2004/04/26 by M. Freedman, Michael Freedman, Freedman, M. +6 · 3 citations
Mathematics · Physics and Astronomy · #05C99 (Primary) #82B99 (Secondary) #Combinatorics (math.CO) #FOS: Mathematics #FOS: Physical sciences #Graph theory and applications #Markov Chains and Monte Carlo Methods #Mathematical Physics (math-ph) #Random Matrices and Applications #math-ph #math.CO #math.MP #msc:05C99 #msc:82B99
paper · pdf · doi:10.48550/arxiv.math/0404468
17 pages Latex
arxiv created 2004/04/26 · openalex publication_date 2004/04/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
It is shown that a graph parameter can be realized as the number of homomorphisms into a fixed (weighted) graph if and only if it satisfies two linear algebraic conditions: reflection positivity and exponential rank-connectivity. In terms of statistical physics, this can be viewed as a characterization of partition functions of vertex models.