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1 Filters and constructors
 1.1 Filters
 1.2 Constructors
 1.3 Attributes and properties

1 Filters and constructors

1.1 Filters

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

Returns: a boolian

The Gap filter of the Cap quotient categories.

1.1-2 IsQuotientCategoryMorphism
‣ IsQuotientCategoryMorphism( alpha )( filter )

Returns: a boolian

The gap category of quotient categories morphisms

1.1-3 IsQuotientCategoryCell
‣ IsQuotientCategoryCell( a, object )( filter )

Returns: true or false

The GAP category of cells in the quotient category.

1.1-4 IsQuotientCategoryObject
‣ IsQuotientCategoryObject( a, object )( filter )

Returns: true or false

The GAP category of objects in the quotient category.

1.2 Constructors

1.2-1 QuotientCategory
‣ QuotientCategory( C, F )( operation )

Returns: a Cap category

The input is a category \(C\) and a function \(F\). For two objects \(a\) and \(b\) in \(C\), the function \(F\) can be applied on two morphisms \(\alpha,\beta \in \mathrm{Hom}_C(a,b)\) and returns true if \(\alpha \sim \beta\) and false otherwise. The output is the quotient category \(C/F\).

1.2-2 QuotientCategoryMorphism
‣ QuotientCategoryMorphism( _a_, alpha, _b_ )( operation )

Returns: a morphism

The arguments are two objects \(\underline{a}, \underline{b}\) in a quotient category \(Q=C/F\) and a morphism \(\alpha:a \rightarrow b\) in \(C\). The output is \(\underline{\alpha}: \underline{a} \rightarrow \underline{b}\) in \(Q\).

1.2-3 QuotientCategoryMorphism
‣ QuotientCategoryMorphism( Q, alpha )( operation )

Returns: a morphism

The input is a quotient category \(Q=C/F\) and a morphism \(\alpha:a \rightarrow b\) in \(C\). The output is \(\underline{\alpha}: \underline{a} \rightarrow \underline{b}\) in \(Q\).

1.2-4 \/
‣ \/( Q, alpha )( operation )

Returns: a morphism

The input is a quotient category \(Q=C/F\) and a morphism \(\alpha:a \rightarrow b\) in \(C\). The output is \(\underline{\alpha}: \underline{a} \rightarrow \underline{b}\) in \(Q\).

1.2-5 QuotientCategoryObject
‣ QuotientCategoryObject( Q, a )( operation )

Returns: an object

The input is a quotient category \(Q=C/F\) and an object \(a \in C\). The output is \(\underline{a} \in Q\).

1.2-6 \/
‣ \/( a, Q )( operation )

Returns: an object

The input is a quotient category \(Q=C/F\) and an object \(a \in C\). The output is \(\underline{a} \in Q\).

1.3 Attributes and properties

1.3-1 UnderlyingCategory
‣ UnderlyingCategory( Q )( attribute )

Returns: a category

The input is a quotient category \(Q := C/F\). The output is the category \(C\).

1.3-2 CongruencyTestFunctionForQuotientCategory
‣ CongruencyTestFunctionForQuotientCategory( Q )( attribute )

Returns: a function

The input is a quotient category \(Q := C/F\). The output is the congruence test function \(F\).

1.3-3 ProjectionFunctor
‣ ProjectionFunctor( Q )( attribute )

Returns: a functor

The input is a quotient category \(Q := C/F\). The output is the canonical projection functor \(\pi:C \rightarrow C/F\).

1.3-4 UnderlyingCell
‣ UnderlyingCell( _alpha_ )( attribute )

Returns: a morphism

The input is a morphism \(\underline{\alpha}: \underline{a} \rightarrow \underline{b}\) in some quotient category \(Q=C/F\) and the output is \(\alpha: a \rightarrow b\) in \(C\).

1.3-5 UnderlyingCell
‣ UnderlyingCell( _a_ )( attribute )

Returns: an object

The input is an object \(\underline{a}\) in some quotient category \(Q=C/F\) and the output is \(a\) in \(C\).

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