lean_workbook_plus_71610

Proved

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

Find all functions $f\colon \mathbb{Z} \to \mathbb{Z}$ such that \n\n

f(y) - f(y + f(x)) = x

for all $x,y \in\mathbb{Z}$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_71610 (f : ℤ → ℤ) (hf : ∀ x y, f y - f (y + f x) = x) : ∃ a, ∀ x, f x = a - x   :=  by sorry

Source