Taishin Y. Nishida

Membrane algorithms

A new type of approximate algorithms for optimization problems, called membrane algorithms, is proposed, which can be seen as an application of membrane computing to evolutionary computing. A membrane algorithm consists of several membrane separated regions, where subalgorithms and tentative solutions to the optimization problem to be solved are placed, as well as a solution transporting mechanism between adjacent regions. The subalgorithms improve tentative solutions simultaneously. After that, the best and worst solutions in a region are sent to adjacent inner and outer regions, respectively. By repeating this process, a good solution will appear in the innermost region. The algorithm terminates if a terminate condition is satisfied. A simple condition of this type is the number of iterations, while a little more sophisticated condition becomes true if the good solution is not changed during a predetermined period. Computer experiments show that such algorithms are rather efficient in solving the travelling salesman problem.

Membrane Algorithms: Approximate Algorithms for NP-Complete Optimization Problems

A new type of approximate algorithm for optimization problems, called the membrane algorithm, is proposed. A membrane algorithm consists of several regions separated by means of membranes; in each region we place a few tentative solutions of the optimization problem and a subalgorithm. The subalgorithms improve the tentative solutions simultaneously. The best and worst solutions in a region are sent to adjacent inner and outer regions, respectively. By repeating this process, a good solution will appear in the innermost region. The algorithm terminates if a termination condition is satisfied. A simple condition is the number of iterations, while a little more sophisticated condition becomes true if the good solution is not changed during a predetermined number of iterations. Computer experiments show that the membrane algorithms solve the traveling salesman problem better than the simulated annealing algorithm.

Slender 0L languages

Abstract We present a classification of slender 0L languages into four classes and give decision methods for two of the classes. Open problems are mentioned, as well as interconnections to other areas.

A Membrane Computing Model of Photosynthesis

A model of light reactions taking place in photosynthesis is constructed using a variant of P systems. Behaviors of the model under various combinations of parameters are tested on a computer. Computer simulations show that the model explains in a good way many phenomena of photosynthesis, including photoinhibition mechanisms. A dynamical system using differential equations for photosynthesis is compared with the P system model. The comparison makes it clear that P systems are much better tools for dealing with biological phenomena than models based on differential equations.

On slender 0L languages

We give a complete proof of Theorem 3.1 in [2]. A pathological exception of Theorem 4.3 in [2] is exhibited and a condition to remove it is mentioned.

An extended Earley's algorithm for Petri net controlled grammars without λ rules and cyclic rules

In this paper we introduce an algorithm which solves the membership problem of Petri net controlled grammars without @l-rules and cyclic rules. We define a conditional tree which is a modified derivation tree of a context-free grammar with information about control by a Petri net. It is shown that a conditional tree is cancelled to a derivation tree without conditions if and only if there is a derivation under the control of the Petri net from the start symbol to a word which is the yielding of the conditional tree. Then the Earleys algorithm is extended to make a conditional tree in addition to parse a word. Thus the word is generated by a given Petri net controlled grammar if and only if the resulting conditional tree is cancelled to a tree of no condition. The time complexity of the algorithm is nondeterministic polynomial of the length of an input word. Therefore the class of languages generated by Petri net controlled grammars without @l-rules and cyclic rules is included in the class of context-sensitive languages.

Earley’s Parsing Algorithm and k-Petri Net Controlled Grammars

In this paper we modify Earley’s parsing algorithm to parse words generated by Petri net controlled grammars. Adding a vector which corresponds to a marking of a Petri net to Earley’s algorithm, it is shown that languages generated by a subclass of k-Petri net controlled grammars (introduced by J. Dassow and S. Turaev) are parsed in polynomial time of the length of a word.

Computing k-block Morphisms by Spiking Neural P Systems

In this paper we show that for every k-block morphism (k ≥ 2) there is a spiking neural P system which computes the morphism. This result generalises the result explored by G. Paun, M. Perez-Jimenez, and G. Rozenberg. We give an algorithm which constructs the spiking neural P system, that is, if a k-block morphism is given as an input, the algorithm makes rules of the spiking neural P system which computes the morphism.

Grouped partial ETOL systems and parallel multiple context-free grammars

Abstract A relation between ET0L systems and parallel multiple context-free grammars (PMCFGs) is considered. It is shown that there is a subclass of PMCFGs which is equivalent to the family of EDT0L systems. It is also shown that the family of PMCFLs (languages generated by PMCFGs) and the family of ET0L languages are mutually incomparable. A new extension of ET0L systems, grouped partial ET0L systems is defined in order to characterize PMCFLs. There is a subfamily of grouped partial EDT0L languages which coincides with the family of PMCFLs.