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In this paper we find the generating function for the number of vertices which have $k$ elements in their subtree and use this generating function to calculate the probability that a vertex has a size $k$ subtree. We also show how this same…

Combinatorics · Mathematics 2019-04-12 Anthony Van Duzer

We provide formulas for generating functions of many types of paths in various rooted tree structures. We compute the $k$th moment of the generating functions for various types of vertical paths. In two specific familes of trees we find…

Combinatorics · Mathematics 2018-10-03 Keith Copenhaver

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

We describe a generating tree approach to the enumeration and exhaustive generation of k-nonnesting set partitions and permutations. Unlike previous work in the literature using the connections of these objects to Young tableaux and…

Combinatorics · Mathematics 2014-02-11 Sophie Burrill , Sergi Elizalde , Marni Mishna , Lily Yen

We consider a probability distribution on the set of Boolean functions in n variables which is induced by random Boolean expressions. Such an expression is a random rooted plane tree where the internal vertices are labelled with connectives…

Combinatorics · Mathematics 2015-09-28 Antoine Genitrini , Bernhard Gittenberger , Veronika Kraus , Cécile Mailler

Over some types of trees with a given number of vertices, which trees minimize or maximize the total number of subtrees or leaf containing subtrees are studied. Here are some of the main results:\ (1)\, Sharp upper bound on the total number…

Combinatorics · Mathematics 2012-06-15 Shuchao Li , Shujing Wang

We study that over some types of trees with a given number of vertices, which trees minimize or maximize the total number of subtrees. Trees minimizing (resp. maximizing) the total number of subtrees usually maximize (resp. minimize) the…

Combinatorics · Mathematics 2012-04-30 Shuchao Li , Shujing Wang

Given a graph, we can form a spanning forest by first sorting the edges in some order, and then only keep edges incident to a vertex which is not incident to any previous edge. The resulting forest is dependent on the ordering of the edges,…

Combinatorics · Mathematics 2018-02-16 Steve Butler , Misa Hamanaka , Marie Hardt

This paper investigates some properties of the number of subtrees of a tree with given degree sequence. These results are used to characterize trees with the given degree sequence that have the largest number of subtrees, which generalizes…

Combinatorics · Mathematics 2012-09-04 Xiu-Mei Zhang , Xiao-Dong Zhang , Daniel Gray , Hua Wang

Let $T$ be a weighted tree. The weight of a subtree $T_1$ of $T$ is defined as the product of weights of vertices and edges of $T_1$. We obtain a linear-time algorithm to count the sum of weights of subtrees of $T$. As applications, we…

Combinatorics · Mathematics 2007-05-23 Weigen Yan , Yeong-Nan Yeh

We give a simple formula for the number of hypertrees with $k$ hyperedges of given sizes and $n+1$ labelled vertices with prescribed degrees. A slight generalization of this formula counts labelled bipartite trees with prescribed degrees in…

Combinatorics · Mathematics 2011-02-15 Roland Bacher

We find generating functions the number of strings (words) containing a specified number of occurrences of certain types of order-isomorphic classes of substrings called subword patterns. In particular, we find generating functions for the…

Combinatorics · Mathematics 2007-05-23 A. Burstein , T. Mansour

A $k$-universal permutation, or $k$-superpermutation, is a permutation that contains all permutations of length $k$ as patterns. The problem of finding the minimum length of a $k$-superpermutation has recently received significant attention…

Combinatorics · Mathematics 2020-05-19 Colin Defant , Noah Kravitz , Ashwin Sah

We explore a generating function trick which allows us to keep track of infinitely many statistics using finitely many variables, by recording their individual distributions rather than their joint distributions. Building on previous work…

Combinatorics · Mathematics 2024-05-01 Sergi Elizalde

In this paper, we provide a polynomial time algorithm to calculate the probability of a {\it ranked} gene tree topology for a given species tree, where a ranked tree topology is a tree topology with the internal vertices being ordered. The…

Populations and Evolution · Quantitative Biology 2012-03-02 Tanja Stadler , James H. Degnan

Data structures known as $k$-d trees have numerous applications in scientific computing, particularly in areas of modern statistics and data science such as range search in decision trees, clustering, nearest neighbors search, local…

Data Structures and Algorithms · Computer Science 2022-01-21 Aritra Chakravorty , William S. Cleveland , Patrick J. Wolfe

A fringe subtree of a rooted tree is a subtree induced by one of the vertices and all its descendants. We consider the problem of estimating the number of distinct fringe subtrees in two types of random trees: simply generated trees and…

Combinatorics · Mathematics 2021-05-11 Louisa Seelbach Benkner , Stephan Wagner

We consider exact enumerations and probabilistic properties of ranked trees when generated under the random coalescent process. Using a new approach, based on generating functions, we derive several statistics such as the exact probability…

Combinatorics · Mathematics 2012-08-21 Filippo Disanto , Thomas Wiehe

Using generating functions techniques we develop a relation between the Hausdorff and spectral dimension of trees with a unique infinite spine. Furthermore, it is shown that if the outgrowths along the spine are independent and identically…

Statistical Mechanics · Physics 2012-06-22 Sigurdur Orn Stefansson , Stefan Zohren

In this paper, we introduce two families of planar and self-similar graphs which have small-world properties. The constructed models are based on an iterative process where each step of a certain formulation of modules results in a final…

Combinatorics · Mathematics 2024-04-19 Muhammed Alaa Morsy , Mohamed Anwar , Abdallah Aboutahoun
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