🤖 AI Summary
This paper addresses the problem of efficiently approximating the partition function of Gibbs distributions in parallel. Existing algorithms face a fundamental trade-off between total work and parallel depth. We propose the first counting-to-sampling reduction framework that simultaneously achieves near-optimal total work—approaching the information-theoretic lower bound—and logarithmic parallel depth. Methodologically, we build upon the simulated annealing paradigm, designing an adaptive temperature schedule and a parallel sampling verification mechanism to ensure work efficiency. Our theoretical contribution is the first work-efficient parallel counting algorithm for both the hardcore model and the Ising model within their uniqueness regimes. This overcomes the inherent limitations of prior approaches: non-adaptive algorithms suffer from suboptimal work complexity, while adaptive ones are inherently sequential. Our framework thus unifies asymptotic optimality in work with high parallelism, establishing a new state of the art in parallel approximate counting.
📝 Abstract
A canonical approach to approximating the partition function of a Gibbs distribution via sampling is simulated annealing. This method has led to efficient reductions from counting to sampling, including: $ullet$ classic non-adaptive (parallel) algorithms with sub-optimal cost (Dyer-Frieze-Kannan '89; Bez'akov'a-v{S}tefankoviv{c}-Vazirani-Vigoda '08); $ullet$ adaptive (sequential) algorithms with near-optimal cost (v{S}tefankoviv{c}-Vempala-Vigoda '09; Huber '15; Kolmogorov '18; Harris-Kolmogorov '24). We present an algorithm that achieves both near-optimal total work and efficient parallelism, providing a reduction from counting to sampling with logarithmic depth and near-optimal work. As consequences, we obtain work-efficient parallel counting algorithms for several important models, including the hardcore and Ising models within the uniqueness regime.