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Unmixed bipartite graphs have been characterized by Ravadra and Villarreal independently. Our aim in this paper is to characterize unmixed r-partite graphs under a certain condition, witch is a generalization of villarreal's theorem on…

Combinatorics · Mathematics 2015-11-03 Reza Jafarpoure Golzari , Rashid Zaare-Nahandi

We enumerate factorisations of the complete bipartite graph into spanning semiregular graphs in several cases, including when the degrees of all the factors except one or two are small. The resulting asymptotic behaviour is seen to…

Combinatorics · Mathematics 2022-12-21 Mahdieh Hasheminezhad , Brendan D. McKay

In this paper, we introduce a matrix for a mixed graph, called the integrated adjacency matrix. This matrix uniquely determines a mixed graph, as long as the indices of the matrix are specified. Additionally, we associate an (undirected)…

Combinatorics · Mathematics 2025-11-27 G. Kalaivani , R. Rajkumar

We formulate a spectral graph-partitioning algorithm that uses the two leading eigenvectors of the matrix corresponding to a selected quality function to split a network into three communities in a single step. In so doing, we extend the…

Data Analysis, Statistics and Probability · Physics 2009-09-24 Thomas Richardson , Peter J. Mucha , Mason A. Porter

The Unfriendly Partition Problem asks whether it is possible to split the vertex set of an infinite graph $G$ into two parts so that every vertex has at least as many neighbors in the other part than on its own. Despite the uncountable…

Combinatorics · Mathematics 2024-12-19 Leandro Fiorini Aurichi , Lucas Real

An undirected graph is said to have \emph{unique neighborhoods} if any two distinct nodes have also distinct sets of neighbors. In this way, the connections of a node to other nodes can characterize a node like an "identity", irrespectively…

Combinatorics · Mathematics 2025-05-13 Stefan Rass

We provide a criterion to distinguish two graphs which are indistinguishable by $2$-dimensional Weisfeiler-Lehman algorithm for almost all graphs. Haemers conjectured that almost all graphs are identified by their spectrum. Our approach…

Combinatorics · Mathematics 2025-11-21 Wei Wang , Da Zhao

Bipartite Graph is often a realistic model of complex networks where two different sets of entities are involved and relationship exist only two entities belonging to two different sets. Examples include the user-item relationship of a…

Social and Information Networks · Computer Science 2017-07-05 Suman Banerjee , Mamata Jenamani , Dilip Kumar Pratihar

A well--known fact in Spectral Graph Theory is the existence of pairs of isospectral nonisomorphic graphs (known as PINGS). The work of A.J. Schwenk (in 1973) and of C. Godsil and B. McKay (in 1982) shed some light on the explanation of the…

Combinatorics · Mathematics 2021-09-02 Francesco Belardo , Maurizio Brunetti , Matteo Cavaleri , Alfredo Donno

We present novel results related to isomorphic resonance graphs of 2-connected outerplane bipartite graphs. As the main result, we provide a structure characterization for 2-connected outerplane bipartite graphs with isomorphic resonance…

Combinatorics · Mathematics 2025-02-07 Simon Brezovnik , Zhongyuan Che , Niko Tratnik , Petra Žigert Pleteršek

We demonstrate how analysis of co-clustering in bipartite networks may be used as a bridge to connect, compare and complement clustering results about community structure in two different spaces: single-mode bipartite network projections.…

Digital Libraries · Computer Science 2020-03-24 Vasyl Palchykov , Yurij Holovatch

A signed graph is said to be sign-symmetric if it is switching isomorphic to its negation. Bipartite signed graphs are trivially sign-symmetric. We give new constructions of non-bipartite sign-symmetric signed graphs. Sign-symmetric signed…

Combinatorics · Mathematics 2020-03-24 Ebrahim Ghorbani , Willem H. Haemers , Hamid Reza Maimani , Leila Parsaei Majd

In this paper, we study a bipartite analogue of the `random graphs evolving by degrees' process. We are given a bipartitioned set of vertices $V$ into two disjoint parts ${L}$ and ${R}$ and possibly unequal positive constants $\alpha$ and…

Probability · Mathematics 2025-09-30 Neeladri Maitra

A hypergraph is said to be $1$-Sperner if for every two hyperedges the smallest of their two set differences is of size one. We present several applications of $1$-Sperner hypergraphs and their structure to graphs. In particular, we…

Combinatorics · Mathematics 2018-05-30 Endre Boros , Vladimir Gurvich , Martin Milanič

In this paper we consider bi-Cohen-Macaulay graphs, and give a complete classification of such graphs in the case they are bipartite or chordal. General bi-Cohen-Macaulay graphs are classified up to separation. The inseparable…

Commutative Algebra · Mathematics 2015-08-31 Jürgen Herzog , Ahad Rahimi

We completely determine the spectrum of an $I$-graph, that is, the eigenvalues of its adjacency matrix. We apply our result to prove known characterizations of connectedness and bipartiteness in $I$-graphs by using an spectral approach.…

Combinatorics · Mathematics 2015-11-12 Allana S. S. de Oliveira , Cybele T. M. Vinagre

This extended abstract introduces a class of graph learning applicable to cases where the underlying graph has polytopic uncertainty, i.e., the graph is not exactly known, but its parameters or properties vary within a known range. By…

Signal Processing · Electrical Eng. & Systems 2024-04-15 Masako Kishida , Shunsuke Ono

Graph-based subspace clustering methods have exhibited promising performance. However, they still suffer some of these drawbacks: encounter the expensive time overhead, fail in exploring the explicit clusters, and cannot generalize to…

Machine Learning · Computer Science 2021-02-23 Zhao Kang , Zhiping Lin , Xiaofeng Zhu , Wenbo Xu

We show that the independent set sequence of a bipartite graph need not be unimodal.

Combinatorics · Mathematics 2013-01-10 Arnab Bhattacharyya , Jeff Kahn

We present two hypermatrix formulations of the Cayley Hamilton theorem. One of the proposed formulation naturally extends to hypermatrices the combinatorial interpretations of the classical Cayley Hamilton theorem. We conclude by discussing…

Combinatorics · Mathematics 2015-03-18 Edinah K. Gnang