Category.md (443B)
1 # Category 2 3 **Definition:** A category consists of a collection of objects and a collection of morphisms. 4 5 so that: 6 7 - Each morphism has a domain and codomain among the collection of objects 8 - Each object has an identity morphism 9 - For any composable morphisms f,g there is a composite morphism whose domain is equal to the domain of f and whose codomain is equal to the codomain of g. Additionally if f: X -> Y and g: Y -> Z then gf: X -> Z.