Low-Dimensional Linear Programming with Violations

  • Authors:
  • Timothy M. Chan

  • Affiliations:
  • -

  • Venue:
  • FOCS '02 Proceedings of the 43rd Symposium on Foundations of Computer Science
  • Year:
  • 2002

Quantified Score

Hi-index 0.00

Visualization

Abstract

Two decades ago, Megiddo and Dyer showed that linear programming in 2 and 3 dimensions (and subsequently, any constant number of dimensions) can be solved in lineartime. In this paper, we consider linear programming with at most k violations: finding a point inside all but at most k of n given halfspaces. We give a simple algorithm in 2-d that runs in 0((n + k^2 )\log n) expected time; this is faster than earlier algorithms by Everett, Robert, and van Kreveld (1993) and Matou驴ek (1994) and is probably near-optimal for all k \ll {n \mathord{\left/ {\vphantom {n 2}} \right. \kern-\nulldelimiterspace} 2}. A (theoretical) extension of our algorithm in 3-d runs in near 0(n + k^{{{11} \mathord{\left/ {\vphantom {{11} 4}} \right. \kern-\nulldelimiterspace} 4}} n^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}}) expected time. Interestingly, the idea is based on concave-chain decompositions (or covers) of the( \leqslant k)-level, previously used in proving combinatorial k-level bounds.Applications in the plane include improved algorithms for finding a line that misclassifies the fewest among a set of bichromatic points, and finding the smallest circle enclosing all but k points. We also discuss related problems of finding local minima in levels.