proposition: Lemma mxdiag0 : \mxdiag_i (0 : 'M[V]_(p_ i)) = 0.
proof: Proof. by under [LHS]eq_mxdiag do rewrite -[0]subr0; rewrite mxdiagB subrr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype finfun bigop finset fingroup perm order) mathcomp(div prime binomial ssralg countalg finalg zmodp)