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We study a model in which p independent Ising spins are coupled to 2d quantum gravity (in the form of dynamical planar phi-cubed graphs). Consideration is given to the p tends to infinity limit in which the partition function becomes…

High Energy Physics - Theory · Physics 2009-10-28 M. G. Harris , J. F. Wheater

This paper proposes a two-level restricted additive Schwarz (RAS) method for multiscale PDEs, built on top of a multiscale spectral generalized finite element method (MS-GFEM). The method uses coarse spaces constructed from optimal local…

Numerical Analysis · Mathematics 2024-08-30 Arne Strehlow , Chupeng Ma , Robert Scheichl

We review some aspects of the fermionic interpretation of the two-dimensional Ising model. The use is made of the notion of the integral over the anticommuting Grassmann variables. For simple and more complicated 2D Ising lattices, the…

Statistical Mechanics · Physics 2007-05-23 V. N. Plechko

The problem of (approximately) counting the independent sets of a bipartite graph (#BIS) is the canonical approximate counting problem that is complete in the intermediate complexity class #RH\Pi_1. It is believed that #BIS does not have an…

Computational Complexity · Computer Science 2019-07-16 Radu Curticapean , Holger Dell , Fedor Fomin , Leslie Ann Goldberg , John Lapinskas

We investigate a relaxation of the notion of fractional treewidth-fragility, namely fractional tree-independence-number-fragility. In particular, we obtain polynomial-time approximation schemes for meta-problems such as finding a…

Data Structures and Algorithms · Computer Science 2025-04-23 Esther Galby , Andrea Munaro , Shizhou Yang

We show for a broad class of counting problems, correlation decay (strong spatial mixing) implies FPTAS on planar graphs. The framework for the counting problems considered by us is the Holant problems with arbitrary constant-size domain…

Data Structures and Algorithms · Computer Science 2012-07-17 Yitong Yin , Chihao Zhang

In this paper the exact solution and correlation functions for a double-chain Ising model with multi-spin interactions and symmetric Hamiltonian density are obtained. The study employs the transfer matrix method to derive fundamental…

Statistical Mechanics · Physics 2025-11-21 Pavel Khrapov , Stepan Shchurenkov

The emergence of massive graph data sets requires fast mining algorithms. Centrality measures to identify important vertices belong to the most popular analysis methods in graph mining. A measure that is gaining attention is forest…

Data Structures and Algorithms · Computer Science 2021-01-18 Alexander van der Grinten , Eugenio Angriman , Maria Predari , Henning Meyerhenke

We study the approximation complexity of the partition function of the eight-vertex model on general 4-regular graphs. For the first time, we relate the approximability of the eight-vertex model to the complexity of approximately counting…

Computational Complexity · Computer Science 2019-04-25 Jin-Yi Cai , Tianyu Liu

This paper deals with the partition function of the Ising model from statistical mechanics, which is used to study phase transitions in physical systems. A special case of interest is that of the Ising model with constant energies and…

Computational Complexity · Computer Science 2012-10-15 Tomer Kotek

We give a deterministic algorithm for approximately counting satisfying assignments of a degree-$d$ polynomial threshold function (PTF). Given a degree-$d$ input polynomial $p(x_1,\dots,x_n)$ over $R^n$ and a parameter $\epsilon> 0$, our…

Computational Complexity · Computer Science 2013-12-02 Anindya De , Rocco Servedio

We present a deterministic way of assigning small (log bit) weights to the edges of a bipartite planar graph so that the minimum weight perfect matching becomes unique. The isolation lemma as described in (Mulmuley et al. 1987) achieves the…

Data Structures and Algorithms · Computer Science 2008-02-21 Samir Datta , Raghav Kulkarni , Sambuddha Roy

The present work deals with active sampling of graph nodes representing training data for binary classification. The graph may be given or constructed using similarity measures among nodal features. Leveraging the graph for classification…

Machine Learning · Statistics 2018-10-17 Dimitris Berberidis , Georgios B. Giannakis

In this paper, we propose and study a new semi-random model for graph partitioning problems. We believe that it captures many properties of real--world instances. The model is more flexible than the semi-random model of Feige and Kilian and…

Data Structures and Algorithms · Computer Science 2015-03-20 Konstantin Makarychev , Yury Makarychev , Aravindan Vijayaraghavan

We explore connections between the phenomenon of correlation decay and the location of Lee-Yang and Fisher zeros for various spin systems. In particular we show that, in many instances, proofs showing that weak spatial mixing on the Bethe…

Computational Complexity · Computer Science 2022-08-05 Jingcheng Liu , Alistair Sinclair , Piyush Srivastava

The statistics of critical spin-spin correlation functions in Ising systems with non-frustrated disorder are investigated on a strip geometry, via numerical transfer-matrix techniques. Conformal invariance concepts are used, in order to…

Statistical Mechanics · Physics 2007-05-23 Jean C. Lessa , S. L. A. de Queiroz

Given a connected vertex-weighted graph $G$, the maximum weight internal spanning tree (MaxwIST) problem asks for a spanning tree of $G$ that maximizes the total weight of internal nodes. This problem is NP-hard and APX-hard, with the…

Data Structures and Algorithms · Computer Science 2020-06-24 Ahmad Biniaz

We present a randomized algorithm for generating standard set-valued tableaux by extending the Green-Nijenhuis-Wilf hook walk algorithm. In the case of asymptotically rank two partitions, we use this algorithm to give a fully polynomial…

Combinatorics · Mathematics 2021-08-31 Reuven Hodges , Gidon Orelowitz

Physics-Informed Neural Networks (PINNs) are mesh-free approaches for the numerical approximation of partial differential equations, where a neural network is trained by minimizing a loss function derived from the governing equations and…

Numerical Analysis · Mathematics 2026-04-03 Medard Govoeyi , Thomas Richter

This paper introduces the \emph{$d$-distance matching problem}, in which we are given a bipartite graph $G=(S,T;E)$ with $S=\{s_1,\dots,s_n\}$, a weight function on the edges and an integer $d\in\mathbb Z_+$. The goal is to find a maximum…

Combinatorics · Mathematics 2023-01-24 Péter Madarasi