Valuative criterion for properness
= Valuative criterion for properness
For a finite-type morphism of <Noetherian scheme>[Noetherian schemes], properness is equivalent to existence and uniqueness in every lifting problem from the generic point $\operatorname{Spec}K$ of a <valuation ring> $R$ to $\operatorname{Spec}R$.
This is the existence-and-uniqueness part of the <valuative criterion>.