intros; simpl in |- *.
red in |- *; simpl in |- *.
intros; (apply Sym; auto with algebra).
Qed.

Lemma row_comp :
forall (F : field) (m n : Nat) (M M' : matrix F m n) (i i' : fin m),
M =' M' in _ -> i =' i' in _ -> row M i =' row M' i' in _.