Covering segments with unit squares

Abstract

We study several variations of line segment covering problem with axis-parallel unit squares in IR 2 . A set S of n line segments is given. The objective is to find the minimum number of axis-parallel unit squares which cover at least one end-point of each segment. The variations depend on the orientation and length of the input segments. We prove some of these problems to be NP-complete, and give constant factor approximation algorithms for those problems. For some variations, we have polynomial time exact algorithms. For the general version of the problem, where the segments are of arbitrary length and orientation, and the squares are given as input, we propose a factor 16 approximation result based on multilevel linear programming relaxation technique, which may be useful for solving some other problems. Further, we show that our problems have connections with the problems studied by Arkin et al.[2] on conflict-free covering problem. Our NP-completeness results hold for more simplified types of objects than those of Arkin et al. [2].

A Scheduling Method of Using Multiple SAR Satellites to Observe a Large Area

“…Study [ 19 ] further investigated the issue and recomputed the lower bound when or . In addition, the problem of how to use the fewest unit squares to cover some given line segments is interesting; study [ 20 ] proved that it is an NP-Hard problem in some cases. For the first time, study [ 21 ] put a polynomial time approximation algorithm forward, using axis-parallel rectangles to cover a rectilinear polygon with holes.…”