proposition: Lemma ker_reprGLm : 'ker reprGLm = rker rG.
proof: Proof. apply/setP=> x; rewrite !inE mul1mx; apply: andb_id2l => Gx. by rewrite -val_eqE val_reprGLm. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop prime) mathcomp(ssralg poly finset fingroup morphism perm) mathcomp(automorphism quotient gproduct action finalg) mathcomp(zmodp commutator cyclic center pgroup gseries) mathcomp(nilpotent sylow maximal abelian matrix) mathcomp(mxalgebra mxrepresentation)