## Abstract

We continue the discussion of the fermion models on graphs that started in the first paper of the series. Here we introduce a graphical gauge model (GGM) and show that: (a)it can be stated as an average/sum of a determinant defined on the graph over a (binary) gauge field; (b)it is equivalent to the monomer-dimer (MD) model on the graph; (c)the partition function of the model allows an explicit expression in terms of a series over disjoint directed cycles, where each term is a product of local contributions along the cycle and the determinant of a matrix defined on the remainder of the graph (excluding the cycle). We also establish a relation between the MD model on the graph and the determinant series, discussed in the first paper - however, considered using simple non-belief propagation choice of the gauge. We conclude with a discussion of possible analytic and algorithmic consequences of these results, as well as related questions and challenges.

Original language | English (US) |
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Article number | P12012 |

Journal | Journal of Statistical Mechanics: Theory and Experiment |

Volume | 2008 |

Issue number | 12 |

DOIs | |

State | Published - 2008 |

Externally published | Yes |

## Keywords

- Gauge theories
- Message-passing algorithms
- Rigorous results in statistical mechanics

## ASJC Scopus subject areas

- Statistical and Nonlinear Physics
- Statistics and Probability
- Statistics, Probability and Uncertainty