proposition: Lemma funS_subst_funS M G (MG: correct_subst M G) : isFunS M -> isFunS (subst MG).
proof: Proof. intro. term_inv M. apply funS_is_funS with f. change (^f) with (term Tr). apply funS_presubst; trivial. Qed.
imports: CoLoR(RelExtras ListPermutation TermsConv ListUtil ListExtras LogicUtil) Coq(Arith Lia)