Néron–Ogg–Shafarevich criterion
In mathematics, the Néron–Ogg–Shafarevich criterion states that if A is an elliptic curve or abelian variety over a local field K and ℓ is a prime not dividing the characteristic of the residue field of K then A has good reduction if and only if the ℓ-adic Tate module Tℓ of A is unramified. introduced the criterion for elliptic curves. used the results of to extend it to abelian varieties,
and named the criterion after Ogg, Néron and Igor Shafarevich.
