DEFINITION subst1_confluence_lift() TYPE = ∀t0:T .∀t1:T .∀u:T .∀i:nat .(subst1 i u t0 (lift (S O) i t1))→∀t2:T.(subst1 i u t0 (lift (S O) i t2))→(eq T t1 t2) BODY =Show proof