Hom Functor - Properties

Properties

Note that a functor of the form

Hom(–, C) : Cop → Set

is a presheaf; likewise, Hom(C, –) is a copresheaf.

A functor F : CSet that is naturally isomorphic to Hom(C, –) is called a representable functor or sometimes a representable copresheaf; likewise, a contravariant functor equivalent to Hom(–, C) might be called corepresentable.

Note that Hom(–, –) : Cop × CSet is a profunctor, and, specifically, it is the identity profunctor

,

The internal hom functor preserves limits; that is, sends limits to limits, while sends limits to colimits. In a certain sense, this can be taken as the definition of a limit or colimit.

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