proposition: Lemma sltNge ks t1 t2 : t1 <[ks] t2 = ~~ t2 <=[ks] t1.
proof: Proof. by rewrite /seq_lt /seq_le ltnNge. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path interval order) pcm(options prelude ordtype seqext)