Abstract
In P systems with active membranes, the question of understanding the power of non-confluence within a polynomial time bound is still an open problem. It is known that, for shallow P systems, that is, with only one level of nesting, non-confluence allows them to solve conjecturally harder problems than confluent P systems, thus reaching \(\mathbf{PSPACE }\). Here we show that \(\mathbf{PSPACE }\) is not only a bound, but actually an exact characterization. Therefore, the power endowed by non-confluence to shallow P systems is equal to the power gained by confluent P systems when non-elementary membrane division and polynomial depth are allowed, thus suggesting a connection between the roles of non-confluence and nesting depth.
Similar content being viewed by others
References
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. Simulating elementary active membranes, with an application to the P conjecture. In: Gheorghe M, Rozenberg G, Sosík P, Zandron C, editors. Membrane computing, 15th International conference, CMC 2014, lecture notes in computer science, vol. 8961. New York: Springer; 2014. p. 284–99.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. Membrane division, oracles, and the counting hierarchy. Fund Inf. 2015;138(1–2):97–111.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. Monodirectional P systems. Nat Comput. 2016;15(4):551–64.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. The counting power of P systems with antimatter. Theor Comput Sci. 2017;701:161–73.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. Shallow non-confluent P systems. In: Leporati A, Rozenberg G, Salomaa A, Zandron C, editors. Membrane computing, 17th international conference, CMC 2016. Lecture notes in computer science, vol. 10105. New York: Springer; 2017. p. 307–16.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. A toolbox for simpler active membrane algorithms. Theor Comput Sci. 2017;673:42–57.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. Solving QSAT in sublinear depth. In: Hinze T, Rozenberg G, Salomaa A, Zandron C editors. Membrane computing, CMC 2018. Lecture notes in computer science, vol 11399. Cham: Springer; 2019.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. Subroutines in P systems and closure properties of their complexity classes. Theor Comput Sci. 2018.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. A survey on space complexity of P systems with active membranes. Int J Adv in Eng Sci Appl Math. 2018;10(3):221–9.
Leporati A, Manzoni L, Mauri G, Porreca AE, Zandron C. Characterising the complexity of tissue P systems with fission rules. J Comput Syst Sci. 2017;90:115–28.
Murphy N, Woods D. The computational power of membrane systems under tight uniformity conditions. Nat Comput. 2011;10(1):613–32.
Păun Gh, Rozenberg G, Salomaa A, editors. The Oxford handbook of membrane computing. Oxford: Oxford University Press; 2010.
Pérez-Jiménez MJ, Romero-Jiménez A, Sancho-Caparrini F. Complexity classes in models of cellular computing with membranes. Nat Comput. 2003;2(3):265–84.
Porreca AE, Leporati A, Mauri G, Zandron C. Recent complexity-theoretic results on P systems with active membranes. J Logic Comput. 2015;25(4):1047–71.
Porreca AE, Mauri G, Zandron C. Non-confluence in divisionless P systems with active membranes. Theor Comput Sci. 2010;411(6):878–87.
Sosík P. The computational power of cell division in P systems: Beating down parallel computers? Nat Comput. 2003;2(3):287–98.
Sosík P, Rodríguez-Patón A. Membrane computing and complexity theory: a characterization of PSPACE. J Comput Syst Sci. 2007;73(1):137–52.
Zandron C, Ferretti C, Mauri G. Solving NP-complete problems using P systems with active membranes. In: Antoniou I, Calude CS, Dinneen MJ, editors. Unconventional models of computation, UMC’2K, proceedings of the second international conference. New York: Springer; 2001. p. 289–301.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Leporati, A., Manzoni, L., Mauri, G. et al. Characterizing PSPACE with shallow non-confluent P systems. J Membr Comput 1, 75–84 (2019). https://doi.org/10.1007/s41965-019-00011-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s41965-019-00011-4