Quasi-compact morphism

In algebraic geometry and related fields, a **quasi-compact morphism** is a type of morphism of schemes or topological spaces that relates to the compactness of the images of certain sets. A morphism of schemes \( f: X \to Y \) is called **quasi-compact** if the preimage of every quasi-compact subset of \( Y \) under \( f \) is quasi-compact in \( X \).