proposition: Lemma weak_ent_inv A : weak_ent A -> weak_ent (A^-1)%classic.
proof: Proof. move=> [B ? sBA]; exists (B^-1)%classic; first exact: entourage_inv. by move=> ??; exact/sBA. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed