oxiz-proof

Proof generation and checking for the OxiZ SMT solver.

Overview

This crate provides machine-checkable proof output, enabling verification of solver results by external proof checkers. This is a beyond Z3 feature - while Z3 supports generic proofs, OxiZ aims to generate standardized, machine-checkable proofs by default.

Supported Formats

Why Machine-Checkable Proofs?

• Trust: Independent verification of solver correctness
• Certification: Required for safety-critical applications
• Debugging: Identify bugs in solver implementation
• Interoperability: Exchange proofs between tools

Usage

use oxiz_proof::{Proof, ProofStep};

// Proofs are generated automatically during solving
let proof: Proof = solver.get_proof();

// Output in different formats
println!("{}", proof.to_drat());
println!("{}", proof.to_alethe());

SMT-LIB2 Integration

(set-option :produce-proofs true)
(assert (and p (not p)))
(check-sat)  ; Returns UNSAT
(get-proof)  ; Returns proof tree

Proof Structure

(step t1 (cl (not p) q) :rule resolution :premises (t0))
(step t2 (cl (not q) r) :rule unit_resolution :premises (t1 h1))
(step t3 (cl false) :rule false_rule :premises (t2))

References

• Barbosa, H., et al. (2022). Flexible proof production in an industrial-strength SMT solver. IJCAR.
• Wetzler, N., Heule, M., & Hunt, W. (2014). DRAT-trim: Efficient checking and trimming using expressive clausal proofs. SAT.

License

MIT OR Apache-2.0