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The Macaulay2 package GraphicalModels contains algorithms for the algebraic study of graphical models associated to undirected, directed and mixed graphs, and associated collections of conditional independence statements. Among the…

Commutative Algebra · Mathematics 2013-01-09 Luis David García-Puente , Sonja Petrović , Seth Sullivant

We present statistics on the decompositions (with respect to a distinguished symmetric 2t-cycle) of vertices of the hypercube graph, whose negative parts are covered by two subsets of the ground set {1,...,t} of the corresponding oriented…

Combinatorics · Mathematics 2023-03-24 Andrey O. Matveev

A tangle of order $k$ in a matroid or graph may be thought of as a "$k$-connected component". For a tangle of order $k$ in a matroid or graph that satisfies a certain robustness condition, we describe a tree decomposition of the matroid or…

Combinatorics · Mathematics 2011-09-07 Ben Clark , Geoff Whittle

Tropical curves in $\mathbb{R}^2$ correspond to metric planar graphs but not all planar graphs arise in this way. We describe several new classes of graphs which cannot occur. For instance, this yields a full combinatorial characterization…

Combinatorics · Mathematics 2021-08-03 Michael Joswig , Ayush Kumar Tewari

In the recent years we have witnessed a rapid development of new algorithmic techniques for parameterized algorithms for graph separation problems. We present experimental evaluation of two cornerstone theoretical results in this area:…

Data Structures and Algorithms · Computer Science 2018-11-20 Marcin Pilipczuk , Michał Ziobro

Computational topology is an area that revisits topological problems from an algorithmic point of view, and develops topological tools for improved algorithms. We survey results in computational topology that are concerned with graphs drawn…

Computational Geometry · Computer Science 2017-09-06 Éric Colin de Verdière

We study a notion of tropical linear series on metric graphs that combines two essential properties of tropicalizations of linear series on algebraic curves: the Baker-Norine rank and the independence rank. Our main results relate the local…

Algebraic Geometry · Mathematics 2025-09-05 Chih-Wei Chang , Matthew Dupraz , Hernan Iriarte , David Jensen , Dagan Karp , Sam Payne , Jidong Wang

We introduce torsoids, a canonical structure in matching covered graphs, corresponding to the bricks and braces of the graph. This allows a more fine-grained understanding of the structure of finite and infinite directed graphs with respect…

Combinatorics · Mathematics 2023-05-17 Nathan Bowler , Florian Gut , Meike Hatzel , Ken-ichi Kawarabayashi , Irene Muzi , Florian Reich

Vassiliev (finite type) invariants of knots can be described in terms of weight systems. These are functions on chord diagrams satisfying so-called 4-term relations. In the study of the sl2 weight system, it was shown that its value on a…

Combinatorics · Mathematics 2016-02-02 Sergey Lando , Vyacheslav Zhukov

In this paper we describe a physical problem, based on electromagnetic fields, whose topological constraints are higher dimensional versions of Kirchhoff's laws, involving $2-$ simplicial complexes embedded in $\mathbb{R} ^3$ rather than…

Combinatorics · Mathematics 2017-11-17 Hariharan Narayanan , H. Narayanan

Graph transformations definable in logic can be described using the notion of transductions. By understanding transductions as a basic embedding mechanism, which captures the possibility of encoding one graph in another graph by means of…

Combinatorics · Mathematics 2025-01-09 Michał Pilipczuk

Metric graphs are often introduced based on combinatorics, upon "associating" each edge of a graph with an interval; or else, casually "gluing" a collection of intervals at their endpoints in a network-like fashion. Here we propose an…

Combinatorics · Mathematics 2021-03-17 Delio Mugnolo

In this article, we propose a new type of square matrix associated with an undirected graph by trading off the naturally imbedded symmetry in them. The proposed matrix is defined using the neighbourhood sets of the vertices. It is called as…

Discrete Mathematics · Computer Science 2019-03-14 Sivakumar Karunakaran , Lavanya Selvaganesh

Homogeneous matroids are characterized by the property that strength equals fractional arboricity, and arise in the study of base modulus [22]. For graphic matroids, Cunningham [9] provided efficient algorithms for calculating graph…

Combinatorics · Mathematics 2024-08-02 Huy Truong , Pietro Poggi-Corradini

Bandelt and Mulder's structural characterization of Bipartite Distance Hereditary graphs asserts that such graphs can be built inductively starting from a single vertex and by repeatedly adding either pending vertices or twins (i.e.,…

Discrete Mathematics · Computer Science 2015-11-11 Nicola Apollonio , Massimiliano Caramia , Paolo Giulio Franciosa , Jean-François Mascari

An excluded minor characterization for the class of binary signed-graphic matroids with graphic cocircuits is provided. In this report we present the necessary computations for the case analysis in the proof.

Combinatorics · Mathematics 2012-05-07 Konstantinos Papalamprou , Leonidas Pitsoulis

We present a simplified exposition of some classical and modern results on graph drawings in the plane. These results are chosen so that they illustrate some spectacular recent higher-dimensional results on the border of topology and…

Geometric Topology · Mathematics 2020-12-23 A. Skopenkov

The arrow graph of a function consists of two parallel axes, with arrows from input values to output values. The lines through these arrows envelop a curve which we named the focal curve. This paper studies these focal curves in detail. We…

History and Overview · Mathematics 2025-11-26 Rogier Bos , Filip Cools

A categorical formalism for directed graphs is introduced, featuring natural notions of morphisms and subgraphs, and leading to two elementary descriptions of the free-properad monad, first in terms of presheaves on elementary graphs,…

Quantum Algebra · Mathematics 2016-10-04 Joachim Kock

Matrix Graph Grammars (MGG) is a novel approach to the study of graph dynamics ([15]). In the present contribution we look at MGG as a formal grammar and as a model of computation, which is a necessary step in the more ambitious program of…

Discrete Mathematics · Computer Science 2009-11-16 Pedro Pablo Perez Velasco