intros a b c h_le
n : ℕ
⊢ ∀ (a b c : Variables n order.GrLex), Order.grlex a b → Order.grlex (Variables.mul a c) (Variables.mul b c)
n : ℕ
a b c : Variables n order.GrLex
h_le : Order.grlex a b
⊢ Order.grlex (Variables.mul a c) (Variables.mul b c)