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The Fundamental Morphism Theorem is a categorical version of the First Noether Isomorphism Theorem for categories that do not have kernels or cokernels. We consider two categories of graphs. Both categories will admit graphs with multiple…

Combinatorics · Mathematics 2018-08-31 Tien Chih , Demitri Plessas

We study isospectrality for mixed Dirichlet-Neumann boundary conditions, and extend the previously derived graph-theoretic formulation of the transplantation method. Led by the theory of Brownian motion, we introduce vertex-colored and…

Spectral Theory · Mathematics 2015-04-14 Peter Herbrich

In this paper we discuss reconstruction problems for graphs. We develop some new ideas like isomorphic extension of isomorphic graphs, partitioning of vertex sets into sets of equivalent points, subdeck property, etc. and develop an…

General Mathematics · Mathematics 2011-10-21 Dhananjay P. Mehendale

This paper proposes a novel representation of decomposable graphs based on semi-latent tree-dependent bipartite graphs. The novel representation has two main benefits. First, it enables a form of sub-clustering within maximal cliques of the…

Methodology · Statistics 2017-12-05 Mohamad Elmasri

Graph decompositions are the natural generalisation of tree decompositions where the decomposition tree is replaced by a genuine graph. Recently they found theoretical applications in the theory of sparsity, topological graph theory,…

Discrete Mathematics · Computer Science 2023-12-20 Johannes Carmesin , Sarah Frenkel

Graphs and networks play an important role in modeling and analyzing complex interconnected systems such as transportation networks, integrated circuits, power grids, citation graphs, and biological and artificial neural networks. Graph…

Machine Learning · Statistics 2024-02-15 Stefan Klus , Maia Trower

We are concerned with split graphs and pseudo-split graphs whose complements are isomorphic to themselves. These special subclasses of self-complementary graphs are actually the core of self-complementary graphs. Indeed, we show that all…

Combinatorics · Mathematics 2023-12-19 Yixin Cao , Haowei Chen , Shenghua Wang

It is known that a graph isomorphism testing algorithm is polynomially equivalent to a detecting of a graph non-trivial automorphism algorithm. The polynomiality of the latter algorithm, is obtained by consideration of symmetry properties…

General Mathematics · Mathematics 2007-05-23 Aleksandr Golubchik

The fractional and circular chromatic numbers are the two most studied non-integral refinements of the chromatic number of a graph. Starting from the definition of a coloring base of a graph, which originated in work related to ergodic…

Combinatorics · Mathematics 2021-01-12 Pablo Candela , Carlos Catala , Robert Hancock , Adam Kabela , Daniel Kral , Ander Lamaison , Lluis Vena

Multilevel modeling extends traditional modeling techniques with a potentially unlimited number of abstraction levels. Multilevel models can be formally represented by multilevel typed graphs whose manipulation and transformation are…

Software Engineering · Computer Science 2020-06-26 Uwe Wolter , Fernando Macías , Adrian Rutle

Extending a classic result of Johnson and Newman, this paper provides a matrix characterization for two generalized cospectral graphs with a pair of generalized cospectral vertex-deleted subgraphs. As an application, we present a new…

Combinatorics · Mathematics 2024-08-06 Wei Wang , Wenqiang Wen , Songlin Guo

We construct tree-decompositions of graphs that distinguish all their k-blocks and tangles of order k, for any fixed integer k. We describe a family of algorithms to construct such decompositions, seeking to maximize their diversity subject…

Combinatorics · Mathematics 2014-04-25 Johannes Carmesin , Reinhard Diestel , Matthias Hamann , Fabian Hundertmark

We investigate the relationship between the structure of a discrete graphical model and the support of the inverse of a generalized covariance matrix. We show that for certain graph structures, the support of the inverse covariance matrix…

Machine Learning · Statistics 2014-01-07 Po-Ling Loh , Martin J. Wainwright

We strengthen and put in a broader perspective previous results of the first two authors on colliding permutations. The key to the present approach is a new non-asymptotic invariant for graphs.

Combinatorics · Mathematics 2007-09-28 János Körner , Claudia Malvenuto , Gábor Simonyi

In this paper we focus on the problem of finding (small) subhypergraphs in a (large) hypergraph. We use this problem to illustrate that reducing hypergraph problems to graph problems by working with the 2-section is not always a reasonable…

We prove that for every pair of quantum isomorphic graphs, their block trees and their block graphs are isomorphic, and that such an isomorphism can be chosen so that the corresponding blocks are quantum isomorphic -- in particular,…

Combinatorics · Mathematics 2025-10-23 Amaury Freslon , Paul Meunier , Pegah Pournajafi

We consider complete graphs with edge weights and/or node weights taking values in some set. In the first part of this paper, we show that a large number of graphs are completely determined, up to isomorphism, by the distribution of their…

Combinatorics · Mathematics 2007-10-11 Mireille Boutin , Gregor Kemper

Homomorphically full graphs are those for which every homomorphic image is isomorphic to a subgraph. We extend the definition of homomorphically full to oriented graphs in two different ways. For the first of these, we show that…

Discrete Mathematics · Computer Science 2024-02-14 Thomas Bellitto , Christopher Duffy , Gary MacGillivray

This paper uses the theory of covering graphs to characterize some of the edge-transitive graphs which can arise as token graphs.

Combinatorics · Mathematics 2025-05-28 Sergio G. Gómez-Galicia , Octavio B. Zapata-Fonseca

We develop a homotopical variant of the classic notion of an algebraic theory as a tool for producing deformations of homotopy theories. From this, we extract a framework for constructing and reasoning with obstruction theories and spectral…

Algebraic Topology · Mathematics 2025-08-13 William Balderrama