A Dedekind's Criterion over Valued Fields

Abstract

Let $(K,\nu)$ be an arbitrary-rank valued field, $R_\nu$ its valuation ring, $K(\alpha)/K$ a separable finite field extension generated over $K$ by a root of a monic irreducible polynomial $f\in R_\nu[X]$. We give necessary and sufficient conditions for $R_\nu[\alpha]$ to be integrally closed. We further characterize the integral closedness of $R_\nu[\alpha]$ based on information about the valuations on $K(\alpha)$ extending $\nu$. Our results enhance and generalize some existing results in the relevant literature. Some applications and examples are also given.