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Operations on Mappings

Operations on Mappings

Subsections

Composition

Although compatible maps can be composed by repeated application, say g(f(x)), it is also possible to create a composite map.

f * g : Map, Map -> Map
Given a mapping f : A -> B, and a mapping g : B -> C, construct the composition h of the mappings f and g as the mapping h=g o f : A -> C.

(Co)Domain and (Co)Kernel

The domain and codomain of any map can simply be accessed. Only certain intrinsic maps also support the formation of image, kernel and cokernel.

Domain(f) : Map -> Struct
The domain of the mapping f.
Codomain(f) : Map -> Struct
The codomain of the mapping f.
Image(f) : Map -> Elt
Given a mapping f with domain A and codomain B, return the image of A in B as a substructure of B. This function is currently available only for certain intrinsic maps.
Kernel(f) : Map -> Struct
Given the homomorphism f with domain A and codomain B, return the kernel of f as a substructure of A. This function is currently available only for certain intrinsic maps.

Function

For a map given by a rule, it is possible to get access to the rule as a user defined function.

Function(f) : Map -> UserProgram
The function underlying the mapping f. Only available if f has been defined by the user by means of a rule map (ie an expression for the image under f of an arbitrary element of the domain).
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