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In this paper, we define a class of auxiliary graphs associated with simple undirected graphs. This class of auxiliary graphs is based on the set of spanning trees of the original graph and the edges constituting those spanning trees. A…

Combinatorics · Mathematics 2019-02-26 Abhishek Garg , Mahipal Jadeja , Rahul Muthu

We introduce a new subclass of chordal graphs that generalizes split graphs, which we call well-partitioned chordal graphs. Split graphs are graphs that admit a partition of the vertex set into cliques that can be arranged in a star…

Combinatorics · Mathematics 2020-02-26 Jungho Ahn , Lars Jaffke , O-joung Kwon , Paloma T. Lima

A graph is chordal if it contains no induced cycle of length four or more. While finite chordal graphs are precisely those admitting tree-decompositions into cliques, this fails for infinite graphs. We establish two results extending the…

Combinatorics · Mathematics 2026-03-26 Max Pitz , Lucas Real , Roman Schaut

A graph property (i.e., a set of graphs) is induced-hereditary or additive if it is closed under taking induced-subgraphs or disjoint unions. If $\cP$ and $\cQ$ are properties, the product $\cP \circ \cQ$ consists of all graphs $G$ for…

Combinatorics · Mathematics 2007-05-23 A. Farrugia , R. Bruce Richter , G. Semanisin

For a fixed graph $H$ and for arbitrarily large host graphs $G$, the number of homomorphisms from $H$ to $G$ and the number of subgraphs isomorphic to $H$ contained in $G$ have been extensively studied in extremal graph theory and graph…

Combinatorics · Mathematics 2021-07-05 Chun-Hung Liu

We consider Colouring on graphs that are $H$-subgraph-free for some fixed graph $H$, which are graphs that do not contain $H$ as a subgraph. To classify the complexity of Colouring on $H$-subgraph-free graphs for connected $H$, it remains…

Combinatorics · Mathematics 2026-02-23 Tala Eagling-Vose , Jorik Jooken , Felicia Lucke , Barnaby Martin , Daniël Paulusma

We prove that a hereditary class of graphs is $(\mathsf{tw}, \omega)$-bounded if and only if the induced minors of the graphs from the class form a $(\mathsf{tw}, \omega)$-bounded class.

Combinatorics · Mathematics 2024-10-24 Claire Hilaire , Martin Milanič , Nicolas Trotignon , Djordje Vasić

This paper considers a hyperplane arrangement constructed with a subset of a set of all simple paths in a graph. A connection of the constructed arrangement to the maximum matching problem is established. Moreover, the problem of finding…

Combinatorics · Mathematics 2022-05-31 Aleksey Bolotnikov

Our main result is a full classification, for every connected graph $H$, of the computational complexity of Steiner Forest on $H$-subgraph-free graphs. To obtain this dichotomy, we establish the following new algorithmic, hardness, and…

In the companion paper [Linear rank-width of distance-hereditary graphs I. A polynomial-time algorithm, Algorithmica 78(1):342--377, 2017], we presented a characterization of the linear rank-width of distance-hereditary graphs, from which…

Combinatorics · Mathematics 2017-08-16 Mamadou Moustapha Kanté , O-joung Kwon

In this paper, we reveal an intriguing relationship between two seemingly unrelated notions: letter graphs and geometric grid classes of permutations. An important property common for both of them is well-quasi-orderability, implying, in a…

Combinatorics · Mathematics 2018-05-01 Bogdan Alecu , Vadim Lozin , Dominique de Werra , Viktor Zamaraev

We discuss a category of graphs, recursive clique trees, which have small-world and scale-free properties and allow a fine tuning of the clustering and the power-law exponent of their discrete degree distribution. We determine relevant…

Statistical Mechanics · Physics 2007-05-23 Francesc Comellas , Guillaume Fertin , André Raspaud

The implicit graph conjecture states that every sufficiently small, hereditary graph class has a labeling scheme with a polynomial-time computable label decoder. We approach this conjecture by investigating classes of label decoders defined…

Computational Complexity · Computer Science 2018-02-02 Maurice Chandoo

We describe the structure of those graphs that have largest spectral radius in the class of all connected graphs with a given degree sequence. We show that in such a graph the degree sequence is non-increasing with respect to an ordering of…

Combinatorics · Mathematics 2008-10-07 Tuerker Biyikoglu , Josef Leydold

We discover new hereditary classes of graphs that are minimal (with respect to set inclusion) of unbounded clique-width. The new examples include split permutation graphs and bichain graphs. Each of these classes is characterised by a…

Combinatorics · Mathematics 2023-01-31 A. Atminas , R. Brignall , V. Lozin , J. Stacho

A graph is said to be well-covered if all its maximal independent sets are of the same size. In 1999, Yamashita and Kameda introduced a subclass of well-covered graphs, called localizable graphs and defined as graphs having a partition of…

Combinatorics · Mathematics 2017-01-09 Ademir Hujdurović , Martin Milanič , Bernard Ries

Algorithms for node clustering typically focus on finding homophilous structure in graphs. That is, they find sets of similar nodes with many edges within, rather than across, the clusters. However, graphs often also exhibit heterophilous…

Machine Learning · Computer Science 2023-08-15 Sudhanshu Chanpuriya , Cameron Musco

We give a complete characterization of bipartite graphs having tree-like Galois lattices. We prove that the poset obtained by deleting bottom and top elements from the Galois lattice of a bipartite graph is tree-like if and only if the…

Discrete Mathematics · Computer Science 2014-06-03 Nicola Apollonio , Massimiliano Caramia , Paolo Giulio Franciosa

Mixture model-based frameworks are very popular for statistical inference in clustering. While convenient for producing probabilistic estimates of cluster assignments and uncertainty, they are prone to misspecification, which can lead to…

Statistics Theory · Mathematics 2026-05-15 Yu Zheng , Leo L. Duan , Arkaprava Roy

We examine indivisibility for classes of graphs. We show that the class of hereditarily $\alpha$-sparse graphs is indivisible if and only if $\alpha > 2$. Additionally, we show that the following classes of graphs are indivisible: perfect…

Combinatorics · Mathematics 2025-04-09 Vince Guingona , Felix Nusbaum , Zain Padamsee , Miriam Parnes , Christian Pippin , Ava Zinman
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