English
The Tendsto of the swap4 rearrangement holds for the product of filters.
Русский
Сохранение предельности под перестановкой swap4 в произведении фильтров.
LaTeX
$$$\mathrm{Tendsto}\ (\lambda p : (\alpha \times \beta) \times \gamma \times \delta \Rightarrow ((p.1.1, p.2.1), (p.1.2, p.2.2)))\ ((f \times\! g) \times\! (h \times\! k))\ ((f \times\! h) \times\! (g \times\! k))$$$
Lean4
theorem tendsto_swap4_prod {h : Filter γ} {k : Filter δ} :
Tendsto (fun p : (α × β) × γ × δ => ((p.1.1, p.2.1), (p.1.2, p.2.2))) ((f ×ˢ g) ×ˢ (h ×ˢ k))
((f ×ˢ h) ×ˢ (g ×ˢ k)) :=
map_swap4_prod.le