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A graph with n vertices is 1-planar if it can be drawn in the plane such that each edge is crossed at most once, and is optimal if it has the maximum of 4n-8 edges. We show that optimal 1-planar graphs can be recognized in linear time. Our…

Discrete Mathematics · Computer Science 2018-01-25 Franz J. Brandenburg

In this paper, we consider the problem of designing cut sparsifiers and sketches for directed graphs. To bypass known lower bounds, we allow the sparsifier/sketch to depend on the balance of the input graph, which smoothly interpolates…

Data Structures and Algorithms · Computer Science 2021-05-13 Ruoxu Cen , Yu Cheng , Debmalya Panigrahi , Kevin Sun

We present an alternative and simpler method for computing principal typings of flow networks. When limited to planar flow networks, the method can be made to run in fixed-parameter linear-time -- where the parameter not to be exceeded is…

Data Structures and Algorithms · Computer Science 2018-07-20 Assaf Kfoury

We study the influence of a graph parameter called modular-width on the time complexity for optimally solving well-known polynomial problems such as Maximum Matching, Triangle Counting, and Maximum $s$-$t$ Vertex-Capacitated Flow. The…

Data Structures and Algorithms · Computer Science 2018-04-27 Stefan Kratsch , Florian Nelles

We introduce a new approach to the maximum flow problem in undirected, capacitated graphs using $\alpha$-\emph{congestion-approximators}: easy-to-compute functions that approximate the congestion required to route single-commodity demands…

Data Structures and Algorithms · Computer Science 2013-04-09 Jonah Sherman

Recent years have seen extensive research on directed graph sparsification. In this work, we initiate the study of fast fully dynamic spectral and cut sparsification algorithms for directed graphs. We introduce a new notion of spectral…

Data Structures and Algorithms · Computer Science 2025-07-29 Yibin Zhao

Consider a directed or an undirected graph with integral edge weights from the set [-W, W], that does not contain negative weight cycles. In this paper, we introduce a general framework for solving problems on such graphs using matrix…

Data Structures and Algorithms · Computer Science 2012-08-20 Marek Cygan , Harold N. Gabow , Piotr Sankowski

Given a family $\mathcal{F}$ of graphs, a graph is \emph{$\mathcal{F}$-subgraph-free} if it has no subgraph isomorphic to a member of $\mathcal{F}$. We present a fixed-parameter linear-time algorithm that decides whether a planar graph can…

Discrete Mathematics · Computer Science 2025-10-20 Shinwoo An , Seonghyuk Im , Seokbeom Kim , Myounghwan Lee

There has been a surge of interest in spectral hypergraph sparsification, a natural generalization of spectral sparsification for graphs. In this paper, we present a simple fully dynamic algorithm for maintaining spectral hypergraph…

Data Structures and Algorithms · Computer Science 2026-01-12 Sebastian Forster , Gramoz Goranci , Ali Momeni

We present a general method of designing fast approximation algorithms for cut-based minimization problems in undirected graphs. In particular, we develop a technique that given any such problem that can be approximated quickly on trees,…

Data Structures and Algorithms · Computer Science 2010-11-09 Aleksander Madry

Diffusion is a fundamental graph procedure and has been a basic building block in a wide range of theoretical and empirical applications such as graph partitioning and semi-supervised learning on graphs. In this paper, we study…

Data Structures and Algorithms · Computer Science 2021-06-07 Li Chen , Richard Peng , Di Wang

We propose a simple and computationally efficient method for dense subgraph discovery, which is a classic problem both in theory and in practice. It is well known that dense subgraphs can have strong correlation with structures of interest…

Data Structures and Algorithms · Computer Science 2019-10-18 Digvijay Boob , Yu Gao , Richard Peng , Saurabh Sawlani , Charalampos E. Tsourakakis , Di Wang , Junxing Wang

We study the problem of computing a minimum $s$--$t$ cut in an unweighted, undirected graph via \emph{cut queries}. In this model, the input graph is accessed through an oracle that, given a subset of vertices $S \subseteq V$, returns the…

Data Structures and Algorithms · Computer Science 2025-10-22 Yonggang Jiang , Danupon Nanongkai , Pachara Sawettamalya

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

In this paper we provide new randomized algorithms with improved runtimes for solving linear programs with two-sided constraints. In the special case of the minimum cost flow problem on $n$-vertex $m$-edge graphs with integer…

Data Structures and Algorithms · Computer Science 2021-08-24 Jan van den Brand , Yin Tat Lee , Yang P. Liu , Thatchaphol Saranurak , Aaron Sidford , Zhao Song , Di Wang

We explore the use of local algorithms in the design of streaming algorithms for the Maximum Directed Cut problem. Specifically, building on the local algorithm of Buchbinder et al. (FOCS'12) and Censor-Hillel et al. (ALGOSENSORS'17), we…

Data Structures and Algorithms · Computer Science 2024-12-02 Raghuvansh R. Saxena , Noah G. Singer , Madhu Sudan , Santhoshini Velusamy

We consider a new semidefinite programming relaxation for directed edge expansion, which is obtained by adding triangle inequalities to the reweighted eigenvalue formulation. Applying the matrix multiplicative weight update method to this…

Data Structures and Algorithms · Computer Science 2023-06-16 Lap Chi Lau , Kam Chuen Tung , Robert Wang

In this paper, we revisit the classic approximate All-Pairs Shortest Paths (APSP) problem in undirected graphs. For unweighted graphs, we provide an algorithm for $2$-approximate APSP in $\tilde O(n^{2.5-r}+n^{\omega(r)})$ time, for any…

Data Structures and Algorithms · Computer Science 2023-10-31 Michal Dory , Sebastian Forster , Yael Kirkpatrick , Yasamin Nazari , Virginia Vassilevska Williams , Tijn de Vos

The area of sublinear algorithms have recently received a lot of attention. In this setting, one has to choose specific access model for the input, as the algorithm does not have time to pre-process or even to see the whole input. A…

Data Structures and Algorithms · Computer Science 2020-09-24 Jakub Tětek

In this paper we introduce a notion of planarity for graphs that are presented in a streaming fashion. A $\textit{streamed graph}$ is a stream of edges $e_1,e_2,...,e_m$ on a vertex set $V$. A streamed graph is $\omega$-$\textit{stream…

Data Structures and Algorithms · Computer Science 2015-01-29 Giordano Da Lozzo , Ignaz Rutter