English
Join of two semisimple submodules is semisimple.
Русский
Сумма двух полупрямых подмодулей полупрямой.
LaTeX
$$IsSemisimpleModule R ↥(p ⊔ q)$$
Lean4
theorem sup {p q : Submodule R M} (_ : IsSemisimpleModule R p) (_ : IsSemisimpleModule R q) :
IsSemisimpleModule R ↥(p ⊔ q) := by
let f : Bool → Submodule R M := Bool.rec q p
rw [show p ⊔ q = ⨆ i ∈ Set.univ, f i by rw [iSup_univ, iSup_bool_eq]]
exact isSemisimpleModule_biSup_of_isSemisimpleModule_submodule (by rintro (_ | _) _ <;> assumption)