English
If each R_i carries a multiplication and the subobjects B_i are closed under multiplication with compatible topology, then the restricted product has continuous multiplication.
Русский
Если в каждом R_i задано умножение, а подобъекты B_i замкнуты по умножению и соблюдают топологию, то ограниченное произведение имеет непрерывное умножение.
LaTeX
$$$\\mathrm{ContinuousMul}\\left(\\mathrm{RestrictedProduct}(\\{R_i\\}, \\{B_i\\}; \\mathrm{cofinite})\\right)$$$
Lean4
@[to_additive]
instance continuousSMul {G : Type*} [TopologicalSpace G] [Π i, SMul G (R i)] [∀ i, SMulMemClass (S i) G (R i)]
[∀ i, ContinuousSMul G (R i)] : ContinuousSMul G (Πʳ i, [R i, B i]) where
continuous_smul := by
rw [continuous_dom_prod_left hBopen.out]
exact fun S hS ↦ (continuous_inclusion hS).comp continuous_smul