A bicontinuous active morphism is called an effective morphism . U , then we say that U is effective . Y is a morphism. A surjective effective morphism is an isomorphism. Y is an effective morphism.
V is an isomorphism of subobjects.
Then gf is quasi-effective. The composite of two injective active morphisms is an injective active morphism. A ctive morphisms are stable under base extensions. X e C is effective. Suppose C is an everywhere effective presite.