Largest and Smallest Area Triangles on Imprecise Points

Abstract

Assume we are given a set of parallel line segments in the plane, and we wish to place a point on each line segment such that the resulting point set maximizes or minimizes the area of the largest or smallest triangle in the set. We analyze the complexity of the four resulting computational problems, and we show that three of them admit polynomial-time algorithms, while the fourth is NP-hard. Specifically, we show that maximizing the largest triangle can be done in $O(n^2)$ time (or in $O(n \log n)$ time for unit segments); minimizing the largest triangle can be done in $O(n^2 \log n)$ time; maximizing the smallest triangle is NP-hard; but minimizing the smallest triangle can be done in $O(n^2)$ time. We also discuss to what extent our results can be generalized to polygons with $k>3$ sides.