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We investigate the joint distribution of the vertex degrees in three models of random bipartite graphs. Namely, we can choose each edge with a specified probability, choose a specified number of edges, or specify the vertex degrees in one…

Combinatorics · Mathematics 2022-12-22 Brendan D. McKay , Fiona Skerman

We study a general model of recursive trees where vertices are equipped with independent weights and at each time-step a vertex is sampled with probability proportional to its fitness function (a function of its weight and degree) and…

Probability · Mathematics 2022-04-26 Tejas Iyer

We investigate the relation between degree sequences of trees and the majorization order using the Muirhead theorem. In this way, we prove a theorem that provides a necessary and sufficient condition for delta sequences of trees to be…

Combinatorics · Mathematics 2024-07-22 Leo Egghe , Ronald Rousseau

In 1995, Koml\'os, S\'ark\"ozy and Szemer\'edi showed that every large $n$-vertex graph with minimum degree at least $(1/2 + \gamma)n$ contains all spanning trees of bounded degree. We consider a generalization of this result to loose…

Combinatorics · Mathematics 2024-05-03 Yanitsa Pehova , Kalina Petrova

In this paper, we provide algorithms to rank, unrank, and randomly generate certain degree-restricted classes of Cayley trees. Specifically, we consider classes of trees that have a given degree sequence or a given multiset of degrees. If…

Combinatorics · Mathematics 2010-09-13 Jeffery B. Remmel , S. Gill Williamson

Arthur Cayley famously proved that there are n to the power n-2 labeled trees on n vertices. Here we go much further and show how to enumerate, fully automatically, labeled trees such that every vertex has a number of neighbors that belongs…

Combinatorics · Mathematics 2022-02-22 Shalosh B. Ekhad , Doron Zeilberger

Hasunuma [J. Graph Theory 102 (2023) 423-435] conjectured that for any tree $T$ of order $m$, every $k$-connected (or $k$-edge-connected) graph $G$ with minimum degree at least $k+m-1$ contains a tree $T'\cong T$ such that $G-E(T')$ is…

Combinatorics · Mathematics 2023-03-08 Qing Yang , Yingzhi Tian

In this paper, we prove that every $n$-vertex connected $K_{1,5}$-free graph $G$ with $\sigma_4(G)\geq n-1$ contains a spanning tree with at most $5$ leaves and branch vertices in total. Moreover, the degree sum condition "$\sigma_4(G)\geq…

Combinatorics · Mathematics 2022-07-12 Pham Hoang Ha , Nguyen Hoang Trang

The \emph{spanning tree packing number} of a graph $G$ is the maximum number of edge-disjoint spanning trees contained in $G$. Let $k\geq 1$ be a fixed integer. Palmer and Spencer proved that in almost every random graph process, the…

Combinatorics · Mathematics 2013-01-08 Xiaolin Chen , Xueliang Li , Huishu Lian

It is known that graphs on n vertices with minimum degree at least 3 have spanning trees with at least n/4+2 leaves and that this can be improved to (n+4)/3 for cubic graphs without the diamond K_4-e as a subgraph. We generalize the second…

Combinatorics · Mathematics 2007-07-19 Paul Bonsma , Florian Zickfeld

In this paper, we show that every planar graph without $4$-cycles and $6$-cycles has a partition of its vertex set into two sets, where one set induces a forest, and the other induces a forest with maximum degree at most $2$ (equivalently,…

Combinatorics · Mathematics 2022-03-15 Pongpat Sittitrai , Kittikorn Nakprasit

The Graceful Tree Conjecture of Rosa from 1967 asserts that the vertices of each tree T of order n can be injectively labelled by using the numbers {1,2,...,n} in such a way that the absolute differences induced on the edges are pairwise…

Combinatorics · Mathematics 2020-06-23 Anna Adamaszek , Peter Allen , Codrut Grosu , Jan Hladky

Consider the following process on a simple graph without isolated vertices: Order the edges randomly and keep an edge if and only if it contains a vertex which is not contained in some preceding edge. The resulting set of edges forms a…

Combinatorics · Mathematics 2017-09-12 Zhanar Berikkyzy , Steve Butler , Jay Cummings , Kristin Heysse , Paul Horn , Ruth Luo , Brent Moran

We prove that for all $0\leq t\leq k$ and $d\geq 2k$, every graph $G$ with treewidth at most $k$ has a `large' induced subgraph $H$, where $H$ has treewidth at most $t$ and every vertex in $H$ has degree at most $d$ in $G$. The order of $H$…

Combinatorics · Mathematics 2007-05-23 Prosenjit Bose , Vida Dujmovic , David R. Wood

The Gy\'arf\'as tree packing conjecture states that any set of $n-1$ trees $T_{1},T_{2},..., T_{n-1}$ such that $T_i$ has $n-i+1$ vertices pack into $K_n$. We show that $t=1/10n^{1/4}$ trees $T_1,T_2,..., T_t$ such that $T_i$ has $n-i+1$…

Combinatorics · Mathematics 2012-12-18 József Balogh , Cory Palmer

The Barat-Thomassen conjecture, recently proved in [Bensmail et al.: A proof of the Barat-Thomassen conjecture. J. Combin. Theory Ser. B, 124:39-55, 2017.], asserts that for every tree T, there is a constant $c_T$ such that every $c_T$-edge…

Combinatorics · Mathematics 2018-03-13 Tereza Klimošová , Stéphan Thomassé

The degree sequence of a graph is a numerical method to characterize the properties of graphs. Generalized forms of degree sequences exist for complete graphs and complete graphs. Nikolopolus et al. characterized the number of spanning…

Combinatorics · Mathematics 2019-06-17 Joshua Steier

A branchwise-real tree is a partial order which is a tree and in which every branch is isomorphic to a real interval. I give constructions of such trees which are both rigid (i.e. without non-trivial order-automorphisms) and uniform (in two…

Logic · Mathematics 2023-03-10 Sam Adam-Day

The {\sc Directed Maximum Leaf Out-Branching} problem is to find an out-branching (i.e. a rooted oriented spanning tree) in a given digraph with the maximum number of leaves. In this paper, we obtain two combinatorial results on the number…

Data Structures and Algorithms · Computer Science 2008-03-06 N Alon , F. V. Fomin , G. Gutin , M. Krivelevich , S. Saurabh

The subtrees and BC-subtrees (subtrees where any two leaves are at even distance apart) have been extensively studied in recent years. Such structures, under special constraints on degrees, have applications in many fields. Through an…

Combinatorics · Mathematics 2021-10-08 Yu Yang , Xiao-xiao Li , Meng-yuan Jin , Long Li , Hua Wang , Xiao-Dong Zhang
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