Associated inertia (reviewed)

Let $L/K$ be a finite extension, let $L^{un}/K$ be the maximal unramified subextension of $L/K$, and let $\varphi \in L^{un}[x]$ be an Eisenstein polynomial defining $L/L^{un}$. The associated inertia of a segment of the ramification polygon of $\varphi$ is the least common multiple of the degrees of the irreducible factors of the residual polynomial of that segment. The associated inertias are divisors of the inertia degree of $\varphi$ and are invariants of $L/K$.