English
There is an SMul instance on LinearMap, giving a scalar action by S on σ₁₂-linear maps M →ₛₗ[σ₁₂] M₂.
Русский
Существует инстанс SMul на линейных отображениях, задающий скалярное действие S на σ₁₂-линейных отображениях.
LaTeX
$$$\text{SMul } S (M \to_{\sigma_{12}} M_2)$$$
Lean4
instance [SMulCommClass S T M₂] : SMulCommClass S T (M →ₛₗ[σ₁₂] M₂) :=
⟨fun _ _ _ ↦ ext fun _ ↦ smul_comm _ _ _⟩
-- example application of this instance: if S -> T -> R are homomorphisms of commutative rings and
-- M and M₂ are R-modules then the S-module and T-module structures on Hom_R(M,M₂) are compatible.