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This paper studies induced paths in strongly regular graphs. We give an elementary proof that a strongly regular graph contains a path $P_4$ as an induced subgraph if and only if it is primitive, i.e. it is neither a complete multipartite…

Combinatorics · Mathematics 2023-07-28 Robert F. Bailey , Abigail K. Rowsell

We use the line digraph construction to associate an orthogonal matrix with each graph. From this orthogonal matrix, we derive two further matrices. The spectrum of each of these three matrices is considered as a graph invariant. For the…

Quantum Physics · Physics 2007-05-23 David Emms , Edwin R. Hancock , Simone Severini , Richard C. Wilson

We present an improved algorithm for computing the $4$-edge-connected components of an undirected graph in linear time. The new algorithm uses only elementary data structures, and it is simple to describe and to implement in the pointer…

Data Structures and Algorithms · Computer Science 2021-08-20 Loukas Georgiadis , Giuseppe F. Italiano , Evangelos Kosinas

We introduce a new notation for representing labeled regular bipartite graphs of arbitrary degree. Several enumeration problems for labeled and unlabeled regular bipartite graphs have been introduced. A general algorithm for enumerating all…

Discrete Mathematics · Computer Science 2015-12-31 Vivek S. Nittoor

Let $F$ and $G$ be simple finite oriented graphs (without symmetric arcs). A graph $G$ is called $F$-irregular if any two distinct vertices in $G$ belong to a different number of subgraphs of $G$ isomorphic to $F$. In this paper, we…

Combinatorics · Mathematics 2026-05-22 Tatiana Dovzhenok , Ilya Lukashenko , Yahor Filiuta

The aim of this paper is to derive on the basis of the Euler's formula several analytical relations which hold for certain classes of planar graphs and which can be useful in algorithmic graph theory.

Discrete Mathematics · Computer Science 2012-07-11 Armen Bagdasaryan

We give a necessary and sufficient graph-theoretic characterization of toric ideals of graphs that are unimodular. As a direct consequence, we provide the structure of unimodular graphs by proving that the incidence matrix of a graph $G$ is…

Commutative Algebra · Mathematics 2025-10-15 Christos Tatakis

In this paper, we survey results regarding the interlace polynomial of a graph, connections to such graph polynomials as the Martin and Tutte polynomials, and generalizations to the realms of isotropic systems and delta-matroids.

Combinatorics · Mathematics 2016-01-13 Ada Morse

We elaborate on the connection between Gel'fand-Kapranov-Zelevinsky systems, de Rham theory for twisted cohomology groups, and Pfaffian equations for Feynman integrals. We propose a novel, more efficient algorithm to compute Macaulay…

In the present paper, we study Neumaier Cayley graphs. First, we give a criterion for a Cayley graph to be a Neumaier graph with a spread given by the cosets of a subgroup. Further, we construct a new infinite family of Neumaier Cayley…

Combinatorics · Mathematics 2026-02-24 Rhys J. Evans , Sergey Goryainov , Grigory Ryabov , Da Zhao

Learning faithful graph representations as sets of vertex embeddings has become a fundamental intermediary step in a wide range of machine learning applications. We propose the systematic use of symmetric spaces in representation learning,…

Machine Learning · Computer Science 2021-06-10 Federico López , Beatrice Pozzetti , Steve Trettel , Michael Strube , Anna Wienhard

Recently, Braunstein et al. [1] introduced normalized Laplacian matrices of graphs as density matrices in quantum mechanics and studied the relationships between quantum physical properties and graph theoretical properties of the underlying…

Quantum Physics · Physics 2011-11-15 Chai Wah Wu

In 2010, Butler introduced the unfolding operation on a bipartite graph to produce two bipartite graphs, which are cospectral for the adjacency and the normalized Laplacian matrices. In this article, we describe how the idea of unfolding a…

Combinatorics · Mathematics 2024-11-22 M. Rajesh Kannan , Shivaramakrishna Pragada , Hitesh Wankhede

This work deals with the generation of theoretical correlation matrices with specific sparsity patterns, associated to graph structures. We present a novel approach based on convex optimization, offering greater flexibility compared to…

Signal Processing · Electrical Eng. & Systems 2025-09-03 Ali Fahkar , Kévin Polisano , Irène Gannaz , Sophie Achard

In this paper, we introduce a graph matching method that can account for constraints of arbitrary order, with arbitrary potential functions. Unlike previous decomposition approaches that rely on the graph structures, we introduce a…

Computer Vision and Pattern Recognition · Computer Science 2018-02-26 D. Khuê Lê-Huu , Nikos Paragios

We study entanglement properties of mixed density matrices obtained from combinatorial Laplacians. This is done by introducing the notion of the density matrix of a graph. We characterize the graphs with pure density matrices and show that…

Quantum Physics · Physics 2007-05-23 Samuel L. Braunstein , Sibasish Ghosh , Simone Severini

Graph symmetries intervene in diverse applications, from enumeration, to graph structure compression, to the discovery of graph dynamics (e.g., node arrival order inference). Whereas Erd\H{o}s-R\'enyi graphs are typically asymmetric, real…

Probability · Mathematics 2018-12-27 Tomasz Luczak , Abram Magner , Wojciech Szpankowski

For a graph $G=(V,E),$ a matching $M$ is a set of independent edges. The topic of matchings is well studied in graph theory. In this paper many varieties of matchings are discussed.

Combinatorics · Mathematics 2018-05-10 Todd Fenstermacher , Soumendra Ganguly , Stephen Hedetniemi , Renu Laskar

Design patterns being applied more and more to solve the software engineering difficulties in the object oriented software design procedures. So, the design pattern detection is widely used by software industries. Currently, many solutions…

Software Engineering · Computer Science 2014-08-27 Afnan Salem Ba-Brahem , M. Rizwan Jameel Qureshi

Fix $c\in (0,1)$ and let $\Gamma$ be a $\lfloor c n\rfloor$-regular digraph on $n$ vertices drawn uniformly at random. We prove that when $n$ is large, the (non-symmetric) adjacency matrix $M$ of $\Gamma$ is invertible with high…

Probability · Mathematics 2015-08-04 Nicholas A. Cook