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We study online competitive algorithms for the \emph{line chasing problem} in Euclidean spaces $\reals^d$, where the input consists of an initial point $P_0$ and a sequence of lines $X_1,X_2,...,X_m$, revealed one at a time. At each step…

Data Structures and Algorithms · Computer Science 2019-09-23 Marcin Bienkowski , Jarosław Byrka , Marek Chrobak , Christian Coester , Łukasz Jeż , Elias Koutsoupias

We study a variant of the searching problem where the environment consists of a known terrain and the goal is to obtain visibility of an unknown target point on the surface of the terrain. The searcher starts on the surface of the terrain…

Computational Geometry · Computer Science 2024-01-03 Sarita de Berg , Nathan van Beusekom , Max van Mulken , Kevin Verbeek , Jules Wulms

We consider three related problems of robot movement in arbitrary dimensions: coverage, search, and navigation. For each problem, a spherical robot is asked to accomplish a motion-related task in an unknown environment whose geometry is…

Computational Geometry · Computer Science 2011-10-13 Joshua Brown Kramer , Lucas Sabalka

In the online matching on the line problem, the task is to match a set of requests $R$ online to a given set of servers $S$. The distance metric between any two points in $R\,\cup\, S$ is a line metric and the objective for the online…

Data Structures and Algorithms · Computer Science 2017-12-20 Antonios Antoniadis , Carsten Fischer , Andreas Tönnis

We give an improved lower bound of 10/3 on the competitive ratio for the exploration of an undirected, edge-weighted graph with a single agent that needs to return to the starting location after visiting all vertices. We assume that the…

Data Structures and Algorithms · Computer Science 2020-02-26 Alexander Birx , Yann Disser , Alexander V. Hopp , Christina Karousatou

We revisit the problem of searching for a target at an unknown location on a line when given upper and lower bounds on the distance D that separates the initial position of the searcher from the target. Prior to this work, only asymptotic…

Data Structures and Algorithms · Computer Science 2013-10-04 Prosenjit Bose , Jean-Lou De Carufel , Stephane Durocher

We study a fundamental cooperative message-delivery problem on the plane. Assume $n$ robots which can move in any direction, are placed arbitrarily on the plane. Robots each have their own maximum speed and can communicate with each other…

Distributed, Parallel, and Cluster Computing · Computer Science 2021-09-28 Jared Coleman , Evangelos Kranakis , Danny Krizanc , Oscar Morales-Ponce

We consider the problem of searching for rays (or lines) in the half-plane. The given problem turns out to be a very natural extension of the cow-path problem that is lifted into the half-plane and the problem can also directly be motivated…

Computational Geometry · Computer Science 2025-12-19 Elmar Langetepe , Florian Gans

We study the Symmetric Rendezvous Search Problem for a multi-robot system. There are $n>2$ robots arbitrarily located on a line. Their goal is to meet somewhere on the line as quickly as possible. The robots do not know the initial location…

Robotics · Computer Science 2022-01-04 Deniz Ozsoyeller , Pratap Tokekar

We consider the open, non-preemptive online Dial-a-Ride problem on the real line, where transportation requests appear over time and need to be served by a single server. We give a lower bound of 2.0585 on the competitive ratio, which is…

Optimization and Control · Mathematics 2019-07-08 Alexander Birx , Yann Disser , Kevin Schewior

Computing lower and upper bounds on the competitive ratio of online algorithms is a challenging question: For a minimization combinatorial problem, proving a competitive ratio for a given algorithm leads to an upper bound. However computing…

Computer Science and Game Theory · Computer Science 2022-12-19 Antoine Lhomme , Olivier Romane , Nicolas Catusse , Nadia Brauner

The problem of scheduling unrelated machines by a truthful mechanism to minimize the makespan was introduced in the seminal "Algorithmic Mechanism Design" paper by Nisan and Ronen. Nisan and Ronen showed that there is a truthful mechanism…

Computer Science and Game Theory · Computer Science 2020-11-17 Shahar Dobzinski , Ariel Shaulker

Cooperation between mobile robots and wireless sensor networks is a line of research that is currently attracting a lot of attention. In this context, we study the following problem of barrier coverage by stationary wireless sensors that…

Data Structures and Algorithms · Computer Science 2014-10-27 J. Czyzowicz , E. Kranakis , D. Krizanc , L. Narayanan , J. Opatrny

We consider the problem of finding a door along a wall with a blind robot that neither knows the distance to the door nor the direction towards of the door. This problem can be solved with the well-known doubling strategy yielding an…

Computational Geometry · Computer Science 2010-12-24 Tom Kamphans , Elmar Langetepe

We revisit the linear search problem where a robot, initially placed at the origin on an infinite line, tries to locate a stationary target placed at an unknown position on the line. Unlike previous studies, in which the robot travels along…

Data Structures and Algorithms · Computer Science 2017-01-12 Jurek Czyzowicz , Evangelos Kranakis , Danny Krizanc , Lata Narayanan , Jaroslav Opatrny , Sunil Shende

We consider a fundamental problem concerning the deployment of a wireless robotic network: to fulfill various end-to-end performance requirements, a "sufficient" number of robotic relays must be deployed to ensure that links are of…

Robotics · Computer Science 2016-11-28 Pradipta Ghosh , Bhaskar Krishnamachari

In this paper, we study two variants of the online metric matching problem. The first problem is the online metric matching problem where all the servers are placed at one of two positions in the metric space. We show that a simple greedy…

Data Structures and Algorithms · Computer Science 2020-10-01 Toshiya Itoh , Shuichi Miyazaki , Makoto Satake

We consider competitive algorithms for adaptive group testing problems. In the first part of the paper, we develop an algorithm with competitive constant c < 1.452 thus improving the up to now best known algorithms with constants…

Combinatorics · Mathematics 2020-12-07 Robert Scheidweiler , Eberhard Triesch

We study a problem of online targets coverage by a drone or a sensor that is equipped with a camera or an antenna of fixed half-angle of view $\alpha$. The targets to be monitored appear at arbitrary positions on a line barrier in an online…

Data Structures and Algorithms · Computer Science 2026-04-06 Stefan Dobrev , Konstantinos Georgiou , Evangelos Kranakis , Danny Krizanc , Lata Narayanan , Jaroslav Opatrny , Denis Pankratov , Sunil Shende

There are $n\geq 3$ unit speed mobile agents placed at the origin of the infinite line. In as little time as possible, the agents must find and evacuate from an exit placed at an initially unknown location on the line. The agents can…

Data Structures and Algorithms · Computer Science 2026-05-12 J. Czyzowicz , R. Killick , E. Kranakis , G. Stachowiak
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