{ "id": "1210.4232", "version": "v1", "published": "2012-10-16T02:32:12.000Z", "updated": "2012-10-16T02:32:12.000Z", "title": "Phase coexistence and torpid mixing in the 3-coloring model on Z^d", "authors": [ "David Galvin", "Jeff Kahn", "Dana Randall", "Gregory Sorkin" ], "comment": "26 pages. arXiv admin note: substantial text overlap with arXiv:1206.3193", "categories": [ "math.CO", "math-ph", "math.MP" ], "abstract": "We show that for all sufficiently large d, the uniform proper 3-coloring model (in physics called the 3-state antiferromagnetic Potts model at zero temperature) on Z^d admits multiple maximal-entropy Gibbs measures. This is a consequence of the following combinatorial result: if a proper 3-coloring is chosen uniformly from a box in Z^d, conditioned on color 0 being given to all the vertices on the boundary of the box which are at an odd distance from a fixed vertex v in the box, then the probability that v gets color 0 is exponentially small in d. The proof proceeds through an analysis of a certain type of cutset separating v from the boundary of the box, and builds on techniques developed by Galvin and Kahn in their proof of phase transition in the hard-core model on Z^d. Building further on these techniques, we study local Markov chains for sampling proper 3-colorings of the discrete torus Z^d_n. We show that there is a constant \\rho \\approx 0.22 such that for all even n \\geq 4 and d sufficiently large, if M is a Markov chain on the set of proper 3-colorings of Z^d_n that updates the color of at most \\rho n^d vertices at each step and whose stationary distribution is uniform, then the mixing time of M (the time taken for M to reach a distribution that is close to uniform, starting from an arbitrary coloring) is essentially exponential in n^{d-1}.", "revisions": [ { "version": "v1", "updated": "2012-10-16T02:32:12.000Z" } ], "analyses": { "subjects": [ "05C15", "82B20" ], "keywords": [ "phase coexistence", "torpid mixing", "admits multiple maximal-entropy gibbs measures", "study local markov chains", "antiferromagnetic potts model" ], "note": { "typesetting": "TeX", "pages": 26, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2012arXiv1210.4232G" } } }