English
The product map is symmetric up to the natural commutativity isomorphism of the tensor product: mulMap B A equals mulMap A B composed with the commutativity map.
Русский
Произведение мап симметрично относительно естественного изоморфизма коммутативности тензорного произведения: mulMap B A = mulMap A B ∘ TensorProduct.comm.
LaTeX
$$$\text{mulMap } B A = (\text{mulMap } A B) \circ (\text{Algebra.TensorProduct.comm } R B A)$$$
Lean4
theorem mulMap_comm : mulMap B A = (mulMap A B).comp (Algebra.TensorProduct.comm R B A) := by ext <;> simp