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This thesis studies the graph alignment problem, the noisy version of the graph isomorphism problem, which aims to find a matching between the nodes of two graphs which preserves most of the edges. Focusing on the planted version where the…

Data Structures and Algorithms · Computer Science 2024-04-22 Luca Ganassali

We extend Babai's quasipolynomial-time graph isomorphism test (STOC 2016) and develop a quasipolynomial-time algorithm for the multiple-coset isomorphism problem. The algorithm for the multiple-coset isomorphism problem allows to exploit…

Data Structures and Algorithms · Computer Science 2020-04-21 Daniel Wiebking

We give a Python program that is capable to compute and print all the distinct trivalent 2-stratifold graphs up to $N$ white vertices with trivial fundamental group. Our algorithm uses the three basic operations to construct new graphs from…

General Topology · Mathematics 2020-11-30 Myriam Hernández-Ketchul , Jesús Rodríguez-Viorato

Deciding whether a collection of unrooted trees is compatible is a fundamental problem in phylogenetics. Two different graph-theoretic characterizations of tree compatibility have recently been proposed. In one of these, tree compatibility…

Discrete Mathematics · Computer Science 2012-10-16 Sudheer Vakati , David Fernández-Baca

The isomorphism problem is known to be efficiently solvable for interval graphs, while for the larger class of circular-arc graphs its complexity status stays open. We consider the intermediate class of intersection graphs for families of…

Computational Complexity · Computer Science 2017-04-20 Johannes Köbler , Sebastian Kuhnert , Oleg Verbitsky

Graph transformation is the rule-based modification of graphs, and is a discipline dating back to the 1970s. In general, to match the left-hand graph of a fixed rule within a host graph requires polynomial time, but to improve matching…

Logic in Computer Science · Computer Science 2021-01-05 Graham Campbell , Detlef Plump

We study the complexity of testing if two given matroids are isomorphic. The problem is easily seen to be in $\Sigma_2^p$. In the case of linear matroids, which are represented over polynomially growing fields, we note that the problem is…

Computational Complexity · Computer Science 2008-11-25 Raghavendra Rao B. V. , Jayalal M. N. Sarma

This paper presents a new graph isomorphism invariant, called $\mathfrak{w}$-labeling, that can be used to design a polynomial-time algorithm for solving the graph isomorphism problem for various graph classes. For example, all…

Data Structures and Algorithms · Computer Science 2023-01-24 Alpár Jüttner , Péter Madarasi

It is unknown whether two graphs can be tested for isomorphism in polynomial time. A classical approach to the Graph Isomorphism Problem is the d-dimensional Weisfeiler-Lehman algorithm. The d-dimensional WL-algorithm can distinguish many…

Combinatorics · Mathematics 2010-12-10 Harm Derksen

The three-in-a-tree problem is to determine if a simple undirected graph contains an induced subgraph which is a tree connecting three given vertices. Based on a beautiful characterization that is proved in more than twenty pages,…

Data Structures and Algorithms · Computer Science 2022-01-06 Kai-Yuan Lai , Hsueh-I Lu , Mikkel Thorup

The graph isomorphism is to determine whether two graphs are isomorphic. A closely related problem is automorphism detection, where an isomorphism between two graphs is a bijection between their vertex sets that preserves adjacency, and an…

Social and Information Networks · Computer Science 2019-11-18 Can Lu , Jeffrey Xu Yu , Zhiwei Zhang , Hong Cheng

Finding an optimal assignment between two sets of objects is a fundamental problem arising in many applications, including the matching of `bag-of-words' representations in natural language processing and computer vision. Solving the…

Machine Learning · Computer Science 2019-09-12 Nils M. Kriege , Pierre-Louis Giscard , Franka Bause , Richard C. Wilson

We introduce in this paper a runtime-efficient tree hashing algorithm for the identification of isomorphic subtrees, with two important applications in genetic programming for symbolic regression: fast, online calculation of population…

Machine Learning · Computer Science 2021-07-23 Bogdan Burlacu , Lukas Kammerer , Michael Affenzeller , Gabriel Kronberger

We consider the problem of finding the smallest graph that contains two input trees each with at most $n$ vertices preserving their distances. In other words, we look for an isometric-universal graph with the minimum number of vertices for…

Data Structures and Algorithms · Computer Science 2025-06-17 Edgar Baucher , François Dross , Cyril Gavoille

Position heaps are index structures of text strings used for the string matching problem. They are rooted trees whose edges and nodes are labeled and numbered, respectively. This paper is concerned with variants of the inverse problem of…

Data Structures and Algorithms · Computer Science 2022-12-13 Koshiro Kumagai , Diptarama Hendrian , Ryo Yoshinaka , Ayumi Shinohara

An $H$-graph is one representable as the intersection graph of connected subgraphs of a suitable subdivision of a fixed graph $H$, introduced by Bir\'{o}, Hujter and Tuza (1992). An $H$-graph is proper if the representing subgraphs of $H$…

Data Structures and Algorithms · Computer Science 2022-03-24 Deniz Ağaoğlu Çağırıcı , Petr Hliněný

Color refinement is a classical technique used to show that two given graphs G and H are non-isomorphic; it is very efficient, although it does not succeed on all graphs. We call a graph G amenable to color refinement if it succeeds in…

Computational Complexity · Computer Science 2015-05-05 V. Arvind , Johannes Köbler , Gaurav Rattan , Oleg Verbitsky

An L(2,1)-labeling of a graph $G$ is an assignment $f$ from the vertex set $V(G)$ to the set of nonnegative integers such that $|f(x)-f(y)|\ge 2$ if $x$ and $y$ are adjacent and $|f(x)-f(y)|\ge 1$ if $x$ and $y$ are at distance 2, for all…

Data Structures and Algorithms · Computer Science 2010-11-25 Toru Hasunuma , Toshimasa Ishii , Hirotaka Ono , Yushi Uno

We present a complete classification of the deterministic distributed time complexity for a family of graph problems: binary labeling problems in trees. These are locally checkable problems that can be encoded with an alphabet of size two…

Distributed, Parallel, and Cluster Computing · Computer Science 2020-02-19 Alkida Balliu , Sebastian Brandt , Yuval Efron , Juho Hirvonen , Yannic Maus , Dennis Olivetti , Jukka Suomela

In this paper, we present fixed-parameter tractability algorithms for both the undirected and directed versions of the Spanning Tree Isomorphism Problem, parameterized by the size $k$ of a redundant set. A redundant set is a collection of…

Data Structures and Algorithms · Computer Science 2025-08-08 Fangjian Shen , Yicheng Zheng , Wushao Wen , Hankz Hankui Zhuo