Computing shortest paths in the plane with removable obstacles

PK Agarwal, N Kumar, S Sintos… - … and Workshops on …, 2018 - drops.dagstuhl.de
16th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT …, 2018drops.dagstuhl.de
We consider the problem of computing a Euclidean shortest path in the presence of
removable obstacles in the plane. In particular, we have a collection of pairwise-disjoint
polygonal obstacles, each of which may be removed at some cost c_i> 0. Given a cost
budget C> 0, and a pair of points s, t, which obstacles should be removed to minimize the
path length from s to t in the remaining workspace? We show that this problem is NP-hard
even if the obstacles are vertical line segments. Our main result is a fully-polynomial time …
Abstract
We consider the problem of computing a Euclidean shortest path in the presence of removable obstacles in the plane. In particular, we have a collection of pairwise-disjoint polygonal obstacles, each of which may be removed at some cost c_i> 0. Given a cost budget C> 0, and a pair of points s, t, which obstacles should be removed to minimize the path length from s to t in the remaining workspace? We show that this problem is NP-hard even if the obstacles are vertical line segments. Our main result is a fully-polynomial time approximation scheme (FPTAS) for the case of convex polygons. Specifically, we compute an (1+ epsilon)-approximate shortest path in time O ({nh}/{epsilon^ 2} log n log n/epsilon) with removal cost at most (1+ epsilon) C, where h is the number of obstacles, n is the total number of obstacle vertices, and epsilon in (0, 1) is a user-specified parameter. Our approximation scheme also solves a shortest path problem for a stochastic model of obstacles, where each obstacle's presence is an independent event with a known probability. Finally, we also present a data structure that can answer st path queries in polylogarithmic time, for any pair of points s, t in the plane.
drops.dagstuhl.de
以上显示的是最相近的搜索结果。 查看全部搜索结果