Comparing the sizes of nondeterministic branching read-k-times programs

  • Authors:
  • E. A. Okol'nishnikova

  • Affiliations:
  • Sobolev Institute of Mathematics, Novosibirsk, 630090, Russia

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2004

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Abstract

We compare the complexities of Boolean functions for nondeterministic syntactic read-k-times branching and branching read-sk-times programs. It is shown that for each natural number k, k ≥ 2, there exists a sequence of Boolean functions such that the complexity of computation of each function of this sequence by nondeterministic syntactic branching read-k-times programs is exponentially larger (with respect to the number of variables of the Boolean function) than by nondeterministic branching read-(k ln k/ln 2 + C)-times programs, where C is a constant independent of k. Besides, it is shown that for each natural numbers N and k(N), where 4 ≤ k(N) C2 √ln N/ln ln N and C2 k and N, there exists a Boolean function in N variables such that the complexity of this function for nondeterministic syntactic read-k-times branching programs is exponentially larger (with respect to N) than for nondeterministic syntactic read-(k, ln k/ln 2 + C)-times branching programs.