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We construct a new bijection between the set of $n\times k$ $0$-$1$ matrices with no three $1$'s forming a $\Gamma$ configuration and the set of $(n,k)$-Callan sequences, a simple structure counted by poly-Bernoulli numbers. We give two…

Combinatorics · Mathematics 2019-11-28 Beáta Bényi , Gábor V. Nagy

In this article, we present a method to construct $e$-power $b$-happy numbers of any height. Using this method, we construct a tree that encodes these happy numbers, their heights, and their ancestry--relation to other happy numbers. For…

Number Theory · Mathematics 2024-10-21 Eva G. Goedhart , Yusuf Gurtas , Pamela E. Harris

For a labeled tree on the vertex set $\set{1,2,\ldots,n}$, the local direction of each edge $(i\,j)$ is from $i$ to $j$ if $i<j$. For a rooted tree, there is also a natural global direction of edges towards the root. The number of edges…

Combinatorics · Mathematics 2022-03-22 Heesung Shin , Jiang Zeng

We study generating functions of ordinary and plane partitions coloured by the action of a finite subgroup of the corresponding special linear group. After reviewing known results for the case of ordinary partitions, we formulate a…

Algebraic Geometry · Mathematics 2020-11-04 Ben Davison , Jared Ongaro , Balazs Szendroi

We survey the theory and applications of mating-of-trees bijections for random planar maps and their continuum analog: the mating-of-trees theorem of Duplantier, Miller, and Sheffield (2014). The latter theorem gives an encoding of a…

Probability · Mathematics 2023-02-16 Ewain Gwynne , Nina Holden , Xin Sun

In this note we consider ternary trees naturally embedded in the plane in a deterministic way such that the root has position zero, or in other words label zero, and the children of a node with position $j$ have positions $j-1$, $j$, and…

Combinatorics · Mathematics 2009-03-09 Markus Kuba

Recently, Zheng and Wu defined the concept of odd spanning tree of a graph, meaning a spanning tree in which every vertex has odd degree. Similar to Cayley's formula, Feng, Chen and Wu counted the number of odd spanning trees in complete…

Combinatorics · Mathematics 2026-02-17 Jun Ge , Yamin Yu

A new tree model is introduced based on ordered trees, by distinguishing exactly one child of each node that \emph{has} children. The basic enumeration leads to a cubic equation of the generating function. The extraction of its coefficients…

Combinatorics · Mathematics 2026-02-27 Helmut Prodinger

We present a bijection between some quadrangular dissections of an hexagon and unrooted binary trees, with interesting consequences for enumeration, mesh compression and graph sampling. Our bijection yields an efficient uniform random…

Combinatorics · Mathematics 2008-10-21 Eric Fusy , Dominique Poulalhon , Gilles Schaeffer

We generalize the concept of ascending and descending runs from permutations to rooted labelled trees and mappings, i.e., functions from the set $\{1, \dots, n\}$ into itself. A combinatorial decomposition of the corresponding functional…

Combinatorics · Mathematics 2020-07-06 Marie-Louise Lackner , Alois Panholzer

Graceful tree conjecture is a well-known open problem in graph theory. Here we present a computational approach to this conjecture. An algorithm for finding graceful labelling for trees is proposed. With this algorithm, we show that every…

Discrete Mathematics · Computer Science 2010-08-20 Wenjie Fang

For each positive integer $n$, we construct a bijection between the odd partitions and the distinct partitions of $n$ which extends Bressoud's bijection between the odd-and-distinct partitions of $n$ and the splitting partitions of $n$. We…

Combinatorics · Mathematics 2018-03-30 John Murray

Dawid, Kjaerulff and Lauritzen (1994) provided a preliminary description of a hybrid between Monte-Carlo sampling methods and exact local computations in junction trees. Utilizing the strengths of both methods, such hybrid inference methods…

Artificial Intelligence · Computer Science 2013-08-12 Uffe Kjærulff

Recently, Ehrenborg and Van Willenburg defined a class of bipartite graphs that correspond naturally to Ferrers diagrams, and proved several results about them. We give bijective proofs for the (already known) expressions for the number of…

Combinatorics · Mathematics 2007-05-23 Jason Burns

In any dimension $D$, the Euclidean Einstein-Hilbert action, which describes gravity in the absence of matter, can be discretized over random discrete spaces obtained by gluing families of polytopes together in all possible ways. In the…

Mathematical Physics · Physics 2018-08-29 Luca Lionni

We obtain first order linear partial differential equations which are satisfied by exponential generating functions of two variables for the number of connected bipartite graphs with given Betti number. By solving these equations…

Combinatorics · Mathematics 2023-05-16 Taro Hasui , Tomoyuki Shirai , Satoshi Yabuoku

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

We consider a pruning of the inhomogeneous continuum random trees, as well as the cut trees that encode the genealogies of the fragmentations that come with the pruning. We propose a new approach to the reconstruction problem, which has…

Probability · Mathematics 2023-02-03 Nicolas Broutin , Hui He , Minmin Wang

We give closed form expressions for the numbers of multi-rooted plane trees with specified degrees of root vertices. This results in an infinite number of integer sequences some of which are known to have an alternative interpretation. We…

Combinatorics · Mathematics 2024-02-06 Anwar Al Ghabra , K. Gopala Krishna , Patrick Labelle , Vasilisa Shramchenko

We give a general construction of triangulations starting from a walk in the quarter plane with small steps, which is a discrete version of the mating of trees. We use a special instance of this construction to give a bijection between maps…

Combinatorics · Mathematics 2021-02-01 Philippe Biane