lean_workbook_plus_77640

Proved

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

Prove that if $f: A \rightarrow A$ is a surjective map on a finite set $A$ , then $f$ is injective.

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_77640 (A : Type*) [Finite A] (f : A → A) (hf: Function.Surjective f) : Function.Injective f   :=  by sorry

Source