Section GringMx.
Variables (n : nat) (rG : mx_representation F G n).
Hypothesis F'G : [char F]^'.-group G.
End GringMx.
Definition gset_mx (A : {set gT}) := \sum_(x in A) aG x.
Local Notation tG := #|pred_of_set (classes (gval G))|.
Definition classg_base := \matrix_(k < tG) mxvec (gset_mx (enum_val k)).
Let groupCl : {in G, forall x, {subset x ^: G <= G}}.
Definition irrType := socleType aG.
Identity Coercion type_of_irrType : irrType >-> socleType.
Variable sG : irrType.
Definition irr_degree (i : sG) := \rank (socle_base i).
Local Notation "'n_ i" := (irr_degree i) : group_ring_scope.
Local Open Scope group_ring_scope.

Lemma principal_comp_subproof : mxsimple aG (rfix_mx aG G).