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In 2020, we initiated a systematic study of graph classes in which the treewidth can only be large due to the presence of a large clique, which we call $(\mathrm{tw},\omega)$-bounded. While $(\mathrm{tw},\omega)$-bounded graph classes are…

Combinatorics · Mathematics 2023-10-18 Clément Dallard , Martin Milanič , Kenny Štorgel

The Erd\H{o}s-Gy\'{a}rf\'{a}s conjecture states that every graph with minimum degree at least three has a cycle whose length is a power of 2. Since this conjecture has proven to be far from reach, Hobbs asked if the…

In 1968, Erd\"os and Lov\'asz conjectured that for every graph $G$ and all integers $s,t\geq 2$ such that $s+t-1=\chi(G) > \omega(G)$, there exists a partition $(S,T)$ of the vertex set of $G$ such that $\chi(G|S)\geq s$ and $\chi(G|T)\geq…

Combinatorics · Mathematics 2013-09-05 Maria Chudnovsky , Alexandra Fradkin , Matthieu Plumettaz

Treewidth is an important graph invariant, relevant for both structural and algorithmic reasons. A necessary condition for a graph class to have bounded treewidth is the absence of large cliques. We study graph classes closed under taking…

Combinatorics · Mathematics 2021-11-09 Clément Dallard , Martin Milanič , Kenny Štorgel

The complete bipartite graph $K_{1,3}$ is called a claw. The properties of claw-free graphs have attracted considerable attention, with research on claw-free planar graphs tracing back to Plummer's work in 1989. In this paper, we extend…

Combinatorics · Mathematics 2025-10-28 Licheng Zhang , Zhangdong Ouyang , Yuanqiu Huang

We show that for every positive integer ${t \geq 2}$ there exists an integer $s$ such that every graph that contains no induced subgraph isomorphic to either the $6$-vertex path or the $(2,t)$-biclique, the complete bipartite graph…

Combinatorics · Mathematics 2026-04-03 Maria Chudnovsky , Julien Codsi , J. Pascal Gollin , Martin Milanič , Varun Sivashankar

This introduction to graphs and graph algebras provides the optimal bound for the number of all paths of length $k$ in a graph with $N\geq k$ edges and no loops. Our proof relies on a construction of a number of terminating algorithms that…

Rings and Algebras · Mathematics 2019-12-12 Piotr M. Hajac , Mariusz Tobolski

We show that the dominating set problem parameterized by solution size is fixed-parameter tractable (FPT) in graphs that do not contain the claw (K(1,3)), the complete bipartite graph on four vertices where the two parts have one and three…

Data Structures and Algorithms · Computer Science 2015-03-17 Marek Cygan , Geevarghese Philip , Marcin Pilipczuk , Michał Pilipczuk , Jakub Onufry Wojtaszczyk

We introduce the concept of Most, and Least, Compact Spanning Trees - denoted respectively by $T^*(G)$ and $T^\#(G)$ - of a simple, connected, undirected and unweighted graph $G(V, E, W)$. For a spanning tree $T(G) \in \mathcal{T}(G)$ to be…

Distributed, Parallel, and Cluster Computing · Computer Science 2022-06-22 Gyan Ranjan , Nishant Saurabh , Amit Ashutosh

For a non-decreasing positive integer sequence $S = (s_{1}, \dots, s_{k})$, an $S$-packing edge-coloring of a graph $G$ is a partition of the edge set of $G$ into subsets $E_{1}, \dots, E_{k}$ such that for each $1 \leq i \leq k$, the…

Combinatorics · Mathematics 2025-09-16 Jingxi Hou , Tao Wang , Xiaojing Yang

A graph $G$ belongs to the class ${\rm ORTH}[h,s,t]$ for integers $h$, $s$, and $t$ if there is a pair $(T,{\cal S})$, where $T$ is a tree of maximum degree at most $h$, and ${\cal S}$ is a collection $(S_u)_{u\in V(G)}$ of subtrees $S_u$…

Lifelong SLAM considers long-term operation of a robot where already mapped locations are revisited many times in changing environments. As a result, traditional graph-based SLAM approaches eventually become extremely slow due to the…

Robotics · Computer Science 2021-10-05 Gerhard Kurz , Matthias Holoch , Peter Biber

The Matching Cut problem is to decide if the vertex set of a connected graph can be partitioned into two non-empty sets $B$ and $R$ such that the edges between $B$ and $R$ form a matching, that is, every vertex in $B$ has at most one…

Combinatorics · Mathematics 2025-05-26 Jungho Ahn , Tala Eagling-Vose , Felicia Lucke , Daniël Paulusma , Siani Smith

A theta is a graph consisting of two non-adjacent vertices and three internally disjoint paths between them, each of length at least two. For a family $\mathcal{H}$ of graphs, we say a graph $G$ is $\mathcal{H}$-free if no induced subgraph…

Combinatorics · Mathematics 2022-09-09 Tara Abrishami , Maria Chudnovsky , Sepehr Hajebi , Sophie Spirkl

We consider problems of finding a maximum size/weight $t$-matching without forbidden subgraphs in an undirected graph $G$ with the maximum degree bounded by $t+1$, where $t$ is an integer greater than $2$. Depending on the variant forbidden…

Data Structures and Algorithms · Computer Science 2024-05-02 Katarzyna Paluch , Mateusz Wasylkiewicz

A graph is called claw-free if it contains no induced subgraph isomorphic to the complete bipartite graph $K_{1, 3}$. The undirected power graph of a group $G$ has vertices the elements of $G$, with an edge between $g_1$ and $g_2$ if one of…

Group Theory · Mathematics 2024-07-30 Pallabi Manna , Santanu Mandal , Andrea Lucchini

Many recent works address the question of characterizing induced obstructions to bounded treewidth. In 2022, Lozin and Razgon completely answered this question for graph classes defined by finitely many forbidden induced subgraphs. Their…

A graph $ G $ is minimally $ t $-tough if the toughness of $ G $ is $ t $ and deletion of any edge from $ G $ decreases its toughness. Katona et al. conjectured that the minimum degree of any minimally $ t $-tough graph is $ \lceil 2t\rceil…

Combinatorics · Mathematics 2022-07-27 Xiaomin Hu , Hui Ma , Weihua Yang

In this paper, we show that for any positive integer $m$ and $k\in [2]$, let $G$ be a $(2m+2k+2)$-connected graph and let $a_1,\ldots , a_m, s, t$ be any distinct vertices of $G$, there are $k$ internally disjoint $s$-$t$ paths $P_1,…

Combinatorics · Mathematics 2024-02-21 Yuzhen Qi , Jin Yan

We prove that for every tree $T$ which is not an edge, for almost every graph $G$ which does not contain $T$ as an induced subgraph, $V(G)$ has a partition into $\alpha(T)-1$ parts certifying this fact. Each part induces a graph which is…

Combinatorics · Mathematics 2025-06-03 Bruce Reed , Yelena Yuditsky