proposition: Fact ltz_def m n : (ltz m n) = (n != m) && (lez m n).
proof: Proof. by move: m n => [] m [] n //=; rewrite (ltn_neqAle, leq_eqVlt) // eq_sym. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)