fact: Definition proper_ideal (R : ringType) (S : {pred R}) : Prop := 1 \notin S /\ forall a, {in S, forall u, a * u \in S}.
imports: HB(structures) mathcomp(ssreflect eqtype choice ssreflect ssrbool ssrnat) mathcomp(ssrfun seq ssralg generic_quotient)