English
Continuity of the algebra map is equivalent to continuity of the map (r,a) ↦ r • a when [ContinuousMul A] holds.
Русский
Непрерывность алгебраического отображения эквивалентна непрерывности отображения (r,a) ↦ r • a при условии [ContinuousMul A].
LaTeX
$$$\text{Continuous algebra map} \iff \text{Continuous}(\lambda p : R \times A, p_1 \cdot p_2)$$$
Lean4
theorem continuous_algebraMap_iff_smul [ContinuousMul A] :
Continuous (algebraMap R A) ↔ Continuous fun p : R × A => p.1 • p.2 :=
by
refine
⟨fun h => ?_, fun h =>
have : ContinuousSMul R A := ⟨h⟩;
continuous_algebraMap _ _⟩
simp only [Algebra.smul_def]
exact (h.comp continuous_fst).mul continuous_snd