A randomized competitive algorithm for evaluating priced AND/OR trees

  • Authors:
  • Eduardo Sany Laber

  • Affiliations:
  • Departamento de Informática da PUC-Rio, 22453901 Rio de Janeiro, RJ, Brazil

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2008

Quantified Score

Hi-index 5.23

Visualization

Abstract

Recently, Charikar et al. investigated the problem of evaluating AND/OR trees, with non-uniform costs on its leaves, from the perspective of the competitive analysis. For an AND/OR tree T they presented a @m(T)-competitive deterministic polynomial time algorithm, where @m(T) is the number of leaves that must be read, in the worst case, in order to determine the value of T. Furthermore, they proved that @m(T) is a lower bound on the deterministic competitiveness, which assures the optimality of their algorithm. The power of randomization in this context has remained as an open question. Here, we take a step towards solving this problem by presenting a 56@m(T)-competitive randomized polynomial time algorithm. This contrasts with the best known lower bound @m(T)/2.