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A subtree of a tree is any induced subgraph that is again a tree (i.e., connected). The mean subtree order of a tree is the average number of vertices of its subtrees. This invariant was first analyzed in the 1980s by Jamison. An intriguing…

Combinatorics · Mathematics 2021-06-11 Stijn Cambie , Stephan Wagner , Hua Wang

Polycyclic aromatic hydrocarbons (PAHs) are recognized as the primary contributors to the aromatic infrared bands (AIBs) widely observed in space. However, analyzing these AIBs remains challenging because of the immense structural diversity…

Astrophysics of Galaxies · Physics 2026-02-16 Guoqing Tang , Jiang He , Zhao Wang , Dong Qiu

For an integer $k\geq 2$, a spanning tree of a graph without vertices of degree from $2$ to $k$ is called a {\it $[2,k]$-ST} of the graph. The concept of $[2,k]$-STs is a natural extension of a homeomorphically irreducible spanning tree (or…

Combinatorics · Mathematics 2025-06-05 Michitaka Furuya , Shoichi Tsuchiya

The global structure of the minimal spanning tree (MST) is expected to be universal for a large class of underlying random discrete structures. However, very little is known about the intrinsic geometry of MSTs of most standard models, and…

Probability · Mathematics 2021-06-01 Louigi Addario-Berry , Sanchayan Sen

We study probability distributions over free algebras of trees. Probability distributions can be seen as particular (formal power) tree series [Berstel et al 82, Esik et al 03], i.e. mappings from trees to a semiring K . A widely studied…

Machine Learning · Computer Science 2008-07-21 François Denis , Amaury Habrard , Rémi Gilleron , Marc Tommasi , Édouard Gilbert

In the length-constrained minimum spanning tree (MST) problem, we are given an $n$-node edge-weighted graph $G$ and a length constraint $h \geq 1$. Our goal is to find a spanning tree of $G$ whose diameter is at most $h$ with minimum…

Data Structures and Algorithms · Computer Science 2025-06-17 D Ellis Hershkowitz , Richard Z Huang

Our previous paper shows that the (vertex) spanning tree degree enumerator polynomial of a connected graph $G$ is a real stable polynomial (id est is non-zero if all variables have positive imaginary parts) if and only if $G$ is…

Combinatorics · Mathematics 2023-10-30 Danila Cherkashin , Pavel Prozorov

We show that certain topologically defined uniform spanning tree probabilities for graphs embedded in an annulus can be computed as linear combinations of Pfaffians of matrices involving the line-bundle Green's function, where the…

Probability · Mathematics 2016-06-08 Greta Panova , David B. Wilson

The avalanche polynomial on a graph captures the distribution of avalanches in the abelian sandpile model. Studied on trees, this polynomial could be defined by simply considering the size of the subtrees of the original tree. In this…

Combinatorics · Mathematics 2009-05-19 Robert Cori , Anne Micheli , Dominique Rossin

We study the computational limits of the following general hypothesis testing problem. Let H=H_n be an \emph{arbitrary} undirected graph on n vertices. We study the detection task between a ``null'' Erd\H{o}s-R\'{e}nyi random graph G(n,p)…

Statistics Theory · Mathematics 2024-03-27 Xifan Yu , Ilias Zadik , Peiyuan Zhang

A closed-form formula is derived for the number of occurrences of matches of a multiset of patterns among all ordered (plane-planted) trees with a given number of edges. A pattern looks like a tree, with internal nodes and leaves, but also…

Discrete Mathematics · Computer Science 2020-06-30 Nachum Dershowitz

We study the entropy of the distribution of the set R_n of vertices visited by a simple random walk on a graph with bounded degrees in its first n steps. It is shown that this quantity grows linearly in the expected size of R_n if the graph…

Probability · Mathematics 2010-07-13 David Windisch

Let $G_n$ be a graph obtained by the strong product of $P_2$ and $C_n$, where $n\geqslant3$. In this paper, explicit expressions for the Kirchhoff index, multiplicative degree-Kirchhoff index and number of spanning trees of $G_n$ are…

Combinatorics · Mathematics 2019-06-12 Yingui Pan , Jianping Li

We study the average number of distinct fringe subtrees in random trees generated by leaf-centric binary tree sources as introduced by Zhang, Yang and Kieffer. A leaf-centric binary tree source induces for every $n \geq 2$ a probability…

Discrete Mathematics · Computer Science 2025-04-30 Louisa Seelbach Benkner , Markus Lohrey , Stephan Wagner

This paper extends the study of fringe trees in random plane trees with a given degree statistic. While previous work established the asymptotic normality of the count of fringe trees isomorphic to a fixed tree, we investigate the case…

Probability · Mathematics 2026-04-08 Gabriel Berzunza Ojeda , Cecilia Holmgren , Svante Janson

Patterns on numerical semigroups are multivariate linear polynomials, and they are said to be admissible if there exists a numerical semigroup such that evaluated at any nonincreasing sequence of elements of the semigroup gives integers…

Number Theory · Mathematics 2012-11-06 Maria Bras-Amorós , Pedro A. García-Sánchez , Albert Vico-Oton

An independent set of size $k$ in a finite undirected graph $G$ is a set of $k$ vertices of the graph, no two of which are connected by an edge. Let $x_{k}(G)$ be the number of independent sets of size $k$ in the graph $G$ and let…

Probability · Mathematics 2020-06-09 Steven Heilman

We call a pair of vertex-disjoint, induced subtrees of a rooted trees twins if they have the same counts of vertices by out-degrees. The likely maximum size of twins in a uniformly random, rooted Cayley tree of size $n\to\infty$ is studied.…

Combinatorics · Mathematics 2024-06-06 Miklos Bona , Ovidiu Costin , Boris Pittel

In the binomial random graph $\mathcal{G}(n,p)$, when $p$ changes from $(1-\varepsilon)/n$ (subcritical case) to $1/n$ and then to $(1+\varepsilon)/n$ (supercritical case) for $\varepsilon>0$, with high probability the order of the largest…

Combinatorics · Mathematics 2018-10-19 Oliver Cooley , Wenjie Fang , Nicola Del Giudice , Mihyun Kang

For a fixed graph H with t vertices, an H-factor of a graph G with n vertices, where t divides n, is a collection of vertex disjoint (not necessarily induced) copies of H in G covering all vertices of G. We prove that for a fixed tree T on…

Combinatorics · Mathematics 2014-04-02 Deepak Bal , Alan Frieze , Michael Krivelevich , Po-Shen Loh