lean_workbook_plus_77333

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

Prove that $\frac{|x|}{(1+x^2)(1+y^2)} \leq \frac{1}{2}$ for all $x, y \in \mathbb{R}$ .

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_77333 : ∀ x y : ℝ, |x| / ((1 + x ^ 2) * (1 + y ^ 2)) ≤ 1 / 2   :=  by sorry

Source