proposition: Lemma nf_revCE u v: T1bad <> T1omega * u + \F v.
proof: Proof. case: (altP (u =P zero)); first by move => ->; case v. move/mul_omega_limit;set w:= (T1omega * u). case: v; first by rewrite T1addn0 => sa sb; move: sa; rewrite - sb. by move => v; case w => // a n b; case a. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(fintype bigop)