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In this paper we give fast distributed graph algorithms for detecting and listing small subgraphs, and for computing or approximating the girth. Our algorithms improve upon the state of the art by polynomial factors, and for girth, we…

Data Structures and Algorithms · Computer Science 2021-01-20 Keren Censor-Hillel , Orr Fischer , Tzlil Gonen , François Le Gall , Dean Leitersdorf , Rotem Oshman

The Path Contraction and Cycle Contraction problems take as input an undirected graph $G$ with $n$ vertices, $m$ edges and an integer $k$ and determine whether one can obtain a path or a cycle, respectively, by performing at most $k$ edge…

Data Structures and Algorithms · Computer Science 2024-03-12 R. Krithika , V. K. Kutty Malu , Prafullkumar Tale

We present an improved algorithm for computing the $4$-edge-connected components of an undirected graph in linear time. The new algorithm uses only elementary data structures, and it is simple to describe and to implement in the pointer…

Data Structures and Algorithms · Computer Science 2021-08-20 Loukas Georgiadis , Giuseppe F. Italiano , Evangelos Kosinas

In the subgraph counting problem, we are given a input graph $G(V, E)$ and a target graph $H$; the goal is to estimate the number of occurrences of $H$ in $G$. Our focus here is on designing sublinear-time algorithms for approximately…

Data Structures and Algorithms · Computer Science 2018-11-20 Sepehr Assadi , Michael Kapralov , Sanjeev Khanna

Let H be a connected bipartite graph with n nodes and m edges. We give an O(nm) time algorithm to decide whether H is an interval bigraph. The best known algorithm has time complexity O(nm^6(m + n) \log n) and it was developed in 1997 [18].…

Data Structures and Algorithms · Computer Science 2018-05-22 Arash Rafiey

A planar orthogonal drawing of a planar 4-graph G (i.e., a planar graph with vertex-degree at most four) is a crossing-free drawing that maps each vertex of G to a distinct point of the plane and each edge of $G$ to a sequence of horizontal…

Computational Geometry · Computer Science 2022-05-17 Walter Didimo , Michael Kaufmann , Giuseppe Liotta , Giacomo Ortali

We consider the problem of finding \textit{semi-matching} in bipartite graphs which is also extensively studied under various names in the scheduling literature. We give faster algorithms for both weighted and unweighted case. For the…

Data Structures and Algorithms · Computer Science 2012-06-15 Jittat Fakcharoenphol , Bundit Laekhanukit , Danupon Nanongkai

Understanding how a vertex relates to a set of vertices is a fundamental task in graph analysis. Given a graph $G$ and a vertex set $X \subseteq V(G)$, consider the collection of subsets of the form $N(u) \cap X$ where $u$ ranges over all…

Data Structures and Algorithms · Computer Science 2025-12-01 Christine Awofeso , Pål Grønås Drange , Patrick Greaves , Oded Lachish , Felix Reidl

The problem of subgraph counting asks for the number of occurrences of a pattern graph $H$ as a subgraph of a host graph $G$ and is known to be computationally challenging: it is $\#W[1]$-hard even when $H$ is restricted to simple…

Data Structures and Algorithms · Computer Science 2026-03-27 Christine Awofeso , Patrick Greaves , Oded Lachish , Felix Reidl

We describe a simple variant of Hierholzer's algorithm that finds an Eulerian cycle in a (multi)graph with $n$ vertices and $m$ edges using $\mathrm{O}(n \lg m)$ bits of working memory. This substantially improves the working space compared…

Data Structures and Algorithms · Computer Science 2025-10-29 Ziad Ismaili Alaoui , Detlef Plump , Sebastian Wild

In this paper, we consider the problem of finding a cycle of length $2k$ (a $C_{2k}$) in an undirected graph $G$ with $n$ nodes and $m$ edges for constant $k\ge2$. A classic result by Bondy and Simonovits [J.Comb.Th.'74] implies that if $m…

Data Structures and Algorithms · Computer Science 2017-03-31 Søren Dahlgaard , Mathias Bæk Tejs Knudsen , Morten Stöckel

We provide a fast distributed algorithm for detecting $h$-cycles in the \textsf{Congested Clique} model, whose running time decreases as the number of $h$-cycles in the graph increases. In undirected graphs, constant-round algorithms are…

Data Structures and Algorithms · Computer Science 2024-08-28 Keren Censor-Hillel , Tomer Even , Virginia Vassilevska Williams

Given an undirected graph $G$ and an error parameter $\epsilon > 0$, the {\em graph sparsification} problem requires sampling edges in $G$ and giving the sampled edges appropriate weights to obtain a sparse graph $G_{\epsilon}$ with the…

Data Structures and Algorithms · Computer Science 2010-05-06 Ramesh Hariharan , Debmalya Panigrahi

An independent set in a graph G is a set of pairwise non-adjacent vertices. A graph $G$ is bipartite if its vertex set can be partitioned into two independent sets. In the Odd Cycle Transversal problem, the input is a graph $G$ along with a…

Data Structures and Algorithms · Computer Science 2024-02-20 Akanksha Agrawal , Paloma T. Lima , Daniel Lokshtanov , Pawel Rzążewski , Saket Saurabh , Roohani Sharma

We consider the problem of incremental cycle detection and topological ordering in a directed graph $G = (V, E)$ with $|V| = n$ nodes. In this setting, initially the edge-set $E$ of the graph is empty. Subsequently, at each time-step an…

Data Structures and Algorithms · Computer Science 2018-10-09 Sayan Bhattacharya , Janardhan Kulkarni

Permutation $\sigma$ appears in permutation $\pi$ if there exists a subsequence of $\pi$ that is order-isomorphic to $\sigma$. The natural question is to check if $\sigma$ appears in $\pi$, and if so count the number of occurrences. We know…

Data Structures and Algorithms · Computer Science 2020-10-02 Bartłomiej Dudek , Paweł Gawrychowski

The quartet distance is a measure of similarity used to compare two unrooted phylogenetic trees on the same set of $n$ leaves, defined as the number of subsets of four leaves related by a different topology in both trees. After a series of…

Data Structures and Algorithms · Computer Science 2020-12-03 Bartłomiej Dudek , Paweł Gawrychowski

Counting small patterns in a large dataset is a fundamental algorithmic task. The most common version of this task is subgraph/homomorphism counting, wherein we count the number of occurrences of a small pattern graph $H$ in an input graph…

Data Structures and Algorithms · Computer Science 2025-10-21 Daniel Paul-Pena , C. Seshadhri

Identifying dense bipartite subgraphs is a common graph data mining task. Many applications focus on the enumeration of all maximal bicliques (MBs), though sometimes the stricter variant of maximal induced bicliques (MIBs) is of interest.…

Data Structures and Algorithms · Computer Science 2019-03-06 Blair D. Sullivan , Andrew van der Poel , Trey Woodlief

This work presents a study of star covers on graphs. Unlike traditional formulations that minimize the number of stars, our aim is to optimize the number of bipartite components used in the cover. This problem, motivated by a symmetric…

Combinatorics · Mathematics 2026-05-19 Damjana Kokol Bukovšek , Polona Oblak , Helena Šmigoc