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1 Constructors
 1.1 Constructing categories
 1.2 Constructing objects
 1.3 Constructing morphisms

1 Constructors

1.1 Constructing categories

1.1-1 IsComplexesCategory
‣ IsComplexesCategory( C )( filter )

Returns: true or false

GAP-categories of the chain or cochain complexes category.

1.1-2 IsComplexesCategoryByChains
‣ IsComplexesCategoryByChains( C )( filter )

Returns: true or false

GAP-categories of the chain complexes category.

1.1-3 IsComplexesCategoryByCochains
‣ IsComplexesCategoryByCochains( C )( filter )

Returns: true or false

GAP-category of the cochain complexes category.

1.1-4 ComplexesCategoryByCochains
‣ ComplexesCategoryByCochains( A )( attribute )

Returns: a CAP category

Creates the complexes category by cochains \(\mathcal{C}^b(A)\) of an additive category \(A\).

1.1-5 ComplexesCategoryByChains
‣ ComplexesCategoryByChains( A )( attribute )

Returns: a CAP category

Creates the complexes category by chains \(\mathcal{C}^b(A)\) of an additive category \(A\).

1.1-6 UnderlyingCategory
‣ UnderlyingCategory( C )( attribute )

Returns: a CAP category

The input is a complexes category by (co)chains \(C:=\mathcal{C}^b(A)\). The outout is \(A\).

1.2 Constructing objects

1.2-1 IsChainOrCochainComplex
‣ IsChainOrCochainComplex( C )( filter )

Returns: true or false

GAP-categories of the chain or cochain complexes.

1.2-2 IsChainComplex
‣ IsChainComplex( C )( filter )

Returns: true or false

GAP-categories of the chain complexes.

1.2-3 IsCochainComplex
‣ IsCochainComplex( C )( filter )

Returns: true or false

GAP-categories of the cochain complexes.

1.2-4 CreateComplex
‣ CreateComplex( C, L )( operation )

Returns: a CAP object

The input is a complexes category \(\mathcal{C}^b(A)\) by chains or cochains and a list \(L\) with \(4\) entries: \(L[1]\) and \(L[2]\) are \(\mathbb{Z}\)-functions and \(L[3]\) and \(L[4]\) are integers or \(\pm\infty\). The output is an object \(C\in \mathcal{C}^b(A)\) whose object at \(i\in\mathbb{Z}\) is \(C^i:=L[1][i]\), differential at \(i\in\mathbb{Z}\) is \(\partial_{C}^i:=L[2][i]\). Its lower and upper bounds are \(L[3]\) resp. \(L[4]\).

1.2-5 CreateComplex
‣ CreateComplex( C, L )( operation )

Returns: a CAP object

The input is a complexes category \(\mathcal{C}^b(A)\) by chains or cochains, a dense-list \(L\) of morphisms in \(A\) and an integer \(\ell\). The output is an object \(C\in\mathcal{C}^b(A)\) whose differentials are \(\partial_{C}^{\ell}:=L[1], \partial_{C}^{\ell+1}:=L[2],\) etc.

1.2-6 Objects
‣ Objects( C )( attribute )

Returns: a \(\mathbb{Z}\)-function

Returns the objects of the complex as a \(\mathbb{Z}\)-function.

1.2-7 ObjectAt
‣ ObjectAt( C, i )( operation )

Returns: a CAP object

Returns the object \(C^i\) of the complex \(C\) at the index \(i\in\mathbb{Z}\).

1.2-8 \[\]
\[\]( C, i )( operation )

Returns: a CAP object

Delegates to ObjectAt(\(C\),\(i\)).

1.2-9 Differentials
‣ Differentials( C )( attribute )

Returns: a \(\mathbb{Z}\)-function

Returns the differentials of the complex as a \(\mathbb{Z}\)-function.

1.2-10 DifferentialAt
‣ DifferentialAt( C, i )( operation )

Returns: a CAP morphism

Returns the differential of the complex \(C\) at the index \(i\in\mathbb{Z}\).

1.2-11 \^
‣ \^( C, i )( operation )

Returns: a CAP object

Delegates to DifferentialAt(\(C\),\(i\)).

1.2-12 LowerBound
‣ LowerBound( C )( attribute )

Returns: integer or infinity

Returns the lower bound \(\ell\) of \(C\). I.e., the objects \(C^i\) are zero for all \(i\prec\ell\).

1.2-13 UpperBound
‣ UpperBound( C )( attribute )

Returns: integer or infinity

Returns the upper bound \(u\) of \(C\). I.e., the objects \(C^i\) are zero for all \(i\succ u\).

1.2-14 ObjectsSupport
‣ ObjectsSupport( C, m, n )( operation )

Returns: a list of integers

The input is a complex \(C\) and two integers \(m,n\). The output is the list of indices \(m\preceq i \preceq n\) where the objects of \(C\) are non-zero.

1.2-15 ObjectsSupport
‣ ObjectsSupport( C )( attribute )

Returns: a list of integers

The input is a complex \(C\) whose lower and upper bounds are integers. The output is the list of indices where the objects of \(C\) are non-zero.

1.2-16 DifferentialsSupport
‣ DifferentialsSupport( C, m, n )( operation )

Returns: a list of integers

The input is a complex \(C\) and two integers \(m,n\). The output is the list of indices \(m\preceq i \preceq n\) where the differentials of \(C\) are non-zero.

1.2-17 DifferentialsSupport
‣ DifferentialsSupport( C )( attribute )

Returns: a list of integers

The input is a complex \(C\) whose lower and upper bounds are integers. The output is the list of indices where the differentials of \(C\) are non-zero.

1.2-18 CocyclesAt
‣ CocyclesAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the kernel object of \(\partial_{C}^i\).

1.2-19 CocyclesEmbeddingAt
‣ CocyclesEmbeddingAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the kernel embedding of \(\partial_{C}^i\).

1.2-20 CoboundariesAt
‣ CoboundariesAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the image object of the differential \(\partial_{C}^{i-1}\).

1.2-21 CoboundariesEmbeddingAt
‣ CoboundariesEmbeddingAt( C, i )( operation )

Returns: a CAP morphism

The input is a cochain complex \(C\). The output is the image embedding of the differential \(\partial_{C}^{i-1}\).

1.2-22 CohomologyAt
‣ CohomologyAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the cohomology object of \(C\) at \(i\).

1.2-23 CohomologySupport
‣ CohomologySupport( C, m, n )( operation )

Returns: a list of integers

The input is a complex \(C\) and two integers \(m,n\). The output is the list of indices \(m\preceq i \preceq n\) where the cohomology objects of \(C\) are non-zero.

1.2-24 CohomologySupport
‣ CohomologySupport( C )( attribute )

Returns: a list of integers

The input is a complex \(C\) whose lower and upper bounds are integers. The output is the list of indices where the cohomology objects of \(C\) are non-zero.

1.2-25 CyclesAt
‣ CyclesAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the kernel object of \(\partial_{C}^i\).

1.2-26 CyclesEmbeddingAt
‣ CyclesEmbeddingAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the kernel embedding of \(\partial_{C}^i\).

1.2-27 BoundariesAt
‣ BoundariesAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the image object of the differential \(\partial_{C}^{i+1}\).

1.2-28 BoundariesEmbeddingAt
‣ BoundariesEmbeddingAt( C, i )( operation )

Returns: a CAP morphism

The input is a cochain complex \(C\). The output is the image embedding of the differential \(\partial_{C}^{i+1}\).

1.2-29 HomologyAt
‣ HomologyAt( C, i )( operation )

Returns: a CAP object

The input is a cochain complex \(C\). The output is the homology object of \(C\) at \(i\).

1.2-30 HomologySupport
‣ HomologySupport( C, m, n )( operation )

Returns: a list of integers

The input is a complex \(C\) and two integers \(m,n\). The output is the list of indices \(m\preceq i \preceq n\) where the homology objects of \(C\) are non-zero.

1.2-31 HomologySupport
‣ HomologySupport( C )( attribute )

Returns: a list of integers

The input is a complex \(C\) whose lower and upper bounds are integers. The output is the list of indices where the homology objects of \(C\) are non-zero.

1.2-32 IsExact
‣ IsExact( C )( property )

Returns: a list of integers

The input is a complex \(C\) whose lower and upper bounds are integers. The output is wheather the (co)homology support is empty.

1.2-33 IsExact
‣ IsExact( C, m, n )( operation )

Returns: a list of integers

The input is a complex \(C\) and two integers \(m,n\). The output is wheather the (co)homology support between \(m\) and \(n\) is empty.

1.2-34 AsChainComplex
‣ AsChainComplex( C )( attribute )

Returns: a CAP object

Convert a cochain complex into a chain complex.

1.2-35 AsCochainComplex
‣ AsCochainComplex( C )( attribute )

Returns: a CAP object

Convert a chain complex into a cochain complex.

1.3 Constructing morphisms

1.3-1 IsChainOrCochainMorphism
‣ IsChainOrCochainMorphism( phi )( filter )

Returns: true or false

GAP-categories of the complex morphisms.

1.3-2 IsChainMorphism
‣ IsChainMorphism( phi )( filter )

Returns: true or false

GAP-categories of the chain complex morphisms.

1.3-3 IsCochainMorphism
‣ IsCochainMorphism( phi )( filter )

Returns: true or false

GAP-categories of the cochain complex morphisms.

1.3-4 CreateComplexMorphism
‣ CreateComplexMorphism( C, S, L, R )( operation )

Returns: a CAP morphism

The input is a complexes category \(\mathcal{C}^b(A)\) by chains or cochains, two objects \(S\) and \(R\) and a list \(L\) with \(3\) entries: \(L[1]\) is a \(\mathbb{Z}\)-function; \(L[2]\) and \(L[3]\) are integers or \(\pm\infty\). The output is the morphism \(\phi:S \to R\) in \(\mathcal{C}^b(A)\) whose morphism at \(i\in\mathbb{Z}\) is \(L[1][i]\) and its lower and upper bounds are \(L[2]\) resp. \(L[3]\).

1.3-5 CreateComplexMorphism
‣ CreateComplexMorphism( C, S, L, ell, R )( operation )

Returns: a CAP morphism

The input is a complexes category \(\mathcal{C}^b(A)\) by chains or cochains, two objects \(S\) and \(R\) and a dense-list \(L\) of morphisms in \(A\) and an integer \(\ell\). The output is the morphism \(\phi:S \to R\) in \(\mathcal{C}^b(A)\) whose morphism at \(\ell\) is \(L[1]\), at \(\ell+1\) is \(L[2]\), etc. In particular, \(\ell\) is a lower bound of \(\phi\).

1.3-6 Morphisms
‣ Morphisms( phi )( attribute )

Returns: a \(\mathbb{Z}\)-function

Returns the morphisms as a \(\mathbb{Z}\)-function.

1.3-7 MorphismAt
‣ MorphismAt( phi, i )( operation )

Returns: a CAP morphism

Returns the morphism of \(\phi\) at the index \(i\in\mathbb{Z}\).

1.3-8 \[\]
\[\]( phi, i )( operation )

Returns: a CAP morphism

Delegates to MorphismAt(\(\phi\), \(i\)).

1.3-9 LowerBound
‣ LowerBound( phi )( attribute )

Returns: integer or infinity

Returns an integer \(\ell\) with \(S^i=R^i=0\) for all \(i\prec\ell\).

1.3-10 UpperBound
‣ UpperBound( phi )( attribute )

Returns: integer or infinity

Returns an integer \(u\) with \(S^i=R^i=0\) for all \(i\succ u\).

1.3-11 MorphismsSupport
‣ MorphismsSupport( phi, m, n )( operation )

Returns: a list of integers

The input is a complex morphism \(\phi\) and two integers \(m,n\). The output is the list of indices \(m\preceq i \preceq n\) where the morphisms of \(\phi\) are non-zero.

1.3-12 MorphismsSupport
‣ MorphismsSupport( phi, i )( attribute )

Returns: a list of integers

The input is a complex morphism \(\phi\) whose lower and upper bounds are integers. The output is the list of indices where the morphisms of \(\phi\) are non-zero.

1.3-13 CyclesFunctorialAt
‣ CyclesFunctorialAt( phi, i )( operation )

Returns: a CAP morphism

The input is a complex morphism \(\phi:S \to R\) and an integer \(i\). The output is the morphism induced by the functoriality of the cycle objects of \(S\) and \(R\) at the index \(i\).

1.3-14 CocyclesFunctorialAt
‣ CocyclesFunctorialAt( phi, i )( operation )

Returns: a CAP morphism

The input is a complex morphism \(\phi:S \to R\) and an integer \(i\). The output is the morphism induced by the functoriality of the cocycle objects of \(S\) and \(R\) at the index \(i\).

1.3-15 CohomologyFunctorialAt
‣ CohomologyFunctorialAt( phi, i )( operation )

Returns: a CAP morphism

The input is a complex morphism \(\phi:S \to R\) and an integer \(i\). The output is the morphism induced by the functoriality of the cohomology objects of \(S\) and \(R\) at the index \(i\).

1.3-16 HomologyFunctorialAt
‣ HomologyFunctorialAt( phi, i )( operation )

Returns: a CAP morphism

The input is a complex morphism \(\phi:S \to R\) and an integer \(i\). The output is the morphism induced by the functoriality of the homology objects of \(S\) and \(R\) at the index \(i\).

1.3-17 IsQuasiIsomorphism
‣ IsQuasiIsomorphism( phi )( property )

Returns: true or false

Returns wheather \(\phi\) is a quasi-isomorphism, i.e., wheather it induces isomorphisms between the (co)homology objects of \(S\) and \(R\).

1.3-18 IsHomotopicToZeroMorphism
‣ IsHomotopicToZeroMorphism( phi )( property )

Returns: true or false

Returns wheather \(\phi\) is homotopic to the zero morphism.

1.3-19 WitnessForBeingHomotopicToZeroMorphism
‣ WitnessForBeingHomotopicToZeroMorphism( phi )( attribute )

Returns: \(\mathbb{Z}\)-function

Returns a \(\mathbb{Z}\)-function \(w\) witnessing that \(\phi\) is homotopic to the zero morphism. If \(\phi\) is a chain morphism, then \(w^i\) is a morphism from \(S^i\) to \(R^{i+1}\) and if \(\phi\) is a cochain morphism, then \(w^i\) is a morphism from \(S^i\) to \(R^{i-1}\).

1.3-20 AsChainComplexMorphism
‣ AsChainComplexMorphism( phi )( attribute )

Returns: a CAP morphism

Convert a chain morphism into a cochain morphism.

1.3-21 AsCochainComplexMorphism
‣ AsCochainComplexMorphism( phi )( attribute )

Returns: a CAP morphism

Convert a cochain morphism into a chain morphism.

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