自同态

Also known as End

In abstract algebra, an endomorphism is a homomorphism from a mathematical object to itself. More generally in category theory, an endomorphism is a morphism from an object in some category to itself. An endomorphism that is also an isomorphism is an automorphism. For example, an endomorphism of a vector space V is a linear map f: V → V, and an endomorphism of a group G is a group homomorphism f: G → G. frame|right|Orthogonal projection onto a line, , is a [[linear operator on the plane. This is an example of an endomorphism that is not an automorphism.]]