lean_workbook_plus_76213

Proved

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

If $f(1/2)=f(1/4)$ or $f(1/2)=f(3/4)$ then f is not injective.

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_76213 (f : ℝ → ℝ) (hf: f (1 / 2) = f (1 / 4) ∨ f (1 / 2) = f (3 / 4)) : ¬ Function.Injective f   :=  by sorry

Source