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Given a rectilinear domain P of h pairwise-disjoint rectilinear obstacles with a total of n vertices in the plane, we study the problem of computing bicriteria rectilinear shortest paths between two points s and t in P. Three types of bicriteria rectilinear paths are considered: minimum-link shortest paths, shortest minimum-link paths, and minimum-cost paths where the cost of a path is a non-decreasing function of both the number of edges and the length of the path. The one-point and two-point path queries are also considered. Algorithms for these problems have been given previously. Our contributions are threefold. First, we find a critical error in all previous algorithms. Second, we correct the error in a not-so-trivial way. Third, we further improve the algorithms so that they are even faster than the previous (incorrect) algorithms when h is relatively small. For example, for computing a minimum-link shortest s-t path, the previous algorithm runs in O(n log^{3/2} n) time while the time of our new algorithm is O(n + h log^{3/2} h).
@InProceedings{wang:LIPIcs.SoCG.2017.60,
author = {Wang, Haitao},
title = {{Bicriteria Rectilinear Shortest Paths among Rectilinear Obstacles in the Plane}},
booktitle = {33rd International Symposium on Computational Geometry (SoCG 2017)},
pages = {60:1--60:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-038-5},
ISSN = {1868-8969},
year = {2017},
volume = {77},
editor = {Aronov, Boris and Katz, Matthew J.},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2017.60},
URN = {urn:nbn:de:0030-drops-71876},
doi = {10.4230/LIPIcs.SoCG.2017.60},
annote = {Keywords: rectilinear paths, shortest paths, minimum-link paths, bicriteria paths, rectilinear polygons}
}