lean_workbook_plus_29421

Proved

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

Let $a,b,c,d\in[ 0: 1]$ . Prove that: $a(1-d)+b(1-a)+c(1-b)+d(1-c)\leq2$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_29421 (a b c d : ℝ) (ha : a ∈ Set.Icc 0 1) (hb : b ∈ Set.Icc 0 1) (hc : c ∈ Set.Icc 0 1) (hd : d ∈ Set.Icc 0 1) : a * (1 - d) + b * (1 - a) + c * (1 - b) + d * (1 - c) ≤ 2   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook

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