On Symport/Antiport P Systems with One or Two Symbols

  • Authors:
  • Oscar H. Ibarra;Sara Woodworth

  • Affiliations:
  • University of California at Santa Barbara;University of California at Santa Barbara

  • Venue:
  • SYNASC '05 Proceedings of the Seventh International Symposium on Symbolic and Numeric Algorithms for Scientific Computing
  • Year:
  • 2005

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Abstract

We look at the computational power of symport/antiport system (SA) acceptors and generators with small numbers of membranes and objects. We show that even with a single object and only three membranes, a SA acceptor can accept the nonsemilinear set L = {2ⁿ∣n ≥ 0}. L can also be accepted with two objects and only one membrane. This latter model can accept all unary semilinear (i.e., regular) sets. We also show that for any k ≥ 1, the class of sets of k-tuples of nonnegative integers accepted by partially blind (multi-) counter machines is a subclass of the class of sets of k-tuples accepted by 1-object multi-membrane SA acceptors. Similarly, the class of sets of k-tuples of nonnegative integers generated by partially blind counter machines is a subclass of the class of sets of k-tuples generated by 1-objectmulti-membrane SA generators. As a corollary, the unary semilinear sets are a proper subclass of the unary sets of numbers accepted by SA acceptors with one object and 8 membranes. Whether or not 1-object multi-membrane SA acceptors (resp., generators) are universal remains an interesting open question.