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We classify weighted forests up to the blowing-up and blowing-down operations which are relevant for the study of algebraic surfaces.

Algebraic Geometry · Mathematics 2007-05-23 Daniel Daigle

We consider packing tree degree sequences in this paper. We set up a conjecture that any arbitrary number of tree degree sequences without common leaves have edge disjoint tree realizations. This conjecture is known to be true for $2$ and…

Combinatorics · Mathematics 2017-04-12 Aravind Gollakota , William Hardt , Istvan Miklos

We investigate the tractability of a simple fusion of two fundamental structures on graphs, a spanning tree and a perfect matching. Specifically, we consider the following problem: given an edge-weighted graph, find a minimum-weight…

Data Structures and Algorithms · Computer Science 2024-07-12 Kristóf Bérczi , Tamás Király , Yusuke Kobayashi , Yutaro Yamaguchi , Yu Yokoi

A weighted recursive tree is an evolving tree in which vertices are assigned random vertex-weights and new vertices connect to a predecessor with a probability proportional to its weight. Here, we study the maximum degree and near-maximum…

Probability · Mathematics 2023-01-31 Laura Eslava , Bas Lodewijks , Marcel Ortgiese

Weighted Szeged index is a recently introduced extension of the well-known Szeged index. In this paper, we present a new tool to analyze and characterize minimum weighted Szeged index trees. We exhibit the best trees with up to 81 vertices…

Combinatorics · Mathematics 2020-07-22 Pavol Hell , César Hernández-Cruz , Seyyed Aliasghar Hosseini

In this thesis the properties of two kinds of non-uniform random recursive trees are studied. In the first model weights are assigned to each node, thus altering the attachment probabilities. We will call these trees weighted recursive…

Probability · Mathematics 2017-10-05 Ella Hiesmayr

In this note we discuss trees similar to the Calkin-Wilf tree, a binary tree that enumerates all positive rational numbers in a simple way. The original construction of Calkin and Wilf is reformulated in a more algebraic language, and an…

Number Theory · Mathematics 2012-01-10 Robert A. Kucharczyk

A model of irrigation network, where lower branches must be thicker in order to support the weight of the higher ones, was recently introduced in BSUN2 [4]. This leads to a countable family of ODEs, describing the thickness of every branch,…

Optimization and Control · Mathematics 2021-04-29 Qing Sun

A graph is called integral if all eigenvalues of its adjacency matrix consist entirely of integers. We prove that for a given nullity more than 1, there are only finitely many integral trees. It is also shown that integral trees with…

Combinatorics · Mathematics 2015-04-24 E. Ghorbani , A. Mohammadian , B. Tayfeh-Rezaie

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

This is a survey article on trees, with a modest number of proofs to give a flavor of the way these topologies can be efficiently handled. Trees are defined in set-theorist fashion as partially ordered sets in which the elements below each…

General Topology · Mathematics 2007-05-23 Peter J. Nyikos

We introduce weighted regular tree grammars with storage as combination of (a) regular tree grammars with storage and (b) weighted tree automata over multioperator monoids. Each weighted regular tree grammar with storage generates a…

Formal Languages and Automata Theory · Computer Science 2023-06-22 Zoltán Fülöp , Luisa Herrmann , Heiko Vogler

We study random bipartite planar maps defined by assigning nonnegative weights to each face of a map. We prove that for certain choices of weights a unique large face, having degree proportional to the total number of edges in the maps,…

Probability · Mathematics 2015-06-05 Svante Janson , Sigurdur Örn Stefánsson

Binary trees are fundamental objects in models of evolutionary biology and population genetics. Here, we discuss some of their combinatorial and structural properties as they depend on the tree class considered. Furthermore, the process by…

Populations and Evolution · Quantitative Biology 2021-06-30 Thomas Wiehe

A weighted digraph is balanced if the sums of the weights of the incoming and of the outgoing edges are equal at each vertex. We show that if these sums are integers, then the edge weights can be integers as well.

Optimization and Control · Mathematics 2020-11-20 Mohamed-Ali Belabbas , Xudong Chen

We consider finite trees with edges labeled by letters on a finite alphabet $\varSigma$. Each pair of nodes defines a unique labeled path whose trace is a word of the free monoid $\varSigma^*$. The set of all such words defines the language…

Combinatorics · Mathematics 2015-05-12 Srečko Brlek , Nadia Lafrenière , Xavier Provençal

We study the conditions under which the isometry of spaces with metrics generated by weights given on the edges of finite trees is equivalent to the isomorphism of these trees. Similar questions are studied for ultrametric spaces generated…

Metric Geometry · Mathematics 2020-02-18 Oleksiy Dovgoshey

We describe symbolic constructions for listing and enumerating graphs having the same induced edge label sequence. We settle in the affirmative R. Whitty's [W08] conjectured existence of determinantal constructions for listing and…

Combinatorics · Mathematics 2020-05-01 Edinah K. Gnang , Isaac Wass

We define a new balance index for rooted phylogenetic trees based on the symmetry of the evolutive history of every set of 4 leaves. This index makes sense for multifurcating trees and it can be computed in time linear in the number of…

Populations and Evolution · Quantitative Biology 2019-03-25 Tomás M. Coronado , Arnau Mir , Francesc Rosselló , Gabriel Valiente

We study compact straight-line embeddings of trees. We show that perfect binary trees can be embedded optimally: a tree with $n$ nodes can be drawn on a $\sqrt n$ by $\sqrt n$ grid. We also show that testing whether a given binary tree has…

Computational Geometry · Computer Science 2018-09-03 Hugo A. Akitaya , Maarten Löffler , Irene Parada