Formal verification of VGC checkpoint logic and zone lifecycle invariants

Develop formal verification proofs for the VGC 3-bit checkpoint logic and the R/G/B zone lifecycle invariants to establish correctness guarantees under concurrent execution, including race-freedom and proper reclamation behavior in highly parallel environments.

Background

VGC replaces per-object reference counting with a compact 3-bit checkpoint model and zone-based lifecycle management processed via logic gates. While benchmarks demonstrate performance benefits, formal correctness under concurrency is not established.

The authors explicitly call for formal verification to strengthen correctness guarantees, indicating that rigorous proofs of invariants and synchronization properties remain an open task.

References

Several directions remain open for future exploration. Formal verification of checkpoint logic and zone lifecycle invariants could strengthen correctness guaranties, especially in highly concurrent environments.

— VGC: A High-Performance Zone-Based Garbage Collector Architecture for Python with Partitioning and Parallel Execution  (2512.23768 - M, 29 Dec 2025) in Section Future Goals