A New Balanced Subdivision of a Simple Polygon for Time-Space Trade-off Algorithms

2017/09/28 by Oh, Eunjin, Ahn, Hee-Kap
#Computational Geometry (cs.CG) #FOS: Computer and information sciences

paper · doi:10.48550/arxiv.1709.09932

Abstract

We are given a read-only memory for input and a write-only stream for output. For a positive integer parameter s, an s-workspace algorithm is an algorithm using only O(s) words of workspace in addition to the memory for input. In this paper, we present an O(n²/s)-time s-workspace algorithm for subdividing a simple polygon into O(min\n/s,s\) subpolygons of complexity O(max\n/s,s\). As applications of the subdivision, the previously best known time-space trade-offs for the following three geometric problems are improved immediately: (1) computing the shortest path between two points inside a simple n-gon, (2) computing the shortest path tree from a point inside a simple n-gon, (3) computing a triangulation of a simple n-gon. In addition, we improve the algorithm for the second problem even further.

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