Engineering an Efficient Probabilistic Exact Model Counter

Given a formula F , the problem of model counting, also known as #SAT, is to compute the number of satisfying assignments of F . While model counting has emerged as a crucial primitive in diverse domains from quantitative information flow analysis to neural network verification, scalability remains a fundamental challenge despite advances in both exact and approximate counting techniques. We present Ganak2, a novel framework that achieves substantial performance improvements through three key technical innovations: (1) refined residual formula processing incorporating SAT-specific techniques while maintaining seamless state transitions, (2) dual independent set framework maintaining distinct SAT-eligibility and decision sets, and (3) chronological backtracking specifically adapted to model counting. Our empirical evaluation on 1600 previous model counting competition instances demonstrates that Ganak2 successfully computes counts for 1121 instances within the one hour time limit, compared to 1032 instances by the prior state of the art approach, representing an 8.7% improvement. This progress is especially remarkable considering the extensive development and refinement of model counting tools over the years, driven by yearly competitive evaluation in the field.

‡ Note that the respective authors chose to capitalize sharpSAT and SharpSAT-TD differently.

‖ Note that AND gates are OR gates, with all inputs and the output negated. See De Morgan's laws [23]. Since we deal with literals, OR gates are sufficient to extract.