False ↔ Erdos189.Erdos189For (fun a b c d => (affineSpan ℝ {a, b}).direction ⟂ (affineSpan ℝ {b, c}).direction ∧ (affineSpan ℝ {b, c}).direction ⟂ (affineSpan ℝ {c, d}).direction ∧ (affineSpan ℝ {c, d}).direction ⟂ (affineSpan ℝ {d, a}).direction) fun a b c d => dist a b * dist b c