Showing papers by "Nicola Santoro published in 1989"

Efficient elections in chordal ring networks

Abstract: We study the message complexity of the problem of distributively electing a leader in chordal rings. Such networks consist of a basic ring with additional links, the extreme cases being the oriented ring and the complete graph with a full sense of direction. We present a general election algorithm for these networks, and prove its optimality. As a corollary, we show thatO(logn) chords at each processor suffice to obtain an algorithm that uses at mostO(n) messages; this improves and extends a previous work, where an algorithm, also usingO(n) messages, was suggested for the case where alln-1 chords exist (the oriented complete network).

Reduction techniques for selection in distributed files

Abstract: The problem of selecting the Kth smallest element of a set of N elements distributed among d sites of a communication network is examined. A reduction technique is a distributed algorithm that transforms this problem to an equivalent one where either K or N (or both) are reduced. A collection of distributed reduction techniques is presented; the combined use of the algorithms offers new solutions for the selection problem in shout-echo networks and in a class of point-to-point networks. The communication complexity of these solutions is analyzed and shown to represent an improvement on the multiplicative constant of existing bounds for those networks. >

Geometric containment and partial orders

Abstract: Given two geometric sets A and B, it is said that A is containable in B provided A is isometric to a subset of B. Containability induces a partial order on any set of geometric figures, such as rectangles in the plane. A recent result states that for the set of rectangles in the plane, the containability partial order is of countably infinite dimension. In this paper the rectangle result is extended to other families of geometric figures and to a partial order obtained from quadratic polynomials.