, free_mod2 );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsZero( hom2 );
false
gap> IsZero( Source( RelationMorphism( hom2 ) ) );
true
gap> Rank( Range( RelationMorphism( hom2 ) ) );
1
gap> hom3 := InternalHomOnObjects( free_mod2, free_mod1 );
<An object in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsZero( hom3 );
false
gap> InternalHomOnMorphisms( ass_left_to_right, ass_right_to_left );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> eval := ClosedMonoidalLeftEvaluationMorphism( a, b );
<A morphism in Category of f.p. graded right modules over 
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEpimorphism( eval );
true
gap> IsMonomorphism( eval );
true
gap> coeval := ClosedMonoidalLeftCoevaluationMorphism( a, b );
<A morphism in Category of f.p. graded right modules over
Q[x_1,x_2,x_3,x_4] (with weights [ [ 1, 0 ], [ 1, 0 ], [ 0, 1 ], [ 0, 1 ] ])>
gap> IsEpimorphism( coeval );
true
gap> IsMonomorphism( coeval );
true
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