English
Tendsto f l1 l2 is equivalent to RTendsto' (graph f) l1 l2.
Русский
Предел функции равен предельному поведению относительно графика: Tendsto f l1 l2 ⇔ RTendsto' (graph f) l1 l2.
LaTeX
$$$ \\mathrm{Tendsto}\\, f\\, l_1\\, l_2 \\iff \\mathrm{RTendsto}'\\, (\\mathrm{Function.graph}\\, f)\\, l_1\\, l_2 $$$
Lean4
theorem tendsto_iff_rtendsto' (l₁ : Filter α) (l₂ : Filter β) (f : α → β) :
Tendsto f l₁ l₂ ↔ RTendsto' (Function.graph f) l₁ l₂ := by
simp [tendsto_def, Function.graph, rtendsto'_def, SetRel.preimage, Set.preimage]