English
Given isotypic decomposition, there exists a relation between S and S' via linear isomorphisms preserving isotypicity.
Русский
Существуют коэффициенты и изоморфизмы, устанавливающие эквивалентность изотипических компонент.
LaTeX
$$$$ \\text{IsIsotypicOfType}(R,M,S) \\iff \\text{relation via isotypic component.} $$$$
Lean4
/-- If an `R`-module `M` is the direct sum of fully invariant submodules `Nᵢ`,
then `End R M` is isomorphic to `Πᵢ End R Nᵢ` as an algebra. -/
noncomputable def algEquiv [Module R₀ M] [IsScalarTower R₀ R M] : Module.End R M ≃ₐ[R₀] Π i, Module.End R (N i)
where
__ := ind.ringEquiv iSup_top invar
commutes' _ := rfl