Title
Improved Strong Spatial Mixing for Colorings on Trees.
Abstract
Strong spatial mixing (SSM) is a form of correlation decay that has played an essential role in the design of approximate counting algorithms for spin systems. A notable example is the algorithm of Weitz (2006) for the hard-core model on weighted independent sets. We study SSM for the $q$-colorings problem on the infinite $(d+1)$-regular tree. Weak spatial mixing (WSM) captures whether the influence of the leaves on the root vanishes as the height of the tree grows. Jonasson (2002) established WSM when $q>d+1$. In contrast, in SSM, we first fix a coloring on a subset of internal vertices, and we again ask if the influence of the leaves on the root is vanishing. It was known that SSM holds on the $(d+1)$-regular tree when $q>\alpha d$ where $\alpha\approx 1.763...$ is a constant that has arisen in a variety of results concerning random colorings. Here we improve on this bound by showing SSM for $q>1.59d$. Our proof establishes an $L^2$ contraction for the BP operator. For the contraction we bound the norm of the BP Jacobian by exploiting combinatorial properties of the coloring of the tree.
Year
DOI
Venue
2019
10.4230/LIPIcs.APPROX-RANDOM.2019.48
APPROX-RANDOM
Field
DocType
Citations 
Combinatorics,Mathematics
Conference
0
PageRank 
References 
Authors
0.34
0
5
Name
Order
Citations
PageRank
Charilaos Efthymiou120915.44
andreas galanis26815.13
Thomas P. Hayes365954.21
Daniel Stefankovic424328.65
Eric Vigoda574776.55