Canonical mulmx_additive m n p A := Additive (@mulmxBr m n p A).Implicit Type A : 'M[R]_(m, n).Local Notation mulmxr := (mulmxr_head tt).Definition lin_mulmxr B := lin_mx (mulmxr B).

Lemma mulmxr_is_linear B : linear (mulmxr B).