Module fc_subst (wf : fc_wf_sig) (weak : fc_weak_sig) <: fc_subst_sig.
Export wf.
Export weak.
Set Bullet Behavior "Strict Subproofs".
Set Implicit Arguments.
(* --------------------------------------- *)

Lemma AnnCtx_strengthen : forall G1 G2, AnnCtx (G2 ++ G1) -> AnnCtx G1.