proposition: Lemma bigAdrop s xs : mprv (\and_(<- s :: xs) ---> \and_(<- xs)).
proof: Proof. apply: and_sub => x. by rewrite !inE => ->. Qed.
imports: mathcomp(all_ssreflect) CompDecModal.libs(edone base fset induced_sym) Setoid Morphisms Relation_Definitions