‣ IsHomalgMorphism ( phi ) | ( category ) |
Returns: true
or false
This is the super GAP-category which will include the GAP-categories IsHomalgStaticMorphism
(4.1-2) and IsHomalgChainMorphism
(7.1-1). We need this GAP-category to be able to build complexes with *objects* being objects of homalg categories or again complexes. We need this GAP-category to be able to build chain morphisms with *morphisms* being morphisms of homalg categories or again chain morphisms.
CAUTION: Never let homalg morphisms (which are not endomorphisms) be multiplicative elements!!
DeclareCategory( "IsHomalgMorphism", IsHomalgStaticObjectOrMorphism and IsAdditiveElementWithInverse );
‣ IsHomalgStaticMorphism ( phi ) | ( category ) |
Returns: true
or false
This is the super GAP-category which will include the GAP-categories IsHomalgMap
, etc.
CAUTION: Never let homalg morphisms (which are not endomorphisms) be multiplicative elements!!
DeclareCategory( "IsHomalgStaticMorphism", IsHomalgMorphism );
‣ IsHomalgEndomorphism ( phi ) | ( category ) |
Returns: true
or false
This is the super GAP-category which will include the GAP-categories IsHomalgSelfMap
, IsHomalgChainEndomorphism
(7.1-2), etc. be multiplicative elements!!
DeclareCategory( "IsHomalgEndomorphism", IsHomalgMorphism and IsMultiplicativeElementWithInverse );
‣ IsMorphismOfFinitelyGeneratedObjectsRep ( phi ) | ( representation ) |
Returns: true
or false
The GAP representation of morphisms of finitley generated homalg objects.
(It is a representation of the GAP category IsHomalgMorphism
(4.1-1).)
DeclareRepresentation( "IsMorphismOfFinitelyGeneratedObjectsRep", IsHomalgMorphism, [ ] );
‣ IsStaticMorphismOfFinitelyGeneratedObjectsRep ( phi ) | ( representation ) |
Returns: true
or false
The GAP representation of static morphisms of finitley generated homalg static objects.
(It is a representation of the GAP category IsHomalgStaticMorphism
(4.1-2), which is a subrepresentation of the GAP representation IsMorphismOfFinitelyGeneratedObjectsRep
(4.1-4).)
DeclareRepresentation( "IsStaticMorphismOfFinitelyGeneratedObjectsRep", IsHomalgStaticMorphism and IsMorphismOfFinitelyGeneratedObjectsRep, [ ] );
‣ IsMorphism ( phi ) | ( property ) |
Returns: true
or false
IsMorphism
=true
means one of the following:
The property method IsMorphism
(phi) was explicitly invoked by the user and it returned true
, where prior to the invocation HasIsMorphism
(phi) was false
. The method is meant to check the integrity of the data structure at the time of it invocation. What this precisely means depends on the specific homalg-based package.
The user has explicitly SetIsMorphism
(phi, true
).
The morphism phi is output of a categorical procedure where IsMorphism
has become true
for all morphisms in the input.
The morphism phi is output of a categorical procedure which gurantees the integrity of the data structure of its output independent of its input.
‣ IsGeneralizedMorphismWithFullDomain ( phi ) | ( property ) |
Returns: true
or false
Check if phi is a generalized morphism.
‣ IsGeneralizedEpimorphism ( phi ) | ( property ) |
Returns: true
or false
Check if phi is a generalized epimorphism.
‣ IsGeneralizedMonomorphism ( phi ) | ( property ) |
Returns: true
or false
Check if phi is a generalized monomorphism.
‣ IsGeneralizedIsomorphism ( phi ) | ( property ) |
Returns: true
or false
Check if phi is a generalized isomorphism.
‣ IsOne ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is the identity morphism.
‣ IsIdempotent ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is an automorphism.
‣ IsMonomorphism ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is a monomorphism.
‣ IsEpimorphism ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is an epimorphism.
‣ IsSplitMonomorphism ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is a split monomorphism.
‣ IsSplitEpimorphism ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is a split epimorphism.
‣ IsIsomorphism ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is an isomorphism.
‣ IsAutomorphism ( phi ) | ( property ) |
Returns: true
or false
Check if the homalg morphism phi is an automorphism.
‣ Source ( phi ) | ( attribute ) |
Returns: a homalg object
The source of the homalg morphism phi.
‣ Range ( phi ) | ( attribute ) |
Returns: a homalg object
The target (range) of the homalg morphism phi.
‣ CokernelEpi ( phi ) | ( attribute ) |
Returns: a homalg morphism
The natural epimorphism from the Range
(phi) onto the Cokernel
(phi).
‣ CokernelNaturalGeneralizedIsomorphism ( phi ) | ( attribute ) |
Returns: a homalg morphism
The natural generalized isomorphism from the Cokernel
(phi) onto the Range
(phi).
‣ KernelSubobject ( phi ) | ( attribute ) |
Returns: a homalg subobject
This constructor returns the finitely generated kernel of the homalg morphism phi as a subobject of the homalg object Source
(phi) with generators given by the syzygies of phi.
‣ KernelEmb ( phi ) | ( attribute ) |
Returns: a homalg morphism
The natural embedding of the Kernel
(phi) into the Source
(phi).
‣ ImageSubobject ( phi ) | ( attribute ) |
Returns: a homalg subobject
This constructor returns the finitely generated image of the homalg morphism phi as a subobject of the homalg object Range
(phi) with generators given by phi applied to the generators of its source object.
‣ ImageObjectEmb ( phi ) | ( attribute ) |
Returns: a homalg morphism
The natural embedding of the ImageObject
(phi) into the Range
(phi).
‣ ImageObjectEpi ( phi ) | ( attribute ) |
Returns: a homalg morphism
The natural epimorphism from the Source
(phi) onto the ImageObject
(phi).
‣ MorphismAid ( phi ) | ( attribute ) |
Returns: a homalg morphism
The morphism aid map of a true generalized map.
(no method installed)
‣ InverseOfGeneralizedMorphismWithFullDomain ( phi ) | ( attribute ) |
Returns: a homalg morphism
The generalized inverse of the epimorphism phi (cf. [Bar09, Cor. 4.8])).
‣ DegreeOfMorphism ( phi ) | ( attribute ) |
Returns: an integer
The degree of the morphism phi between graded objects.
(no method installed)
‣ ByASmallerPresentation ( phi ) | ( method ) |
Returns: a homalg map
It invokes ByASmallerPresentation
for homalg (static) objects.
InstallMethod( ByASmallerPresentation, "for homalg morphisms", [ IsStaticMorphismOfFinitelyGeneratedObjectsRep ], function( phi ) ByASmallerPresentation( Source( phi ) ); ByASmallerPresentation( Range( phi ) ); return DecideZero( phi ); end );
This method performs side effects on its argument phi and returns it.
gap> zz := HomalgRingOfIntegers( ); Z gap> M := HomalgMatrix( "[ 2, 3, 4, 5, 6, 7 ]", 2, 3, zz ); <A 2 x 3 matrix over an internal ring> gap> M := LeftPresentation( M ); <A non-torsion left module presented by 2 relations for 3 generators> gap> N := HomalgMatrix( "[ 2, 3, 4, 5, 6, 7, 8, 9 ]", 2, 4, zz ); <A 2 x 4 matrix over an internal ring> gap> N := LeftPresentation( N ); <A non-torsion left module presented by 2 relations for 4 generators> gap> mat := HomalgMatrix( "[ \ > 1, 0, -2, -4, \ > 0, 1, 4, 7, \ > 1, 0, -2, -4 \ > ]", 3, 4, zz ); <A 3 x 4 matrix over an internal ring> gap> phi := HomalgMap( mat, M, N ); <A "homomorphism" of left modules> gap> IsMorphism( phi ); true gap> phi; <A homomorphism of left modules> gap> Display( phi ); [ [ 1, 0, -2, -4 ], [ 0, 1, 4, 7 ], [ 1, 0, -2, -4 ] ] the map is currently represented by the above 3 x 4 matrix gap> ByASmallerPresentation( phi ); <A non-zero homomorphism of left modules> gap> Display( phi ); [ [ 0, 0, 0 ], [ 1, -1, -2 ] ] the map is currently represented by the above 2 x 3 matrix gap> M; <A rank 1 left module presented by 1 relation for 2 generators> gap> Display( M ); Z/< 3 > + Z^(1 x 1) gap> N; <A rank 2 left module presented by 1 relation for 3 generators> gap> Display( N ); Z/< 4 > + Z^(1 x 2)
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