proposition: Lemma sign_irr : mx_irreducible sign_repr.
proof: Proof. apply: mx_abs_irrW; exact: linear_mx_abs_irr. Qed.
imports: mathcomp(all_ssreflect) mathcomp(fingroup perm ssralg morphism perm action) mathcomp(zmodp) mathcomp(vector matrix mxalgebra ssrnum algC) mathcomp(mxrepresentation classfun character) permcomp tools partition congr cycles cycletype presentSn