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A branch vertex in a tree is a vertex of degree at least three. We prove that, for all $s\geq 1$, every connected graph on $n$ vertices with minimum degree at least $(\frac{1}{s+3}+o(1))n$ contains a spanning tree having at most $s$ branch…

Combinatorics · Mathematics 2019-10-10 Louis DeBiasio , Allan Lo

We prove that the Loop O(1) model, a well-known graphical expansion of the Ising model, is a factor of i.i.d. on unimodular random rooted graphs under various conditions, including in the presence of a non-negative external field. As an…

Probability · Mathematics 2021-12-07 Omer Angel , Gourab Ray , Yinon Spinka

A spanning tree of a graph is a connected subgraph on all vertices with the minimum number of edges. The number of spanning trees in a graph $G$ is given by Matrix Tree Theorem in terms of principal minors of Laplacian matrix of $G$. We…

Combinatorics · Mathematics 2018-05-15 Keivan Hassani Monfared , Sudipta Mallik

Given a spanning tree $T$ of a planar graph $G$, the co-tree of $T$ is the spanning tree of the dual graph $G^*$ with edge set $(E(G)-E(T))^*$. Gr\"unbaum conjectured in 1970 that every planar 3-connected graph $G$ contains a spanning tree…

Discrete Mathematics · Computer Science 2024-02-09 Christian Ortlieb , Jens M. Schmidt

The directions of an infinite graph $G$ are a tangle-like description of its ends: they are choice functions that choose compatibly for all finite vertex sets $X\subseteq V(G)$ a component of $G-X$. Although every direction is induced by a…

Combinatorics · Mathematics 2021-01-19 Jan Kurkofka , Ruben Melcher

We show that the total variation mixing time is not quasi-isometry invariant, even for Cayley graphs. Namely, we construct a sequence of pairs of Cayley graphs with maps between them that twist the metric in a bounded way, while the ratio…

Probability · Mathematics 2024-11-20 Jonathan Hermon , Gady Kozma

We consider a Gibbs distribution over all spanning trees of an undirected, edge weighted finite graph, where, up to normalization, the probability of each tree is given by the product of its edge weights. Defining the weighted degree of a…

Discrete Mathematics · Computer Science 2024-10-18 Enrique Fita Sanmartín , Christoph Schnörr , Fred A. Hamprecht

We prove that any graph $G$ with $n$ points has a distribution $\mathcal{T}$ over spanning trees such that for any edge $(u,v)$ the expected stretch $E_{T \sim \mathcal{T}}[d_T(u,v)/d_G(u,v)]$ is bounded by $\tilde{O}(\log n)$. Our result…

Data Structures and Algorithms · Computer Science 2008-08-15 Ittai Abraham , Yair Bartal , Ofer Neiman

We prove that every (possibly infinite) graph of degree at most $d$ has a 4-dependent random proper $4^{d(d+1)/2}$-coloring, and one can construct it as a finitary factor of iid. For unimodular transitive (or unimodular random) graphs we…

Probability · Mathematics 2024-02-28 Ádám Timár

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

Let $G$ be a connected graph and $L(G)$ the set of all integers $k$ such that $G$ contains a spanning tree with exactly $k$ leaves. We show that for a connected graph $G$, the set $L(G)$ is contiguous. It follows from work of Chen, Ren, and…

Combinatorics · Mathematics 2024-11-20 Kenta Noguchi , Carol T. Zamfirescu

In previous work, we defined the intersection graph of a chord diagram associated with a string link (as in the theory of finite type invariants). In this paper, we look at the case when this graph is a tree, and we show that in many cases…

Geometric Topology · Mathematics 2009-01-10 Blake Mellor

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

In this paper, we first prove that if the edges of $K_{2m}$ are properly colored by $2m-1$ colors in such a way that any two colors induce a 2-factor of which each component is a 4-cycle, then $K_{2m}$ can be decomposed into $m$ isomorphic…

Combinatorics · Mathematics 2016-05-17 Hung-Lin Fu , Yuan-Hsun Lo

We give an asymptotic expression for the expected number of spanning trees in a random graph with a given degree sequence $\boldsymbol{d}=(d_1,\ldots, d_n)$, provided that the number of edges is at least $n + \textstyle{\frac{1}{2}}…

Combinatorics · Mathematics 2017-02-21 Catherine Greenhill , Mikhail Isaev , Matthew Kwan , Brendan D. McKay

In this note, we give a nature action of the modular group on the ends of the infinite (p + 1)-cayley tree, for each prime p. We show that there is a unique invariant probability measure for each p.

Dynamical Systems · Mathematics 2017-06-08 Shilei Fan , Yanqi Qiu

We consider a class of reinforcement processes, called WARMs, on tree graphs. These processes involve a parameter $\alpha$ which governs the strength of the reinforcement, and a collection of Poisson processes indexed by the vertices of the…

Probability · Mathematics 2020-09-17 Christian Hirsch , Mark Holmes , Victor Kleptsyn

The celebrated formula of Otter \emph{[Ann. of Math. (2) 49 (1948), 583--599]} asserts that the complete graph contains exponentially many non-isomorphic spanning trees. In this paper, we show that every connected almost regular graph with…

Combinatorics · Mathematics 2026-01-13 Hyunwoo Lee

The incidence matrix of a graph is totally unimodular if and only if the graph is bipartite, i.e., it contains no odd cycles. We extend the characterization of total unimodularity to hypergraphs whose hyperedges of size at least four are…

Combinatorics · Mathematics 2025-08-26 Marco Caoduro , Meike Neuwohner , Joseph Paat

We study "positive" graphs that have a nonnegative homomorphism number into every edge-weighted graph (where the edgeweights may be negative). We conjecture that all positive graphs can be obtained by taking two copies of an arbitrary…

Combinatorics · Mathematics 2014-01-31 Omar Antolín Camarena , Endre Csóka , Tamás Hubai , Gábor Lippner , László Lovász