(grammar) A function word. / (object-oriented programming) A function object.

plural of functor

(category theory) A functor from some category to the category of sets (Set) which is naturally isomorphic to a hom functor.

(category theory) A functor which maps a morphism f:X → Y to a morphism F(f):F(Y) → F(X), such that if h=g∘f, then F(h)=F(f)∘F(g).

plural of representable functor

(category theory) a functor that forgets or drops some or all of its input's structure or properties before mapping to the output

(category theory) A category whose objects are functors (from some fixed given domain category to some fixed given codomain category) and whose morphisms are natural transformations.

(category theory) A functor from a category to itself which maps each object of that category to itself and each morphism of that category to itself.

(category theory) One of a pair of functors such that the domain and codomain of one of them are identical to the codomain and domain of the other one, respectively, and such that there is a pair of natural transformations which turns the pair of functors into an adjunction.

plural of adjoint functor