A fourth-power bound on cyclic cubic products
ProvedWorkbookSource.base_9764lean-workbooksource-checked
(x+y+z)^4\geq9\sum_{cyc}(x^3y+2x^2yz)$
Source: InternLM Lean-Workbook, record lean_workbook_9764 (Apache-2.0). Complete source proposition preserved; proof developed independently.
Preamble
import Mathlib open Real Nat
Formal statement
theorem WorkbookSource.base_9764 (x y z : ℝ) : (x + y + z) ^ 4 ≥ 9 * (x ^ 3 * y + 2 * x ^ 2 * y * z + y ^ 3 * z + 2 * y ^ 2 * z * x + z ^ 3 * x + 2 * z ^ 2 * x * y) := by sorry
Source