Universal homeomorphism

In algebraic geometry, a universal homeomorphism is a morphism of schemes formula_1 such that, for each morphism formula_2, the base change formula_3 is a homeomorphism of topological spaces.
A morphism of schemes is a universal homeomorphism if and only if it is integral, radicial and surjective. In particular, a morphism of locally of finite type is a universal homeomorphism if and only if it is finite, radicial and surjective.
For example, an absolute Frobenius morphism is a universal homeomorphism.