proposition: Lemma mx_rsim_def n1 n2 (rG1 : reprG n1) (rG2 : reprG n2) : mx_rsim rG1 rG2 -> exists B, exists2 B', B' *m B = 1%:M & forall x, x \in G -> rG1 x = B *m rG2 x *m B'.
proof: Proof. case=> B def_n1; rewrite def_n1 in rG1 B *; rewrite row_free_unit => injB homB. by exists B, (invmx B) => [|x Gx]; rewrite ?mulVmx // -homB // mulmxK. 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)