proposition: Lemma trmx0 : forall (m n : nat), (@null_mx m n)^T === @null_mx n m.
proof: Proof. by move=> m n; rewrite/trmx/null_mx/addmx/oppmx/scalemx; reflexivity. Qed.
imports: ssreflect ssrbool ssrfun eqtype ssrnat seq choice fintype finfun bigops ssralg groups perm zmodp morphisms Ring RingClass bigopsClass Setoid Morphisms