proposition: Lemma diffX_neq0 (i j : 'I_n) : i != j -> 'X_i - 'X_j != 0.
proof: Proof. Proof using. by apply contra; rewrite subr_eq0 => /eqP /polyX_inj ->. Qed.
imports: HB(structures) mathcomp(all_ssreflect) mathcomp(ssralg ssrint fingroup perm zmodp binomial) mathcomp(ssrcomplements freeg mpoly) tools permcomp presentSn sorted partition