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Let G be a simple undirected connected graph. In this paper, new upper bounds on the distance Laplacian spectral radius of G are obtained. Moreover, new lower and upper bounds for the distance signless Laplacian spectral radius of G are…

Combinatorics · Mathematics 2019-06-14 Roberto C. Díaz , Ana I. Julio , Oscar Rojo

The distance-geometric graph representation adopts a unified scheme (distance) for representing the geometry of three-dimensional(3D) graphs. It is invariant to rotation and translation of the graph and it reflects pair-wise node…

Computer Vision and Pattern Recognition · Computer Science 2021-03-23 Daniel T. Chang

A graph is called normal if its vertex set can be covered by cliques and also by stable sets, such that every such clique and stable set have non-empty intersection. This notion is due to Korner, who introduced the class of normal graphs as…

Combinatorics · Mathematics 2013-06-25 Zsolt Patakfalvi

We investigate the behavior of electric potentials on distance-regular graphs, and extend some results of a prior paper. Our main result, Theorem 4, shows(together with Corollary 3) that if distance is measured by the electric resistance…

Combinatorics · Mathematics 2011-03-16 Jack Koolen , Greg Markowsky , Jongyook Park

The distance eigenvalues of a connected graph $G$ are the eigenvalues of its distance matrix $D(G)$. A graph is called distance integral if all of its distance eigenvalues are integers. Let $n \geq 3$ be an integer. A crown graph $Cr(n)$ is…

Combinatorics · Mathematics 2021-09-09 S. Morteza Mirafzal

In this paper, we define irregular bipolar fuzzy graphs and its various classifications. Size of regular bipolar fuzzy graphs is derived. The relation between highly and neighbourly irregular bipolar fuzzy graphs are established. Some basic…

Discrete Mathematics · Computer Science 2012-09-11 Sovan Samanta , Madhumangal Pal

For a distance-regular graph with second largest eigenvalue (resp. smallest eigenvalue) \mu1 (resp. \muD) we show that (\mu1+1)(\muD+1)<= -b1 holds, where equality only holds when the diameter equals two. Using this inequality we study…

Combinatorics · Mathematics 2010-04-08 Jack H. Koolen , Jongyook Park , Hyonju Yu

We give a brief survey of some known results on intrinsically linked or knotted graphs.

Geometric Topology · Mathematics 2020-06-15 Ramin Naimi

We consider nonregular graphs having precisely three distinct eigenvalues. The focus is mainly on the case of graphs having two distinct valencies and our results include constructions of new examples, structure theorems, valency…

Combinatorics · Mathematics 2016-05-03 Xi-Ming Cheng , Alexander L. Gavrilyuk , Gary R. W. Greaves , Jack H. Koolen

We study the inertia of distance matrices of weighted graphs. Our novel congruence-based proof of the inertia of weighted trees extends to a proof for the inertia of weighted unicyclic graphs whose cycle is a triangle. Partial results are…

Combinatorics · Mathematics 2023-04-26 Jeffrey Cheng , Ian Malcolm Johnson McInnis , Matthew Yee

The main goal of the paper is to characterize new classes of multicone graphs which are determined by both adjacency and Laplacian spectra. A multicone graph is defined to be the join of a clique and a regular graph. A wheel graph obtained…

Combinatorics · Mathematics 2018-03-02 Ali Zeydi Abdian

A powerful framework for studying graphs is to consider them as geometric graphs: nodes are randomly sampled from an underlying metric space, and any pair of nodes is connected if their distance is less than a specified neighborhood radius.…

Machine Learning · Computer Science 2022-11-28 Raffaele Paolino , Aleksandar Bojchevski , Stephan Günnemann , Gitta Kutyniok , Ron Levie

Strongly regular graphs are regular graphs with a constant number of common neighbours between adjacent vertices, and a constant number of common neighbours between non-adjacent vertices. These graphs have been of great interest over the…

Group Theory · Mathematics 2025-10-30 William H. Allen

A weakly distance-regular digraph is $P$-polynomial if its attached scheme is $P$-polynomial. In this paper, we characterize all $P$-polynomial weakly distance-regular digraphs.

Combinatorics · Mathematics 2023-06-28 Qing Zeng , Yuefeng Yang , Kaishun Wang

In this paper, we hope to bring closer graph theory and consensus algorithms. Firstly, we give a brief introduction to graph theory by listing a concise definition. Then we analyze and visualize some commonly used graphs. Secondly, we…

Discrete Mathematics · Computer Science 2021-01-27 Shen Zheng

We study the concept of the continuous mean distance of a weighted graph. For connected unweighted graphs, the mean distance can be defined as the arithmetic mean of the distances between all pairs of vertices. This parameter provides a…

Computational Geometry · Computer Science 2023-01-16 Delia Garijo , Alberto Márquez , Rodrigo I. Silveira

We analyze the distribution of the distance between two nodes, sampled uniformly at random, in digraphs generated via the directed configuration model, in the supercritical regime. Under the assumption that the covariance between the…

Probability · Mathematics 2017-04-24 Pim van der Hoorn , Mariana Olvera-Cravioto

Graphs are structured data that models complex relations between real-world entities. Heterophilic graphs, where linked nodes are prone to be with different labels or dissimilar features, have recently attracted significant attention and…

Social and Information Networks · Computer Science 2025-03-21 Chenghua Gong , Yao Cheng , Jianxiang Yu , Can Xu , Caihua Shan , Siqiang Luo , Xiang Li

In an earlier work, the author together with Guo [Hermitian adjacency matrix of digraphs and mixed graphs, J. Graph Theory 85 (2017) 217-248] introduced the Hermitian adjacency matrix of directed (and partially directed) graphs. However, it…

Combinatorics · Mathematics 2019-09-25 Bojan Mohar

Greb\'ik and Rocha [Fractional Isomorphism of Graphons, Combinatorica 42, pp 365-404 (2022)] extended the well studied notion of fractional isomorphism of graphs to graphons. We prove that fractionally isomorphic graphons can be…

Combinatorics · Mathematics 2023-09-22 Jan Hladký , Eng Keat Hng