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Blokhuis showed that all maximum cliques in Paley graphs of square order have a subfield structure. Recently, it has been shown that in Peisert-type graphs, all maximum cliques are affine subspaces, and yet some maximum cliques do not arise…

Combinatorics · Mathematics 2024-08-16 Shamil Asgarli , Chi Hoi Yip

2-quasi best match graphs (2-qBMGs) are directed graphs that capture a notion of close relatedness in phylogenetics. Here, we investigate the undirected underlying graph of a 2-qBMG (un-2qBMG) and show that they contain neither a path $P_l$…

Combinatorics · Mathematics 2025-12-08 Annachiara Korchmaros , Peter F. Stadler

This paper continues a series of papers investigating the following question: which hereditary graph classes have bounded treewidth? We call a graph $t$-clean if it does not contain as an induced subgraph the complete graph $K_t$, the…

Combinatorics · Mathematics 2024-09-05 Tara Abrishami , Maria Chudnovsky , Sepehr Hajebi , Sophie Spirkl

A simple graph G is k-ordered (respectively, k-ordered hamiltonian) if, for any sequence of k distinct vertices v_1, ..., v_k of G, there exists a cycle (respectively, a hamiltonian cycle) in G containing these k vertices in the specified…

Combinatorics · Mathematics 2007-05-23 Karola Meszaros

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

We generalize the notion of quasirandom which concerns a class of equivalent properties that random graphs satisfy. We show that the convergence of a graph sequence under the spectral distance is equivalent to the convergence using the…

Combinatorics · Mathematics 2013-11-06 Fan Chung

An ordered graph is a graph with a total order over its vertices. A linear layout of an ordered graph is a partition of the edges into sets of either non-crossing edges, called stacks, or non-nesting edges, called queues. The stack (queue)…

Discrete Mathematics · Computer Science 2024-12-18 Deborah Haun , Laura Merker , Sergey Pupyrev

Suppose that $G$ is a graph of cardinality $\mu^+$ with chromatic number $\chi(G)\geq \mu^+$. One possible reason that this could happen is if $G$ contains a clique of size $\mu^+$. We prove that this is indeed the case when the edge…

Logic · Mathematics 2025-11-12 Yatir Halevi , Itay Kaplan , Saharon Shelah

An ordering of the vertices of a graph is \emph{connected} if every vertex (but the first) has a neighbor among its predecessors. The greedy colouring algorithm of a graph with a connected order consists in taking the vertices in order, and…

Discrete Mathematics · Computer Science 2018-06-08 Ngoc Khang Le , Nicolas Trotignon

Man\v{c}inska and Roberson introduced quantum graph homomorphisms as the existence of perfect quantum strategies for graph homomorphism games. The resulting relation is a quasi-order on finite graphs, and hence gives a partial order after…

Combinatorics · Mathematics 2026-05-20 Yangjing Long

The notions of bounded-size and quasibounded-size decompositions with bounded treedepth base classes are central to the structural theory of graph sparsity introduced by two of the authors years ago, and provide a characterization of both…

Discrete Mathematics · Computer Science 2024-12-24 Samuel Braunfeld , Jaroslav Nešetřil , Patrice Ossona de Mendez , Sebastian Siebertz

Lettericity is a graph parameter responsible for many attractive structural properties. In particular, graphs of bounded lettericity have bounded linear clique-width and they are well-quasi-ordered by induced subgraphs. The latter property…

Combinatorics · Mathematics 2024-02-21 Bogdan Alecu , Mamadou Moustapha Kanté , Vadim Lozin , Viktor Zamaraev

Quasi-isometry is a measure of how similar two graphs are at `large-scale'. Nguyen, Scott, and Seymour [arXiv:2501.09839] and Hickingbotham [arXiv:2501.10840] independently gave a characterisation of graphs quasi-isometric to graphs of…

Combinatorics · Mathematics 2025-12-29 Marc Distel

In a quest to thoroughly understand the first-order transduction hierarchy of hereditary graph classes, some questions in particular stand out; such as, what properties hold for graph classes that are first-order transductions of planar…

Logic in Computer Science · Computer Science 2025-06-12 Petr Hliněný , Jan Jedelský

We prove that hypergraphs defined by low-degree polynomial inequalities contain large homogeneous subsets. Formally, let $H$ be an $r$-uniform hypergraph on $N$ vertices that is semialgebraic of constant description complexity, and each…

Combinatorics · Mathematics 2026-02-23 Azem Adibelli , István Tomon

We consider the problem of classifying those graphs that arise as an undirected square of an oriented graph by generalising the notion of quasi-transitive directed graphs to mixed graphs. We fully classify those graphs of maximum degree…

Combinatorics · Mathematics 2023-11-09 Christopher Duffy

We introduce the graph theoretical parameter of edge treewidth. This parameter occurs in a natural way as the tree-like analogue of cutwidth or, alternatively, as an edge-analogue of treewidth. We study the combinatorial properties of…

Discrete Mathematics · Computer Science 2021-12-15 Loïc Magne , Christophe Paul , Abhijat Sharma , Dimitrios M. Thilikos

Brauer and Thrall conjectured that a finite-dimensional algebra over a field of bounded representation type is actually of finite representation type and a finite-dimensional algebra (over an infinite field) of infinite representation type…

Representation Theory · Mathematics 2018-05-25 Fahimeh Sadat Fotouhi , Alex Martsinkovsky , Shokrollah Salarian

Let $X$ be an ordered vector space. The net $\{x_\alpha\}\subseteq X$ is semi unbounded order convergent to $x$ (in symbol $x_\alpha\xrightarrow{suo}x$), if there is a net $\{y_\beta\}$, possibly over a different index set, such that…

Functional Analysis · Mathematics 2022-01-03 Masoumeh Ebrahimzadeh , Kazem Haghnejad Azar

We give a combinatorial characterization of the group of quasiconformal homeomorphisms of a closed, oriented surface $S$ of genus at least $2$. In particular, we prove they are exactly the automorphisms of a graph of essential quasicircles…

Geometric Topology · Mathematics 2026-01-16 Katherine Williams Booth , Alexander Nolte , Yvon Verberne