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A divisible design graph is a graph whose adjacency matrix is an incidence matrix of a (group) divisible design. Divisible design graphs were introduced in 2011 as a generalization of $(v,k,\lambda)$-graphs. Here we describe four new…

Combinatorics · Mathematics 2024-04-16 Bart De Bruyn , Sergey Goryainov , Willem Haemers , Leonid Shalaginov

We define the notions of Reidemeister torsion and analytic torsion for directed graphs by means of the path homology theory introduced by the authors in \cite{Grigoryan-Lin-Muranov-Yau2013, Grigoryan-Lin-Muranov-Yau2014,…

Combinatorics · Mathematics 2020-12-15 Alexander Grigor'yan , Yong Lin , Shing-Tung Yau

Nonstandard graphs have been defined and examined in prior works. The present work does the same for nonstandard digraphs. Since digraphs have more structure than do graphs, the present discussion requires more complicated definitions and…

Combinatorics · Mathematics 2009-04-28 A. H. Zemanian

We present a construction of Neumaier graphs with nexus 1, which generalises two known constructions of Neumaier graphs. We also use W. Wang, L. Qiu, and Y. Hu switching to show that we construct cospectral Neumaier graphs. Finally, we show…

Combinatorics · Mathematics 2023-02-14 Rhys J. Evans , Sergey Goryainov , Elena V. Konstantinova , Alexander D. Mednykh

Directed graphs (DG), interpreted as state transition diagrams, are traditionally used to represent finite-state automata (FSA). In the context of formal languages, both FSA and regular expressions (RE) are equivalent in that they accept…

Formal Languages and Automata Theory · Computer Science 2009-07-30 Fevzi Belli , Mutlu Beyazit

Recently, one has seen a surge of interest in developing such methods including ones for learning such representations for (undirected) graphs (while preserving important properties). However, most of the work to date on embedding graphs…

Social and Information Networks · Computer Science 2018-11-30 Jiankai Sun , Srinivasan Parthasarathy

Directed mixed graphs permit directed and bidirected edges between any two vertices. They were first considered in the path analysis developed by Sewall Wright and play an essential role in statistical modeling. We introduce a matrix…

Statistics Theory · Mathematics 2024-07-23 Qingyuan Zhao

In this paper, we investigate the connectivity of friends-and-strangers graphs, which were introduced by Defant and Kravitz in 2020. We begin by considering friends-and-strangers graphs arising from two random graphs and consider the…

Combinatorics · Mathematics 2023-09-08 Aleksa Milojevic

We introduce and study analogues of expander and hyperfinite graph sequences in the context of directed acyclic graphs, which we call "extender" and "hypershallow" graph sequences, respectively. Our main result is a probabilistic…

Combinatorics · Mathematics 2023-06-22 Endre Csóka , Łukasz Grabowski

We describe two constructions of (very) dense graphs which are edge disjoint unions of large {\em induced} matchings. The first construction exhibits graphs on $N$ vertices with ${N \choose 2}-o(N^2)$ edges, which can be decomposed into…

Combinatorics · Mathematics 2011-11-09 Noga Alon , Ankur Moitra , Benny Sudakov

Rough graph is the graphical structure of information system with imprecise knowledge. Tong He designed the properties of rough graph in 2006[6] and following that He and Shi introduced the notion of edge rough graph[7]. He et al developed…

Artificial Intelligence · Computer Science 2022-08-26 R. Nithya , K. Anitha

In this paper we introduce new generalizations of the zeta function, the Tricomi functions; their main properties are studied. This opens the way to a deeper, better application of these functions both in the theory of special functions,…

Classical Analysis and ODEs · Mathematics 2018-01-01 N. Virchenko , A. Ponomarenko

The concept of directed strongly regular graphs (DSRG) was introduced by Duval in 1988 \cite{A}.In the present paper,we use representation theory of finite groups in order to investigate the directed strongly regular Cayley graphs.We first…

Combinatorics · Mathematics 2018-05-28 Yiqin He , Bicheng Zhang

In this paper, we present formulas for the edge zeta function and the second weighted zeta function with respect to the group matrix of a finite abelian group $\Gamma $. Furthermore, we give another proof of Dedekind Theorem for the group…

Combinatorics · Mathematics 2025-03-24 Tsuyoshi Miezaki , Iwao Sato

In this paper, we introduce the notion of two-way $(t,\lambda)$-liking digraphs as a way to extend the results for generalized friendship graphs. A two-way $(t,\lambda)$-liking digraph is a digraph in which every $t$ vertices have exactly…

Combinatorics · Mathematics 2024-05-24 Hojin Chu , Suh-Ryung Kim

Directed graphs have long been used to gain understanding of the structure of semigroups, and recently the structure of directed graph semigroups has been investigated resulting in a characterization theorem and an analog of Fruct's…

Combinatorics · Mathematics 2015-06-09 Tien Chih , Demitri Plessas

In this note we present a general approach to construct large digraphs from small ones. These are called expanded digraphs, and, as particular cases, we show the close relationship between lifted digraphs of voltage digraphs and line…

Combinatorics · Mathematics 2016-10-04 C. Dalfó , M. A. Fiol , M. Miller , J. Ryan

In this study, we challenge the traditional approach of frequency analysis on directed graphs, which typically relies on a single measure of signal variation such as total variation. We argue that the inherent directionality in directed…

Signal Processing · Electrical Eng. & Systems 2024-01-17 Semin Kwak , Laura Shimabukuro , Antonio Ortega

To deal with irregular data structure, graph convolution neural networks have been developed by a lot of data scientists. However, data scientists just have concentrated primarily on developing deep neural network method for un-directed…

Machine Learning · Statistics 2022-09-07 Loc Hoang Tran , Linh Hoang Tran

In this paper, we introduce a new model to study network reliability with node failures. This model, strongly connected node reliability, is the directed variant of node reliability and measures the probability that the operational vertices…

Combinatorics · Mathematics 2022-06-27 Danielle Cox , Kyle MacKeigan , Emily Wright