English
There exists SMulCommClass M Nᵐᵒᵖ N under the given assumptions, with smul_comm m n z := mul_smul_comm m n z.
Русский
Существуют SMulCommClass M N^{op} N при данных предпосылках, с отношением smul_comm m n z := mul_smul_comm m n z.
LaTeX
$$$SMulCommClass M N^{op} N$ with smul_comm x y z := by applying mul_smul_comm.$$
Lean4
@[to_additive]
instance opposite_mid {M N} [Mul N] [SMul M N] [IsScalarTower M N N] : SMulCommClass M Nᵐᵒᵖ N where
smul_comm x y
z := by
induction y using MulOpposite.rec'
simp only [smul_mul_assoc, MulOpposite.smul_eq_mul_unop]
-- The above instance does not create an unwanted diamond, the two paths to
-- `MulAction αᵐᵒᵖ αᵐᵒᵖ` are defeq.