proposition: Lemma mxsemisimple0 : mxsemisimple 0.
proof: Proof. exists 'I_0 (fun _ => 0); [by case | by rewrite big_ord0 | ]. by rewrite mxdirectE /= !big_ord0 mxrank0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop prime) mathcomp(ssralg poly polydiv finset fingroup morphism) mathcomp(perm automorphism quotient finalg action zmodp) mathcomp(commutator cyclic center pgroup matrix mxalgebra) mathcomp(mxpoly)