Maintenance of geometric extrema ∈

  • Authors:
  • David Dobkin;Subhash Suri

  • Affiliations:
  • Princeton Univ., Princeton, NJ;Bell Communications Research, Morristown, NJ

  • Venue:
  • Journal of the ACM (JACM)
  • Year:
  • 1991

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Abstract

Let S be a set, f: S×S→R+ a bivariate function, and f(x,S) the maximum value of f(x,y) over all elements y∈S. We say that f is decomposable with respect with the maximum if f(x,S) = max {f(x,S1),f(x,S2),…,f(x,Sk)} for any decomposition S = &mgr;i=1i=kSi. Computing the maximum (minimum) value of a decomposable function is inherent in many problems of computational geometry and robotics. In this paper, a general technique is presented for updating the maximum (minimum) value of a decomposable function as elements are inserted into and deleted from the set S. Our result holds for a semi-online model of dynamization: When an element is inserted, we are told how long it will stay. Applications of this technique include efficient algorithms for dynamically computing the diameter or closest pair of a set of points, minimum separation among a set of rectangles, smallest distance between a set of points and a set of hyperplanes, and largest or smallest area (perimeter) retangles determined by a set of points. These problems are fundamental to application areas such as robotics, VLSI masking, and optimization.