lean_workbook_plus_15362

Proved

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

Let $P(x,y)$ be the assertion $f(f(x+y)-x)f(f(x+y)-y)=xy$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_15362 (f : ℤ → ℤ) (hf: f = fun x ↦ x) : ∀ x y, f (f (x + y) - x) * f (f (x + y) - y) = x * y   :=  by sorry

Source