proposition: Lemma max_pos (x y : posNat) : maxn (val x) (val y) > 0.
proof: Proof. by case: x y=>x pfx [y pfy]; rewrite leq_max pfx pfy. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq bigop fintype finset) pcm(options axioms prelude seqperm pred seqext)