AutoSAT: Automatically Optimize SAT Solvers via Large Language Models

Background: Conflict-Driven Clause Learning (CDCL) is a dominant framework for solving the Satisfiability problem (SAT). Modern CDCL solvers rely heavily on various heuristics, which significantly influence their performance. Established solvers such as MiniSat and Kissat typically incorporate multiple heuristics and therefore require substantial manual effort and domain expertise for fine-tuning in practice. Objectives: The emergence of Large Language Models (LLMs) offers a promising opportunity to automate SAT solver optimization. However, generating a complete CDCL solver from scratch using LLMs is impractical due to the complexity and large context volume of modern SAT solvers. To address this challenge, we propose AutoSAT, a framework that automatically optimizes heuristics within a CDCL solver, EasySAT. Our goal is to leverage LLMs to discover effective heuristic designs beyond conventional parameter tuning. Methods: Unlike traditional automated algorithm design approaches that mainly focus on hyperparameter tuning and operator selection, AutoSAT can generate new efficient heuristics for CDCL solvers. In this first attempt to leverage LLMs for SAT solver optimization, we integrate several search strategies, including the greedy hill climber and the (1 + 1) Evolutionary Algorithm, to guide LLMs in searching for better heuristics. Results: Experimental results demonstrate that LLMs can consistently enhance the performance of CDCL solvers. Empirically, AutoSAT outperforms MiniSat and its parameter-tuning variants on 12 of the 19 test datasets, and even surpasses the state-of-the-art hybrid solver Kissat and its parameter-tuning variants on 4 datasets. Conclusions: These results suggest that LLMs can serve as effective agents for automatically improving SAT solver heuristics. AutoSAT provides an initial step toward automated heuristic discovery for CDCL solvers, showing the potential of LLM-based methods to complement and reduce the manual expertise traditionally required in SAT solver design.