A Flexible Proof Format for SAT Solver-Elaborator Communication

TL;DR

FRAT is a new proof format for SAT solvers that reduces elaboration time and memory usage by allowing more detailed proofs, with an easy-to-parse, extensible design that balances implementation effort.

Contribution

The paper introduces FRAT, a flexible and efficient proof format for SAT solvers, improving upon DRAT with reduced computational costs and extensibility.

Findings

>84% median reduction in elaboration time

>94% median decrease in peak memory usage

Easy to parse and extensible proof format

Abstract

We introduce FRAT, a new proof format for unsatisfiable SAT problems, and its associated toolchain. Compared to DRAT, the FRAT format allows solvers to include more information in proofs to reduce the computational cost of subsequent elaboration to LRAT. The format is easy to parse forward and backward, and it is extensible to future proof methods. The provision of optional proof steps allows SAT solver developers to balance implementation effort against elaboration time, with little to no overhead on solver time. We benchmark our FRAT toolchain against a comparable DRAT toolchain and confirm >84% median reduction in elaboration time and >94% median decrease in peak memory usage.