In category theory an epimorphism (also called an epic morphism or an epi)'s a morphism f : X → Y which's right-cancellative in the sense that, for all morphisms,: g_1 circ f = g_2 circ f Rightarrow g_1 = g_2. Epimorphisms are analogues of surjective functions, but they aren't exactly the same. The dual of an epimorphism's a monomorphism (for example an epimorphism in a category C's a monomorphism in the dual category Cop). Many authors in abstract algebra and universal algebra define an… (More on Epimorphism)