Journal of Computer and System Sciences
Membrane Computing: An Introduction
Membrane Computing: An Introduction
Theoretical Computer Science - Natural computing
The power of communication: P systems with symport/antiport
New Generation Computing
Computing with Membranes
Computationally universal P systems without priorities: two catalysts are sufficient
Theoretical Computer Science - Descriptional complexity of formal systems
On determinism versus nondeterminism in P systems
Theoretical Computer Science
Symport/Antiport P Systems with Three Objects Are Universal
Fundamenta Informaticae - Contagious Creativity - In Honor of the 80th Birthday of Professor Solomon Marcus
Relationships between nondeterministic and deterministic tape complexities
Journal of Computer and System Sciences
On model-checking of p systems
UC'05 Proceedings of the 4th international conference on Unconventional Computation
On the computational complexity of P automata
DNA'04 Proceedings of the 10th international conference on DNA computing
Theoretical Computer Science
Computing with cells: membrane systems-some complexity issues
International Journal of Parallel, Emergent and Distributed Systems
Infinite hierarchies of conformon-p systems
WMC'06 Proceedings of the 7th international conference on Membrane Computing
Some computational issues in membrane computing
MFCS'05 Proceedings of the 30th international conference on Mathematical Foundations of Computer Science
A look back at some early results in membrane computing
WMC'09 Proceedings of the 10th international conference on Membrane Computing
On Restricted Bio-Turing Machines
Fundamenta Informaticae - Theory that Counts: To Oscar Ibarra on His 70th Birthday
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We introduce a restricted model of a one-membrane symport/antiport system, called bounded S/A system. We show the following: 1. A language $L \subseteq a_1^* ... a_k^*$ is accepted by a bounded S/A system if and only if it is accepted by a log n space-bounded Turing machine. This holds for both deterministic and nondeterministic versions. 2. For every positive integer r, there is an s r and a unary language L that is accepted by a bounded S/A system with s objects that cannot be accepted by any bounded S/A system with only r objects. This holds for both deterministic and nondeterministic versions. 3. Deterministic and nondeterministic bounded S/A systems over a unary input alphabet are equivalent if and only if deterministic and nondeterministic linear-bounded automata (over an arbitrary input alphabet) are equivalent. We also introduce a restricted model of a multi-membrane S/A system, called special S/A system. The restriction guarantees that the number of objects in the system at any time during the computation remains constant. We show that for every nonnegative integer t, special S/A systems with environment alphabet E of t symbols (note that other symbols are allowed in the system if they are not transported into the environment) has an infinite hierarchy in terms of the number of membranes. Again, this holds for both deterministic and nondeterministic versions. Finally, we introduce a model of a one-membrane bounded S/A system, called bounded SA acceptor, that accepts string languages. We show that the deterministic version is strictly weaker than the nondeterministic version. Clearly, investigations into complexity issues (hierarchies, determinism versus nondeterminism, etc.) in membrane computing are natural and interesting from the points of view of foundations and applications, e.g., in modeling and simulating of cells. Some of the results above have been shown for other types of restricted P systems (that are not symport/antiport). However, these previous results do not easily translate for the models of S/A systems we consider here. In fact, in a recent article, “Further Twenty Six Open Problems in Membrane Computing” (January 26, 2005; see P Systems Web Page at http://psystems.disco.unimib.it), Gheorghe Paun poses the question of whether the earlier results, e.g., concerning determinism versus nondeterminism can be proved for restricted S/A systems.