Maps may either be "functions" or "morphisms", though the terms share some overlap. The term "map" may be used to distinguish some special types of functions, such as homomorphisms. For example, a linear map is a homomorphism of vector spaces, while the term linear function may have this meaning as well as another one. In category theory, a map may refer to a morphism, which is a generalization of the idea of a function. In some occasions, the term "transformation" can also be used interchangeably. There are also a few less common uses in logic and graph theory.