proposition: Lemma FL_trans s t u : t \in FL s -> s \in FL u -> t \in FL u.
proof: Proof. move => A B. move: A. apply/subP. exact: FL_trans_mut.1. Qed.
imports: Relations Lia Setoid Morphisms mathcomp(all_ssreflect) CompDecModal.libs(edone bcase fset base modular_hilbert sltype rewrite_inequality fset_tac)