Acta Informatica

, Volume 31, Issue 4, pp 315–327 | Cite as

On communication-bounded synchronized alternating finite automata

  • Oscar H. Ibarra
  • Nicholas Q. Tran
Article

Abstract

We continue the study of communication-bounded synchronized alternating finite automata (SAFA), first considered by Hromkovič et al. We show that to accept a nonregular language, an SAFA needs to generate at least Ω(log logn) communication symbols infinitely often; furthermore, a synchronized alternating finite automaton without nondeterminism (SUFA) needs to generate at leastΩ(log logn) communication symbols infinitely often for some constantk≥1. We also show that these bounds are tight.

Next, we establish dense hierarchies of these machines on the function bounding the number of communication symbols. Finally, we give a characterization of NP in terms of communication-bounded multihead synchronized alternating finite automata, namely, NP = ⋃k≥1L(SAFA(k-heads,n k -com)). This result recasts the relationships between P, NP, and PSPACE in terms of multihead synchronized alternating finite automata.

Keywords

Information System Operating System Data Structure Communication Network Information Theory 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Oscar H. Ibarra
    • 1
  • Nicholas Q. Tran
    • 1
  1. 1.Department of Computer ScienceUniversity of CaliforniaSanta BarbaraUSA

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