Inverse image functor
FUNCTOR BETWEEN CATEGORIES OF ABELIAN-GROUP-VALUED SHEAVES INDUCED BY A CONTINUOUS MAP BETWEEN TOPOLOGICAL SPACES; SHEAFIFICATION OF THE PRESHEAF ASSOCIATING TO AN OPEN SET U THE INDUCTIVE LIMIT OF THE GROUPS ASSOCIATED TO OPEN SUPERSETS OF U’S IMAGE
Inverse image sheaf
In mathematics, specifically in algebraic topology and algebraic geometry, an inverse image functor is a contravariant construction of sheaves; here “contravariant” in the sense given a map f : X \to Y, the inverse image functor is a functor from the category of sheaves on Y to the category of sheaves on X. The direct image functor is the primary operation on sheaves, with the simplest definition.