proposition: Lemma invalidX m i ts (g : rform i ts m true) : valid (unpack (pivot g)) = false.
proof: Proof. by rewrite undefX valid_undef. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq) pcm(options pred prelude) pcm(pcm unionmap natmap)