A tree-decomposed transfer matrix for computing exact Potts model partition functions for arbitrary graphs, with applications to planar graph colouringsReportar como inadecuado




A tree-decomposed transfer matrix for computing exact Potts model partition functions for arbitrary graphs, with applications to planar graph colourings - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

1 INFN - Istituto Nazionale di Fisica Nucleare Milano 2 LPTENS - Laboratoire de Physique Théorique de l-ENS

Abstract : Combining tree decomposition and transfer matrix techniques provides a very general algorithm for computing exact partition functions of statistical models defined on arbitrary graphs. The algorithm is particularly efficient in the case of planar graphs. We illustrate it by computing the Potts model partition functions and chromatic polynomials the number of proper vertex colourings using Q colours for large samples of random planar graphs with up to N=100 vertices. In the latter case, our algorithm yields a sub-exponential average running time of ~ exp1.516 sqrtN, a substantial improvement over the exponential running time ~ exp0.245 N provided by the hitherto best known algorithm. We study the statistics of chromatic roots of random planar graphs in some detail, comparing the findings with results for finite pieces of a regular lattice.

Keywords : computational complexity transfer matrix tree decomposition chromatic polynomial





Autor: Andrea Bedini - Jesper Jacobsen -

Fuente: https://hal.archives-ouvertes.fr/



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