Computationally universal P systems without priorities: two catalysts are sufficient

  • Authors:

  • Rudolf Freund;Lila Kari;Marion Oswald;Petr Sosík

  • Affiliations:

  • Faculty of Informatics, Vienna University of Technology, Favoritenstra. 9-11, A-1040 Vienna, Austria;Department of Computer Science, The University of Western Ontario, London, Ont., Canada, N6A 5B7;Faculty of Informatics, Vienna University of Technology, Favoritenstra. 9-11, A-1040 Vienna, Austria;Department of Computer Science, The University of Western Ontario, London, Ont., Canada, N6A 5B7 and Institute of Computer Science, Silesian University, Opava, Czech Republic

  • Venue:
  • Theoretical Computer Science - Descriptional complexity of formal systems
  • Year:
  • 2005

Quantified Score

Hi-index 0.00

Visualization

Abstract

The original model of P systems with symbol objects introduced by Paun was shown to be computationally universal, provided that catalysts and priorities of rules are used. By reduction via register machines Sosík and Freund proved that the priorities may be omitted from the model without loss of computational power. Freund, Oswald, and Sosík considered several variants of P systems with catalysts (but without priorities) and investigated the number of catalysts needed for these specific variants to be computationally universal. It was shown that for the classic model of P systems with the minimal number of two membranes the number of catalysts can be reduced from six to five; using the idea of final states the number of catalysts could even be reduced to four. In this paper we are able to reduce the number of catalysts again: two catalysts are already sufficient. For extended P systems we even need only one membrane and two catalysts. For the (purely) catalytic systems considered by Ibarra only three catalysts are already enough.