2022/03/10 by Alaoui, Ahmed El, Montanari, Andrea, Sellke, Mark · 23 citations
#Data Structures and Algorithms (cs.DS) #Disordered Systems and Neural Networks (cond-mat.dis-nn) #FOS: Computer and information sciences #FOS: Mathematics #FOS: Physical sciences #Probability (math.PR)
paper · doi:10.48550/arxiv.2203.05093
We consider the Sherrington-Kirkpatrick model of spin glasses at high-temperature and no external field, and study the problem of sampling from the Gibbs distribution μ in polynomial time. We prove that, for any inverse temperature β<1/2, there exists an algorithm with complexity O(n2) that samples from a distribution μalg which is close in normalized Wasserstein distance to μ. Namely, there exists a coupling of μ and μalg such that if (x,xalg)∈\-1,+1\n× \-1,+1\n is a pair drawn from this coupling, then n-1\mathbb E\||x-xalg||22\=on(1). The best previous results, by Bauerschmidt and Bodineau and by Eldan, Koehler, and Zeitouni, implied efficient algorithms to approximately sample (under a stronger metric) for β<1/4. We complement this result with a negative one, by introducing a suitable "stability" property for sampling algorithms, which is verified by many standard techniques. We prove that no stable algorithm can approximately sample for β>1, even under the normalized Wasserstein metric. Our sampling method is based on an algorithmic implementation of stochastic localization, which progressively tilts the measure μ towards a single configuration, together with an approximate message passing algorithm that is used to approximate the mean of the tilted measure.