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We study the fundamental question of how likely it is that two randomly chosen trees are isomorphic to each other for different models of random trees. We show that the probability decays exponentially for rooted labeled trees as well as…

Probability · Mathematics 2023-04-11 Christoffer Olsson

The AHU-algorithm solves the computationally difficult graph isomorphism problem for rooted trees, and does so with a linear time complexity. Although the AHU-algorithm has remained state of the art for almost 50 years, it has been…

Computational Complexity · Computer Science 2024-01-17 Anna Lindeberg

Explaining why and how a tree $t$ structurally differs from another tree $t^\star$ is a question that is encountered throughout computer science, including in understanding tree-structured data such as XML or JSON data. In this article, we…

Machine Learning · Computer Science 2025-02-19 Daniel Neider , Leif Sabellek , Johannes Schmidt , Fabian Vehlken , Thomas Zeume

We construct a pair of non-isomorphic, bipartite graphs which are not distinguished by counting the number of homomorphisms to any tree. This answers a question motivated by Atserias et al. (LICS 2021). In order to establish the…

Discrete Mathematics · Computer Science 2025-11-19 Anuj Dawar

Leader election is a basic symmetry breaking problem in distributed computing. All nodes of a network have to agree on a single node, called the leader. If the nodes of the network have distinct labels, then agreeing on a single node means…

Distributed, Parallel, and Cluster Computing · Computer Science 2017-02-20 Barun Gorain , Andrzej Pelc

We consider the well-studied pattern counting problem: given a permutation $\pi \in \mathbb{S}_n$ and an integer $k > 1$, count the number of order-isomorphic occurrences of every pattern $\tau \in \mathbb{S}_k$ in $\pi$. Our first result…

Data Structures and Algorithms · Computer Science 2024-07-09 Gal Beniamini , Nir Lavee

Large tree structures are ubiquitous and real-world relational datasets often have information associated with nodes (e.g., labels or other attributes) and edges (e.g., weights or distances) that need to be communicated to the viewers. Yet,…

Computational Geometry · Computer Science 2023-05-18 Kathryn Gray , Mingwei Li , Reyan Ahmed , Md. Khaledur Rahman , Ariful Azad , Stephen Kobourov , Katy Börner

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

We discuss a notion of convergence for binary trees that is based on subtree sizes. In analogy to recent developments in the theory of graphs, posets and permutations we investigate some general aspects of the topology, such as a…

Combinatorics · Mathematics 2024-02-14 Rudolf Grübel

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

In this paper we consider two aspects of the inverse problem of how to construct merge trees realizing a given barcode. Much of our investigation exploits a recently discovered connection between the symmetric group and barcodes in general…

Algebraic Topology · Mathematics 2021-07-27 Justin Curry , Jordan DeSha , Adélie Garin , Kathryn Hess , Lida Kanari , Brendan Mallery

Pr\"{u}fer codes provide an encoding scheme for representing a vertex-labeled tree on $n$ vertices with a string of length $n-2$. Indeed, two labeled trees are isomorphic if and only if their Pr\"{u}fer codes are identical, and this…

Combinatorics · Mathematics 2025-06-23 R. W. R. Darling , Grant Fickes

Reverse search is a convenient method for enumerating structured objects, that can be used both to address theoretical issues and to solve data mining problems. This method has already been successfully developed to handle unordered trees.…

Discrete Mathematics · Computer Science 2022-05-13 Florian Ingels , Romain Azaïs

Borrowing inspiration from Marcone and Mont\'{a}lban's one-one correspondence between the class of signed trees and the equimorphism classes of indecomposable scattered linear orders, we find a subclass of signed trees which has an…

Combinatorics · Mathematics 2022-02-10 Shashwat Agrawal , Amit Kuber , Esha Gupta

The early development of a zygote can be mathematically described by a developmental tree. To compare developmental trees of different species, we need to define distances on trees. If children cells after a division are not…

Combinatorics · Mathematics 2022-06-08 Yue Wang

We consider random binary trees that appear as the output of certain standard algorithms for sorting and searching if the input is random. We introduce the subtree size metric on search trees and show that the resulting metric spaces…

Probability · Mathematics 2014-05-06 Rudolf Grübel

We consider how to index strings, trees and graphs for jumbled pattern matching when we are asked to return a match if one exists. For example, we show how, given a tree containing two colours, we can build a quadratic-space index with…

Data Structures and Algorithms · Computer Science 2013-04-23 Ferdinando Cicalese , Travis Gagie , Emanuele Giaquinta , Eduardo Sany Laber , Zsuzsanna Lipták , Romeo Rizzi , Alexandru I. Tomescu

A characterization is provided for each natural number except one (1) by means of an ordered pair of elements. The first element is a natural number called the type of the natural number characterized, and the second is a natural number…

Artificial Intelligence · Computer Science 2020-02-24 Osvaldo Skliar , Sherry Gapper , Ricardo E. Monge

Many of the distributed localization algorithms are based on relaxed optimization formulations of the localization problem. These algorithms commonly rely on first-order optimization methods, and hence may require many iterations or…

Optimization and Control · Mathematics 2016-07-19 Sina Khoshfetrat Pakazad , Emre Özkan , Carsten Fritsche , Anders Hansson , Fredrik Gustafsson

This work addresses the intrinsic relationship between trees and networks (i.e. graphs). A complete (invertible) mapping is presented which allows trees to be mapped into weighted graphs and then backmapped into the original tree without…

Physics and Society · Physics 2008-08-07 Luciano da Fontoura Costa , Francisco Aparecido Rodrigues