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We prove that for any fixed r>=2, the tree-width of graphs not containing K_r as a topological minor (resp. as a subgraph) is bounded by a linear (resp. polynomial) function of their rank-width. We also present refinements of our bounds for…

Combinatorics · Mathematics 2014-03-26 Fedor V. Fomin , Sang-il Oum , Dimitrios M. Thilikos

Let $G$ be a connected graph with vertex set $V(G)$, and denote by $d_G(u,v)$ the distance from $u$ to $v$ in $G$, for any $u,v \in V(G)$. The average distance of an $n$-vertex connected graph $G$, denoted by $\mu(G)$, is defined to be the…

Combinatorics · Mathematics 2026-05-07 Zhibin Du , Xuli Qi

We prove that the spanning trees of any outerplanar triangulation $G$ can be listed so that any two consecutive spanning trees differ in an exchange of two edges that share an end vertex. For outerplanar graphs $G$ with faces of arbitrary…

Discrete Mathematics · Computer Science 2024-12-23 Nastaran Behrooznia , Torsten Mütze

In this paper, we present some new results describing connections between the spectrum of a regular graph and its generalized connectivity, toughness, and the existence of spanning trees with bounded degree.

Combinatorics · Mathematics 2016-02-19 Sebastian M. Cioabă , Xiaofeng Gu

We show that the diameter of a uniformly drawn spanning tree of a simple connected graph on $n$ vertices with minimal degree linear in $n$ is typically of order $\sqrt{n}$. A byproduct of our proof, which is of independent interest, is that…

Probability · Mathematics 2021-08-12 Noga Alon , Asaf Nachmias , Matan Shalev

A 2-tree is a graph that can be formed by starting with a triangle and iterating the operation of making a new vertex adjacent to two adjacent vertices of the existing graph. Leizhen Cai asked in 1995 whether every maximal planar graph…

Combinatorics · Mathematics 2022-03-22 Allan Bickle

For a spanning tree T of a connected graph G and for a labelling \phi: E(T) \rightarrow {+, -}, \phi is called an alternating sign on a spanning tree T of a graph G if for any cotree edge e \in E(G)-E(T), the unique path in T joining both…

Combinatorics · Mathematics 2013-02-18 Dongseok Kim , Young Soo Kwon , Jaeun Lee

We prove that a minor-closed class of graphs has bounded layered pathwidth if and only if some apex-forest is not in the class. This generalises a theorem of Robertson and Seymour, which says that a minor-closed class of graphs has bounded…

Combinatorics · Mathematics 2020-08-03 Vida Dujmović , David Eppstein , Gwenaël Joret , Pat Morin , David R. Wood

Rigidity, arising in discrete geometry, is the property of a structure that does not flex. Laman provides a combinatorial characterization of rigid graphs in the Euclidean plane, and thus rigid graphs in the Euclidean plane have…

Combinatorics · Mathematics 2018-06-14 Xiaofeng Gu

Motivated by a result of [17], we determine necessary and sufficient conditions on $F\/$ with $|E(F)| \leq n-1\/$ for which $K_n - F\/$ admits a $g$-angulation. For $|E(F)| \geq n\/$, we investigate the possibility of placing $F\/$ in…

Combinatorics · Mathematics 2019-06-14 Niran Abbas Ali , Gek L. Chiab , Hazim Michman Traoc , Adem Kilicman

Mader conjectured that for any tree $T$ of order $m$, every $k$-connected graph $G$ with minimum degree at least $\lfloor\frac{3k}{2}\rfloor +m-1$ contains a subtree $T'\cong T$ such that $G-V(T')$ is $k$-connected. In this paper, we give a…

Combinatorics · Mathematics 2021-01-29 Yanmei Hong , Qinghai Liu

A graph $G$ is $H$-free if any subset of $V(G)$ does not induce a subgraph of $G$ that is isomorphic to $H$. Given a graph $H$, we present sufficient and necessary conditions for a graph $G$ such that $G/e$ is $H$-free for any edge $e$ in…

Combinatorics · Mathematics 2022-12-20 Hany Ibrahim , Peter Tittmann

We say that a graph G has a perfect H-packing (also called an H-factor) if there exists a set of disjoint copies of H in G which together cover all the vertices of G. Given a graph H, we determine, asymptotically, the Ore-type degree…

Combinatorics · Mathematics 2009-06-02 Daniela Kühn , Deryk Osthus , Andrew Treglown

We consider the following question: How many edge-disjoint plane spanning trees are contained in a complete geometric graph $GK_n$ on any set $S$ of $n$ points in general position in the plane? We show that this number is in…

Computational Geometry · Computer Science 2017-07-19 Oswin Aichholzer , Thomas Hackl , Matias Korman , Marc van Kreveld , Maarten Löffler , Alexander Pilz , Bettina Speckmann , Emo Welzl

Let $G$ be a connected $n$-vertex graph in a proper minor-closed class $\mathcal G$. We prove that the extension complexity of the spanning tree polytope of $G$ is $O(n^{3/2})$. This improves on the $O(n^2)$ bounds following from the work…

Combinatorics · Mathematics 2021-12-21 Manuel Aprile , Samuel Fiorini , Tony Huynh , Gwenaël Joret , David R. Wood

The minimum stretch spaning tree problem for a grah G is to find a spaning tree T of G such as that the maximum distance in T between two adjacent vertices is minimized. The minimum value of this optimization problem gives rise to a grpah…

Combinatorics · Mathematics 2018-07-24 Lan Lin , Yixun Lin

Let $\tau(G)$ denote the spanning tree packing number of a graph $G$. Recently, Zhang and Fan [J. Graph Theory 112 (2) (2026) 128--144] posed the problem of finding a tight spectral radius condition for an $m$-edge-connected graph $G$ to…

Combinatorics · Mathematics 2026-05-14 Yongbin Gao , Ligong Wang

We prove that every amenable one-ended Cayley graph has an invariant spanning tree of one end. More generally, for any 1-ended amenable unimodular random graph we construct a factor of iid percolation (jointly unimodular subgraph) that is…

Probability · Mathematics 2020-05-11 Adam Timar

Let $k\ge 2$ be an integer and $T_1,\ldots, T_k$ be spanning trees of a graph $G$. If for any pair of vertices $(u,v)$ of $V(G)$, the paths from $u$ to $v$ in each $T_i$, $1\le i\le k$, do not contain common edges and common vertices,…

Discrete Mathematics · Computer Science 2014-09-23 Benoit Darties , Nicolas Gastineau , Olivier Togni

Let $\mathbb{G}^{D}$ be the set of graphs $G(V,\, E)$ with $\left|V\right|=n$, and the degree sequence equal to $D=(d_{1},\, d_{2},\,\dots,\, d_{n})$. In addition, for $\frac{1}{2}<a<1$, we define the set of graphs with an almost given…

Probability · Mathematics 2014-02-24 Behzad Mehrdad
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