Abstract
We consider the following on-line pursuit-evasion problem. A team of mobile agents called searchers starts at an arbitrary node of an unknown network. Their goal is to execute a search strategy that guarantees capturing a fast and invisible intruder regardless of its movements using as few searchers as possible. As a way of modeling two-dimensional shapes, we restrict our attention to networks that are embedded into partial grids: nodes are placed on the plane at integer coordinates and only nodes at distance one can be adjacent. We give an on-line algorithm for the searchers that allows them to compute a connected and monotone strategy that guarantees searching any unknown partial grid with the use of \(O(\sqrt{n})\) searchers, where n is the number of nodes in the grid. We prove also a lower bound of \(\varOmega (\sqrt{n}/\log n)\) in terms of achievable competitive ratio of any on-line algorithm.
Research partially supported by National Science Centre (Poland) grant number 2015/17/B/ST6/01887. The full version can be found at: https://arxiv.org/abs/1610.01458.
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- 1.
In this work the terms graph and network are used exchangeably.
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Dereniowski, D., Urbańska, D. (2018). On-line Search in Two-Dimensional Environment. In: Solis-Oba, R., Fleischer, R. (eds) Approximation and Online Algorithms. WAOA 2017. Lecture Notes in Computer Science(), vol 10787. Springer, Cham. https://doi.org/10.1007/978-3-319-89441-6_17
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