Commutative grammars: the complexity of uniform word problems
Information and Control
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
Membrane Computing: When Communication Is Enough
UMC '02 Proceedings of the Third International Conference on Unconventional Models of Computation
Membrane Systems with Symport/Antiport Rules: Universality Results
WMC-CdeA '02 Revised Papers from the International Workshop on Membrane Computing
P Systems without Priorities Are Computationally Universal
WMC-CdeA '02 Revised Papers from the International Workshop on Membrane Computing
Petri Nets, Commutative Context-Free Grammars, and Basic Parallel Processes
FCT '95 Proceedings of the 10th International Symposium on Fundamentals of Computation Theory
A partial solution to the reachability-problem for vector-addition systems
STOC '74 Proceedings of the sixth annual ACM symposium on Theory of computing
On the computational complexity of membrane systems
Theoretical Computer Science
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
Relationships between nondeterministic and deterministic tape complexities
Journal of Computer and System Sciences
On the computational complexity of P automata
DNA'04 Proceedings of the 10th international conference on DNA computing
The power of maximal parallelism in p systems
DLT'04 Proceedings of the 8th international conference on Developments in Language Theory
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Let R = {r1, ..., rk} be the set of labeled rules in a P system. We look at the computing power of the system under three semantics of parallelism. For a positive integer n ≤ k, define: n-Max-Parallel: At each step, nondeterministically select a maximal subset of at most n rules in R to apply. ≤n-Parallel: At each step, nondeterministically select any subset of at most n rules in R to apply. n-Parallel: At each step, nondeterministically select any subset of exactly n rules in R to apply. Note that in all three cases, at most one instance of any rule can be included in the selected subset. Moreover, if any rule in the subset selected is not applicable, then the whole subset is not applicable. When n = 1, the three semantics reduce to the Sequential mode. For two models of P systems that have been studied in the literature, catalytic systems and communicating P systems, we show that n-Max-Parallel mode is strictly more powerful than any of the following three modes: Sequential, ≤ n-Parallel, or n-Parallel. For example, it follows from a previous result that a 3-Max Parallel communicating P system is universal. However, under the three limited modes of parallelism, the system is equivalent to a vector addition system, which is known to only define a recursive set. This shows that gmaximal parallelismh (in the sense ofn-Max-Parallel) is key for the model to be universal. We also summarize our recent results concerning membrane hierarchy, determinism versus nondeterminism, and computational complexity of P systems. Finally, we propose some problems for future research. Some of the results presented here were obtained in collaboration with Zhe Dang and Hsu-Chun Yen.