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We prove that every graph which admits a tree-decomposition into finite parts has a rooted tree-decomposition into finite parts that is linked, tight and componental. As an application, we obtain that every graph without half-grid minor has…

Combinatorics · Mathematics 2024-05-14 Sandra Albrechtsen , Raphael W. Jacobs , Paul Knappe , Max Pitz

Consider a host hypergraph $G$ which contains a spanning structure due to minimum degree considerations. We collect three results proving that if the edges of $G$ are sampled at the appropriate rate then the spanning structure still appears…

Combinatorics · Mathematics 2023-05-17 Huy Tuan Pham , Ashwin Sah , Mehtaab Sawhney , Michael Simkin

Tree-decompositions and treewidth are of fundamental importance in structural and algorithmic graph theory. The "spread" of a tree-decomposition is the minimum integer $s$ such that every vertex lies in at most $s$ bags. A…

Combinatorics · Mathematics 2026-04-08 Marc Distel , Neel Kaul , Raj Kaul , David R. Wood

We prove that several natural graph classes have tree-decompositions with minimum width such that each bag has bounded treewidth. For example, every planar graph has a tree-decomposition with minimum width such that each bag has treewidth…

Combinatorics · Mathematics 2025-12-01 Kevin Hendrey , David R. Wood

We make progress on three long standing conjectures from the 1960s about path and cycle decompositions of graphs. Gallai conjectured that any connected graph on $n$ vertices can be decomposed into at most $\left\lceil…

Combinatorics · Mathematics 2022-02-09 António Girão , Bertille Granet , Daniela Kühn , Deryk Osthus

A graph $G$ is said to be $p$-locally dense if every induced subgraph of $G$ with linearly many vertices has edge density at least $p$. A famous conjecture of Kohayakawa, Nagle, R\"odl, and Schacht predicts that locally dense graphs have,…

Combinatorics · Mathematics 2024-06-19 Domagoj Bradač , Benny Sudakov , Yuval Wigderson

Let $G$ be a connected graph in which almost all vertices have linear degrees and let $T$ be a uniform spanning tree of $G$. For any fixed rooted tree $F$ of height $r$ we compute the asymptotic density of vertices $v$ for which the…

Probability · Mathematics 2018-11-26 Jan Hladký , Asaf Nachmias , Tuan Tran

There are many results asserting the existence of tree-decompositions of minimal width which still represent local connectivity properties of the underlying graph, perhaps the best-known being Thomas' theorem that proves for every graph $G$…

Combinatorics · Mathematics 2017-03-13 Joshua Erde

An old conjecture of Erd{\H{o}}s and Gallai states that every $n$ vertex graph can be decomposed, that is $E(G)$ can be partitioned, into $O(n)$ cycles and edges. The covering version of this conjecture was proven by Pyber in 1985, where it…

Combinatorics · Mathematics 2025-09-09 Saieed Akbari , Jonny Aloni , Arash Beikmohammadi , Alexander Clow

We prove that every $n$-vertex $K_t$-minor-free graph $G$ of maximum degree $\Delta$ has a set $F$ of $O(t^2(\log t)^{1/4}\sqrt{\Delta n})$ edges such that every component of $G - F$ has at most $n/2$ vertices. This is best possible up to…

Combinatorics · Mathematics 2023-10-24 Gwenaël Joret , William Lochet , Michał T. Seweryn

We show that if a planar graph $G$ with minimum degree at least $3$ has positive Lin-Lu-Yau Ricci curvature on every edge, then $\Delta(G)\leq 17$, which then implies that $G$ is finite. This is an analogue of a result of DeVos and Mohar…

Combinatorics · Mathematics 2020-10-09 Linyuan Lu , Zhiyu Wang

A theorem of Frieze from 1985 asserts that the total weight of the minimum spanning tree of the complete graph $K_n$ whose edges get independent weights from the distribution $UNIFORM[0,1]$ converges to Ap\'ery's constant in probability, as…

Combinatorics · Mathematics 2025-04-14 Jan Hladký , Gopal Viswanathan

There are many intriguing questions in extremal graph theory that are well-understood in the undirected setting and yet remain elusive for digraphs. A natural instance of such a problem was recently studied by Hons, Klimo\v{s}ov\'{a},…

Combinatorics · Mathematics 2025-05-28 Micha Christoph , Raphael Steiner

In this paper, we make progress on a question related to one of Galvin that has attracted substantial attention recently. The question is that of determining among all graphs $G$ with $n$ vertices and $\Delta(G)\leq r$, which has the most…

Combinatorics · Mathematics 2014-05-07 Jonathan Cutler , A. J. Radcliffe

This is the second of a series of four papers in which we prove the following relaxation of the Loebl-Komlos--Sos Conjecture: For every $\alpha>0$ there exists a number $k_0$ such that for every $k>k_0$ every $n$-vertex graph $G$ with at…

Combinatorics · Mathematics 2017-07-31 Jan Hladký , János Komlós , Diana Piguet , Miklós Simonovits , Maya J. Stein , Endre Szemerédi

A well-known conjecture of Erd\H{o}s and S\'os states that every graph with average degree exceeding $m-1$ contains every tree with $m$ edges as a subgraph. We propose a variant of this conjecture, which states that every graph of maximum…

Combinatorics · Mathematics 2020-12-14 Frédéric Havet , Bruce Reed , Maya Stein , David R. Wood

Over 50 years ago, Erd\H{o}s and Gallai conjectured that the edges of every graph on $n$ vertices can be decomposed into $O(n)$ cycles and edges. Among other results, Conlon, Fox and Sudakov recently proved that this holds for the random…

Combinatorics · Mathematics 2019-02-20 Dániel Korándi , Michael Krivelevich , Benny Sudakov

In 1990 Erd\H{o}s, Faudree, Rousseau and Schelp proved that for $k\geq 2$, every graph with $n\geq k+1$ vertices and $(k-1)(n-k+2)+\binom{k-2}{2}+1$ edges contains a subgraph of minimum degree $k$ on at most $n-\sqrt{n}/\sqrt{6k^3}$…

Combinatorics · Mathematics 2017-03-02 Frank Mousset , Andreas Noever , Nemanja Škorić

Let $\mathcal{G}_{\alpha}$ be a hereditary graph class (i.e, every subgraph of $G_{\alpha}\in \mathcal{G}_{\alpha}$ belongs to $\mathcal{G}_{\alpha}$) such that every graph $G_{\alpha}$ in $\mathcal{G}_{\alpha}$ has minimum degree at most…

Combinatorics · Mathematics 2018-09-11 Xin Zhang , Bei Niu

Tree-decompositions of graphs are of fundamental importance in structural and algorithmic graph theory. The main property of tree-decompositions is the width (the maximum size of a bag minus 1). We show that every graph has a…

Combinatorics · Mathematics 2026-05-08 David R. Wood
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