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In this paper, we revisit the split decomposition of graphs and give new combinatorial and algorithmic results for the class of totally decomposable graphs, also known as the distance hereditary graphs, and for two non-trivial subclasses,…

Discrete Mathematics · Computer Science 2011-04-19 Emeric Gioan , Christophe Paul

The sequence A120986 in the Encyclopedia of Integer Sequences counts ternary trees according to the number of nodes and the number of middle edges. Using a certain substition, the underlying cubic equation can be factored. This leads to an…

Combinatorics · Mathematics 2020-09-16 Helmut Prodinger

In light of the grammar given by Ji for the $(\alpha,\beta)$-Eulerian polynomials introduced by Carlitz and Scoville, we provide a labeling scheme for increasing binary trees. In this setting, we obtain a combinatorial interpretation of the…

Combinatorics · Mathematics 2025-03-31 William Y. C. Chen , Amy M. Fu

We show that the partition function of the logarithmic sector of critical topologically massive gravity which represents a series expansion of composition of functions, can be expressed as a sum over rooted trees. Our work brings a…

High Energy Physics - Theory · Physics 2024-03-29 Yannick Mvondo-She

We present a bijective algorithm with which an arbitrary permutation decomposes canonically into elementary blocks which we call families, which are sets with a specified number of ascents and descents. We show that families, arranged in an…

Combinatorics · Mathematics 2013-04-05 Adrian Ocneanu

In this paper, we give a simple combinatorial explanation of a formula of A. Postnikov relating bicolored rooted trees to bicolored binary trees. We also present generalized formulas for the number of labeled k-ary trees, rooted labeled…

Combinatorics · Mathematics 2007-05-23 Seunghyun Seo

We recall the occupancy problem introduced by Konheim & Weiss in 1966 and we consider parking functions as hash maps. Each car $c_i$ prefers parking space $p_i$ (the hash map $c_i \mapsto p_i$ with $c_i$ is a key and $p_i$ an index into an…

Combinatorics · Mathematics 2015-03-17 Jean-Baptiste Priez

We introduce a family of polynomials, which arise in three distinct ways: in the large $N$ expansion of a matrix integral, as a weighted enumeration of factorisations of permutations, and via the topological recursion. More explicitly, we…

Combinatorics · Mathematics 2025-07-02 Xavier Coulter , Norman Do , Ellena Moskovsky

In this paper, we survey some properties, encoding, and bijections involving combinatorial maps, double occurrence words, and chord diagrams. We particularly study quasi-trees from a purely combinatorial point of view and derive a…

Combinatorics · Mathematics 2022-11-16 Robert Cori , Yiting Jiang , Patrice Ossona de Mendez , Pierre Rosenstiehl

We study tree-to-tree transformations that can be defined in first-order logic or monadic second-order logic. We prove a decomposition theorem, which shows that every transformation can be obtained from prime transformations, such as…

Formal Languages and Automata Theory · Computer Science 2023-01-31 Mikołaj Bojańczyk , Amina Doumane

We introduce an efficient way, called Newton algorithm, to study arbitrary ideals in C[[x,y]], using a finite succession of Newton polygons. We codify most of the data of the algorithm in a useful combinatorial object, the Newton tree. For…

Algebraic Geometry · Mathematics 2014-02-26 Pierrette Cassou-Noguès , Willem Veys

We give a short and direct proof of a remarkable identity that arises in the enumeration of labeled trees with respect to their indegree sequence, where all edges are oriented from the vertex with lower label towards the vertex with higher…

Combinatorics · Mathematics 2016-01-20 Stephan Wagner

This note presents an encoding and a decoding algorithms for a forest of (labelled) rooted uniform hypertrees and hypercycles in linear time, by using as few as $n - 2$ integers in the range $[1,n]$. It is a simple extension of the…

Discrete Mathematics · Computer Science 2011-10-04 Christian Lavault

We show that the class of finite rooted binary plane trees is a Ramsey class (with respect to topological embeddings that map leaves to leaves). That is, for all such trees P,H and every natural number k there exists a tree T such that for…

Combinatorics · Mathematics 2010-05-26 Manuel Bodirsky , Diana Piguet

We develop a notion of a dual of a graph, generalizing the definition of Goulden and Yong (which only applied to trees), and reproving their main result using our new notion. We in fact give three definitions of the dual: a graph-theoretic…

Combinatorics · Mathematics 2017-04-12 Nikolaos Apostolakis , Kerry Ojakian

Phylogenetic networks are leaf-labelled directed acyclic graphs that are used to describe non-treelike evolutionary histories and are thus a generalization of phylogenetic trees. The hybridization number of a phylogenetic network is the sum…

Data Structures and Algorithms · Computer Science 2016-06-01 Leo van Iersel , Steven Kelk , Nela Lekić , Chris Whidden , Norbert Zeh

In this brief note a straightforward combinatorial proof for an identity directly connecting rooted forests and unordered set partitions is provided. Furthermore, references that put this type of identity in the context of forest volumes…

Combinatorics · Mathematics 2019-07-11 Benjamin Hackl

We prove identifiability of the tree parameters of the 3-class Jukes-Cantor mixture model. The proof uses ideas from algebraic statistics, in particular: finding phylogenetic invariants that separate the varieties associated to different…

Populations and Evolution · Quantitative Biology 2014-08-12 Colby Long , Seth Sullivant

This paper considers the enumeration of ternary trees (i.e. rooted ordered trees in which each vertex has 0 or 3 children) avoiding a contiguous ternary tree pattern. We begin by finding recurrence relations for several simple tree…

Combinatorics · Mathematics 2011-12-30 Nathan Gabriel , Katherine Peske , Lara Pudwell , Samuel Tay

Three-way dissimilarities are a generalization of (two-way) dissimilarities which can be used to indicate the lack of homogeneity or resemblance between any three objects. Such maps have applications in cluster analysis, and have been used…

Combinatorics · Mathematics 2017-10-19 Katharina T. Huber , Vincent Moulton , Guillaume E. Scholz