Abstract
Given a set of nonintersecting polygonal obstacles in the plane, thelink distance between two pointss andt is the minimum number of edges required to form a polygonal path connectings tot that avoids all obstacles. We present an algorithm that computes the link distance (and a corresponding minimum-link path) between two points in timeO(Eα(n) log2 n) (and spaceO(E)), wheren is the total number of edges of the obstacles,E is the size of the visibility graph, and α(n) denotes the extremely slowly growing inverse of Ackermann's function. We show how to extend our method to allow computation of a tree (rooted ats) of minimum-link paths froms to all obstacle vertices. This leads to a method of solving the query version of our problem (for query pointst).
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Communicated by Mikhail J. Atallah.
Joseph Mitchell was partially supported by NSF Grants IRI-8710858 and ECSE-8857642, and by a grant from Hughes Research Laboratories. This work was begun while Günter Rote and Gerhard Woeginger were at the Freie Universität Berlin, Fachbereich Mathematik, Institut für Informatik, and it was partially supported by the ESPRIT II Basic Research Actions Program of the EC under Contract No. 3075 (project ALCOM). Gerhard Woeginger acknowledges the support by the Fonds zur Förderung der Wissenschaftlichen Forschung, Projekt S32/01.
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Mitchell, J.S.B., Rote, G. & Woeginger, G. Minimum-link paths among obstacles in the plane. Algorithmica 8, 431–459 (1992). https://doi.org/10.1007/BF01758855
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DOI: https://doi.org/10.1007/BF01758855