fact: Definition beta_subst : forall M (Mapp: isApp M) (MLabs: isAbs (appBodyL Mapp)), correct_subst (absBody MLabs) {x/(lift (appBodyR Mapp) 1)}.
imports: CoLoR(RelExtras ListExtras TermsRed TermsConv LogicUtil) Coq(Setoid PeanoNat Lia)