5 research outputs found
Polarizationless P Systems with Active Membranes Working in the Minimally Parallel Mode
We investigate the computing power and the efficiency of P systems with
active membranes without polarizations, working in the minimally parallel mode. We
prove that such systems are computationally complete and able to solve NP-complete
problems even when the rules are of a restricted form, e.g., for establishing computational
completeness we only need rules handling single objects and no division of non-elementary
membranes is usedMinisterio de Educación y Ciencia TIN2005-09345-C04-01Junta de Andalucía TIC 58
On a Paun’s Conjecture in Membrane Systems
We study a P˘aun’s conjecture concerning the unsolvability of
NP–complete problems by polarizationless P systems with active membranes
in the usual framework, without cooperation, without priorities,
without changing labels, using evolution, communication, dissolution and
division rules, and working in maximal parallel manner. We also analyse
a version of this conjecture where we consider polarizationless P systems
working in the minimally parallel manner.Ministerio de Educación y Ciencia TIN2006–13425Junta de Andalucía TIC–58
Complexity aspects of polarizationless membrane systems
We investigate polarizationless P systems with active membranes working in
maximally parallel manner, which do not make use of evolution or communication rules, in
order to find which features are sufficient to efficiently solve computationally hard problems.
We show that such systems are able to solve the PSPACE-complete problem
QUANTIFIED 3-SAT, provided that non-elementary membrane division is controlled by the
presence of a (possibly non-elementary) membrane.Ministerio de Educación y Ciencia TIN2006-13425Junta de Andalucía TIC-58
Computing with cells: membrane systems - some complexity issues.
Membrane computing is a branch of natural computing which abstracts computing models from the structure and the functioning of the living cell. The main ingredients of membrane systems, called P systems, are (i) the membrane structure, which consists of a hierarchical arrangements of membranes which delimit compartments where (ii) multisets of symbols, called objects, evolve according to (iii) sets of rules which are localised and associated with compartments. By using the rules in a nondeterministic/deterministic maximally parallel manner, transitions between the system configurations can be obtained. A sequence of transitions is a computation of how the system is evolving. Various ways of controlling the transfer of objects from one membrane to another and applying the rules, as well as possibilities to dissolve, divide or create membranes have been studied. Membrane systems have a great potential for implementing massively concurrent systems in an efficient way that would allow us to solve currently intractable problems once future biotechnology gives way to a practical bio-realization. In this paper we survey some interesting and fundamental complexity issues such as universality vs. nonuniversality, determinism vs. nondeterminism, membrane and alphabet size hierarchies, characterizations of context-sensitive languages and other language classes and various notions of parallelism