Two robots patrolling on a line: Integer version and approximability
Paper in proceeding, 2020

Suppose that two robots can move at unit speed on a line and must visit certain points called stations infinitely often. Every station allows some maximal waiting time between two visits. The problem is to construct an optimal schedule for the robots. While the one-robot problem is easy to solve in linear time, already for two robots the complexity is open. Chuangpishit, Czyzowicz, Gasieniec, Georgiou, Jurdzinski, and Kranakis (SOFSEM 2018) found a√3-approximation algorithm. Here we provide a PTAS, accomplished by rounding and (perhaps more surpris-ingly) by using the well-quasi ordering of vectors of positive integers. The result is not very practical in the present form, but further investigation of the integer version may make it more usable

approximation scheme

well-quasi ordering



Peter Damaschke

Chalmers, Computer Science and Engineering (Chalmers), Data Science

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

03029743 (ISSN) 16113349 (eISSN)

Vol. 12126 LNC 211-223
9783030489656 (ISBN)

31st International Workshop on Combinatorial Algorithms IWOCA 2020
Bordeaux, France,


Basic sciences

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Computer Science



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