lean_workbook_plus_29991

Proved

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

If $A\cup B=A\cup C$ & $A\cap B=A\cap C$ prove that $B=C$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_29991 {α : Type} (A B C : Set α) (h1 : A ∪ B = A ∪ C) (h2 : A ∩ B = A ∩ C) : B = C   :=  by sorry

Source