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We introduce a notion for hierarchical graph clustering which we call the expander hierarchy and show a fully dynamic algorithm for maintaining such a hierarchy on a graph with $n$ vertices undergoing edge insertions and deletions using…

Data Structures and Algorithms · Computer Science 2020-07-22 Gramoz Goranci , Harald Räcke , Thatchaphol Saranurak , Zihan Tan

A \emph{tree-partition} of a graph $G$ is a proper partition of its vertex set into `bags', such that identifying the vertices in each bag produces a forest. The \emph{tree-partition-width} of $G$ is the minimum number of vertices in a bag…

Combinatorics · Mathematics 2009-04-02 David R. Wood

We present a dynamic data structure representing a graph G, which allows addition and removal of edges from G and can determine the number of appearances of a graph of a bounded size as an induced subgraph of G. The queries are answered in…

Data Structures and Algorithms · Computer Science 2013-01-04 Zdenek Dvorak , Vojtech Tuma

Many hard algorithmic problems dealing with graphs, circuits, formulas and constraints admit polynomial-time upper bounds if the underlying graph has small treewidth. The same problems often encourage reducing the maximal degree of vertices…

Discrete Mathematics · Computer Science 2011-11-04 Igor Markov , Yaoyun Shi

Diestel and M\"uller showed that the connected tree-width of a graph $G$, i.e., the minimum width of any tree-decomposition with connected parts, can be bounded in terms of the tree-width of $G$ and the largest length of a geodesic cycle in…

Combinatorics · Mathematics 2017-02-15 Matthias Hamann , Daniel Weißauer

Let G = (V, E) be a directed and weighted graph with vertex set V of size n and edge set E of size m, such that each edge (u, v) \in E has a real-valued weight w(u, c). An arborescence in G is a subgraph T = (V, E') such that for a vertex u…

Data Structures and Algorithms · Computer Science 2023-11-07 Joaquim Espada , Alexandre P. Francisco , Tatiana Rocher , Luís M. S. Russo , Cátia Vaz

A maximal independent set (MIS) can be maintained in an evolving $m$-edge graph by simply recomputing it from scratch in $O(m)$ time after each update. But can it be maintained in time sublinear in $m$ in fully dynamic graphs? We answer…

Data Structures and Algorithms · Computer Science 2018-02-28 Sepehr Assadi , Krzysztof Onak , Baruch Schieber , Shay Solomon

In this paper, we consider maintaining strongly connected components (SCCs) of a directed planar graph subject to edge insertions and deletions. We show a data structure maintaining an implicit representation of the SCCs within…

Data Structures and Algorithms · Computer Science 2024-06-18 Adam Karczmarz , Marcin Smulewicz

In a variety of applications, we need to keep track of the development of a data set over time. For maintaining and querying this multi version data I/O-efficiently, external memory data structures are required. In this paper, we present a…

General Literature · Computer Science 2007-05-23 Saju Jude Dominic , G. Sajith

The following theorem is proved: For all $k$-connected graphs $G$ and $H$ each with at least $n$ vertices, the treewidth of the cartesian product of $G$ and $H$ is at least $k(n -2k+2)-1$. For $n\gg k$ this lower bound is asymptotically…

Combinatorics · Mathematics 2013-10-02 David R. Wood

In Chordal/Interval Vertex Deletion we ask how many vertices one needs to remove from a graph to make it chordal (respectively: interval). We study these problems under the parameterization by treewidth $tw$ of the input graph $G$. On the…

Data Structures and Algorithms · Computer Science 2025-01-31 Michal Wlodarczyk

We give new deterministic bounds for fully-dynamic graph connectivity. Our data structure supports updates (edge insertions/deletions) in $O(\log^2n/\log\log n)$ amortized time and connectivity queries in $O(\log n/\log\log n)$ worst-case…

Data Structures and Algorithms · Computer Science 2012-09-26 Christian Wulff-Nilsen

We present a framework for dynamically maintaining $k$-edge-connectivity of an undirected simple graph $G$ under edge insertions and deletions, where $k$ is a fixed constant. After an edge insertion, the algorithm identifies and removes a…

Data Structures and Algorithms · Computer Science 2026-03-10 Blazej Wrobel

We give improved algorithms for maintaining edge-orientations of a fully-dynamic graph, such that the out-degree of each vertex is bounded. On one hand, we show how to orient the edges such that the out-degree of each vertex is proportional…

Data Structures and Algorithms · Computer Science 2023-11-07 Chandra Chekuri , Aleksander Bjørn Christiansen , Jacob Holm , Ivor van der Hoog , Kent Quanrud , Eva Rotenberg , Chris Schwiegelshohn

The treewidth of a graph is an important invariant in structural and algorithmic graph theory. This paper studies the treewidth of line graphs. We show that determining the treewidth of the line graph of a graph $G$ is equivalent to…

Combinatorics · Mathematics 2014-09-25 Daniel J. Harvey , David R. Wood

Answering connectivity queries is fundamental to fully dynamic graphs where edges and vertices are inserted and deleted frequently. Existing work proposes data structures and algorithms with worst-case guarantees. We propose a new data…

Data Structures and Algorithms · Computer Science 2022-07-19 Qing Chen , Oded Lachish , Sven Helmer , Michael Böhlen

A geometric graph associated with a set of points $P= \{x_1, x_2, \cdots, x_n \} \subset \mathbb{R}^d$ and a fixed kernel function $\mathsf{K}:\mathbb{R}^d\times \mathbb{R}^d\to\mathbb{R}_{\geq 0}$ is a complete graph on $P$ such that the…

Data Structures and Algorithms · Computer Science 2026-03-05 Yang Cao , Yichuan Deng , Wenyu Jin , Xiaoyu Li , Zhao Song , Xiaorui Sun , Omri Weinstein

Given a simple $n$-vertex, $m$-edge graph $G$ undergoing edge insertions and deletions, we give two new fully dynamic algorithms for exactly maintaining the edge connectivity of $G$ in $\tilde{O}(n)$ worst-case update time and…

Data Structures and Algorithms · Computer Science 2024-03-25 Gramoz Goranci , Monika Henzinger , Danupon Nanongkai , Thatchaphol Saranurak , Mikkel Thorup , Christian Wulff-Nilsen

Motivated by recent applications of dominator computations, we consider the problem of dynamically maintaining the dominators of flow graphs through a sequence of insertions and deletions of edges. Our main theoretical contribution is a…

Data Structures and Algorithms · Computer Science 2016-04-12 Loukas Georgiadis , Giuseppe F. Italiano , Luigi Laura , Federico Santaroni

Fully dynamic graph is a data structure that (1) supports edge insertions and deletions and (2) answers problem specific queries. The time complexity of (1) and (2) are referred to as the update time and the query time respectively. There…

Data Structures and Algorithms · Computer Science 2014-04-30 Yoichi Iwata , Keigo Oka