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A theta is a graph formed by three paths between the same pair of distinct vertices so that the union of any two of the paths induces a hole. A wheel is a graph formed by a hole and a node that has at least 3 neighbors in the hole. In this…

Combinatorics · Mathematics 2023-10-23 Marko Radovanović , Nicolas Trotignon , Kristina Vušković

We compute a minimum degree threshold sufficient for 3-partite graphs to admit a fractional triangle decomposition. Together with recent work of Barber, K\"uhn, Lo, Osthus and Taylor, this leads to bounds for exact decompositions and in…

Combinatorics · Mathematics 2016-09-13 Flora C. Bowditch , Peter J. Dukes

The cycles are the only $2$-connected graphs in which any two nonadjacent vertices form a vertex cut. We generalize this fact by proving that for every integer $k\ge 3$ there exists a unique graph $G$ satisfying the following conditions:…

Combinatorics · Mathematics 2022-10-28 Yanan Hu , Xingzhi Zhan , Leilei Zhang

We study graphs on $n$ vertices which have $2n-2$ edges and no proper induced subgraphs of minimum degree $3$. Erd\H{o}s, Faudree, Gy\'arf\'as, and Schelp conjectured that such graphs always have cycles of lengths $3,4,5,\dots, C(n)$ for…

Combinatorics · Mathematics 2014-08-25 Lothar Narins , Alexey Pokrovskiy , Tibor Szabó

Understanding how the cycles of a graph or digraph behave in general has always been an important point of graph theory. In this paper, we study the question of finding a set of $k$ vertex-disjoint cycles (resp. directed cycles) of distinct…

Combinatorics · Mathematics 2016-01-11 Julien Bensmail , Ararat Harutyunyan , Ngoc Khang Le , Binlong Li , Nicolas Lichiardopol

We generalise a fundamental graph-theoretical fact, stating that every element of the cycle space of a graph is a sum of edge-disjoint cycles, to arbitrary continua. To achieve this we replace graph cycles by topological circles, and…

General Topology · Mathematics 2011-10-28 Agelos Georgakopoulos

Motivated by an old question of Gallai (1966) on the intersection of longest paths in a graph and the well-known conjectures of Lov\'{a}sz (1969) and Thomassen (1978) on the maximum length of paths and cycles in vertex-transitive graphs, we…

Combinatorics · Mathematics 2025-08-05 Sergey Norin , Raphael Steiner , Stephan Thomassé , Paul Wollan

Let $G$ be a graph of order $n$. The path decomposition of $G$ is a set of disjoint paths, say $\mathcal{P}$, which cover all vertices of $G$. If all paths are induced paths in $G$, then we say $\mathcal{P}$ is an induced path decomposition…

Combinatorics · Mathematics 2019-12-03 S. Akbari , H. R. Maimani , A. Seify

A cycle of length $t$ in a hypergraph is an alternating sequence $v_1,e_1,v_2\dots,v_t,e_t$ of distinct vertices $v_i$ and distinct edges $e_i$ so that $\{v_i,v_{i+1}\}\subseteq e_i$ (with $v_{t+1}:=v_1$). Let $\lambda K_n^h$ be the…

Combinatorics · Mathematics 2018-09-26 Amin Bahmanian , Sadegheh Haghshenas

A separating system of a graph $G$ is a family $\mathcal{S}$ of subgraphs of $G$ for which the following holds: for all distinct edges $e$ and $f$ of $G$, there exists an element in $\mathcal{S}$ that contains $e$ but not $f$. Recently, it…

Combinatorics · Mathematics 2024-07-03 Fábio Botler , Tássio Naia

We study properties of random subcomplexes of partitions returned by (a suitable form of) the Strong Hypergraph Regularity Lemma, which we call regular slices. We argue that these subcomplexes capture many important structural properties of…

Combinatorics · Mathematics 2014-11-19 Peter Allen , Julia Böttcher , Oliver Cooley , Richard Mycroft

We consider questions related to the existence of spanning trees in graphs with the property that after the removal of any path in the tree the graph remains connected. We show that, for planar graphs, the existence of trees with this…

Combinatorics · Mathematics 2019-04-29 Cristina G. Fernandes , César Hernández-Vélez , Orlando Lee , José C. de Pina

A graph is strongly even-cycle decomposable if the edge set of every subdivision with an even number of edges can be partitioned into cycles of even length. We prove that several fundamental composition operations that preserve the property…

Combinatorics · Mathematics 2016-12-28 Tony Huynh , Andrew D. King , Sang-il Oum , Maryam Verdian-Rizi

We present results on partitioning the vertices of $2$-edge-colored graphs into monochromatic paths and cycles. We prove asymptotically the two-color case of a conjecture of S\'ark\"ozy: the vertex set of every $2$-edge-colored graph can be…

Combinatorics · Mathematics 2015-09-21 Jozsef Balogh , Janos Barat , Daniel Gerbner , Andras Gyarfas , GAbor N. Sarkozy

We study a large family of graph covering problems, whose definitions rely on distances, for graphs of bounded cyclomatic number (that is, the minimum number of edges that need to be removed from the graph to destroy all cycles). These…

Discrete Mathematics · Computer Science 2025-09-03 Dibyayan Chakraborty , Florent Foucaud , Anni Hakanen

We introduce and study "path odd-covers", a weakening of Gallai's path decomposition problem and a strengthening of the linear arboricity problem. The "path odd-cover number" $p_2(G)$ of a graph $G$ is the minimum cardinality of a…

Combinatorics · Mathematics 2023-06-13 Steffen Borgwardt , Calum Buchanan , Eric Culver , Bryce Frederickson , Puck Rombach , Youngho Yoo

We present a new technique for efficiently removing almost all short cycles in a graph without unintentionally removing its triangles. Consequently, triangle finding problems do not become easy even in almost $k$-cycle free graphs, for any…

Data Structures and Algorithms · Computer Science 2022-10-18 Amir Abboud , Karl Bringmann , Seri Khoury , Or Zamir

The Shortest Cycle Cover Conjecture of Alon and Tarsi asserts that the edges of every bridgeless graph with $m$ edges can be covered by cycles of total length at most $7m/5=1.400m$. We show that every cubic bridgeless graph has a cycle…

Combinatorics · Mathematics 2017-07-11 Tomas Kaiser , Daniel Kral , Bernard Lidicky , Pavel Nejedly , Robert Samal

Balogh, Bar\'at, Gerbner, Gy\'arf\'as, and S\'ark\"ozy proposed the following conjecture. Let $G$ be a graph on $n$ vertices with minimum degree at least $3n/4$. Then for every $2$-edge-colouring of $G$, the vertex set $V(G)$ may be…

Combinatorics · Mathematics 2015-02-27 Shoham Letzter

We study graphs with the property that every edge-colouring admits a monochromatic cycle (the length of which may depend freely on the colouring) and describe those graphs that are minimal with this property. We show that every member in…

Combinatorics · Mathematics 2018-08-01 Damian Reding , Anusch Taraz
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