We discuss the problem of searching for an unknown line on a known or unknown line arrangement by a searcher S, and show that a search strategy exists that finds the line competitively, that is, with detour factor at most a constant when compared to the situation where S has all knowledge. In the case where S knows all lines but not which one is sought, the strategy is 79-competitive. We also show that it may be necessary to travel on Omega(n) lines to realize a constant competitive ratio. In the case where initially, S does not know any line, but learns about the ones it encounters during the search, we give a 414.2-competitive search strategy.
@InProceedings{bouts_et_al:LIPIcs.ISAAC.2018.49, author = {Bouts, Quirijn and Castermans, Thom and van Goethem, Arthur and van Kreveld, Marc and Meulemans, Wouter}, title = {{Competitive Searching for a Line on a Line Arrangement}}, booktitle = {29th International Symposium on Algorithms and Computation (ISAAC 2018)}, pages = {49:1--49:12}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-094-1}, ISSN = {1868-8969}, year = {2018}, volume = {123}, editor = {Hsu, Wen-Lian and Lee, Der-Tsai and Liao, Chung-Shou}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2018.49}, URN = {urn:nbn:de:0030-drops-99970}, doi = {10.4230/LIPIcs.ISAAC.2018.49}, annote = {Keywords: Competitive searching, line arrangement, detour factor, search strategy} }
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