2,215 research outputs found
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
Playing with Derivation Modes and Halting Conditions
In the area of P systems, besides the standard maximally parallel derivation
mode, many other derivation modes have been investigated, too. In this paper, many
variants of hierarchical P systems and tissue P systems using different derivation modes
are considered and the effects of using di erent derivation modes, especially the maximally
parallel derivation modes and the maximally parallel set derivation modes, on the
generative and accepting power are illustrated. Moreover, an overview on some control
mechanisms used for (tissue) P systems is given.
Furthermore, besides the standard total halting mode, we also consider different halting
conditions such as unconditional halting and partial halting and explain how the use
of different halting modes may considerably change the computing power of P systems
and tissue P systems
Particular Results for Variants of P Systems with One Catalyst in One Membrane
Purely catalytic P systems can generate all recursively enumerable sets of
natural numbers with only three catalysts in one membrane, whereas we know that one
catalyst in one membrane is not enough. On the other hand, P systems also allowing
(non-catalytic) non-cooperative evolution rules with only two catalysts in one membrane
are already computationally complete, too. We here investigate special variants of P
systems with only one catalyst in one membrane that are not computationally complete,
i.e., variants of P systems with only one catalyst in one membrane that cannot generate
all recursively enumerable sets of natural numbers
On Controlled P Systems
We introduce and brie
y investigate P systems with controlled computations.
First, P systems with label restricted transitions are considered (in each step, all
rules used have either the same label, or, possibly, the empty label, ), then P systems
with the computations controlled by languages (as in context-free controlled grammars).
The relationships between the families of sets of numbers computed by the various classes
of controlled P systems are investigated, also comparing them with length sets of languages
in Chomsky and Lindenmayer hierarchies (characterizations of the length sets of
ET0L and of recursively enumerable languages are obtained in this framework). A series
of open problems and research topics are formulated
Purely Catalytic P Systems over Integers and Their Generative Power
We further investigate the computing power of the recently introduced P
systems with Z-multisets (also known as hybrid sets) as generative devices. These systems
apply catalytic rules in the maximally parallel way, even consuming absent non-catalysts,
e ectively generating vectors of arbitrary (not just non-negative) integers. The rules may
be made inapplicable only by dissolution rules. However, this releases the catalysts into
the immediately outer region, where new rules might become applicable to them. We
discuss the generative power of this model. Finally, we consider the variant with mobile
catalysts
Priorities, Promoters and Inhibitors in Deterministic Non-Cooperative P Systems
Membrane systems (with symbol objects) are distributed controlled multiset
processing systems. Non-cooperative P systems with either promoters or inhibitors (of
weight not restricted to one) are known to be computationally complete. Since recently,
it is known that the power of the deterministic subclass of such systems is subregular. We
present new results on the weight of promoters and inhibitors, as well as for characterizing
the systems with priorities only
P Systems with Anti-Matter
After a short introduction to the area of membrane computing (a branch
of natural computing), we introduce the concept of anti-matter in membrane computing.
First we consider spiking neural P systems with anti-spikes, and then we show the
power of anti-matter in cell-like P systems. As expected, the use of anti-matter objects
and especially of matter/anti-matter annihilation rules, turns out to be rather powerful:
computational completeness of P systems with anti-matter is obtained immediately, even
without using catalysts. Finally, some open problems are formulated, too
Languages and P Systems: Recent Developments
Languages appeared from the very beginning in membrane computing, by
their length sets or directly as sets of strings. We briefly recall here this relationship, with
some details about certain recent developments. In particular, we discuss the possibility
to associate a control word with a computation in a P system. An improvement of a result
concerning the control words of spiking neural P systems is given: regular languages can
be obtained as control words of such systems with only four neurons (and with usual
extended rules: no more spikes are produces than consumed). Several research topics are
pointed out.Junta de Andalucía P08 – TIC 0420
26. Theorietag Automaten und Formale Sprachen 23. Jahrestagung Logik in der Informatik: Tagungsband
Der Theorietag ist die Jahrestagung der Fachgruppe Automaten und Formale Sprachen der Gesellschaft für Informatik und fand erstmals 1991 in Magdeburg statt. Seit dem Jahr 1996 wird der Theorietag von einem eintägigen Workshop mit eingeladenen Vorträgen begleitet. Die Jahrestagung der Fachgruppe Logik in der Informatik der Gesellschaft für Informatik fand erstmals 1993 in Leipzig statt. Im Laufe beider Jahrestagungen finden auch die jährliche Fachgruppensitzungen statt. In diesem Jahr wird der Theorietag der Fachgruppe Automaten und Formale Sprachen erstmalig zusammen mit der Jahrestagung der Fachgruppe Logik in der Informatik abgehalten. Organisiert wurde die gemeinsame Veranstaltung von der Arbeitsgruppe Zuverlässige Systeme des Instituts für Informatik an der Christian-Albrechts-Universität Kiel vom 4. bis 7. Oktober im Tagungshotel Tannenfelde bei Neumünster. Während des Tre↵ens wird ein Workshop für alle Interessierten statt finden. In Tannenfelde werden • Christoph Löding (Aachen) • Tomás Masopust (Dresden) • Henning Schnoor (Kiel) • Nicole Schweikardt (Berlin) • Georg Zetzsche (Paris) eingeladene Vorträge zu ihrer aktuellen Arbeit halten. Darüber hinaus werden 26 Vorträge von Teilnehmern und Teilnehmerinnen gehalten, 17 auf dem Theorietag Automaten und formale Sprachen und neun auf der Jahrestagung Logik in der Informatik. Der vorliegende Band enthält Kurzfassungen aller Beiträge. Wir danken der Gesellschaft für Informatik, der Christian-Albrechts-Universität zu Kiel und dem Tagungshotel Tannenfelde für die Unterstützung dieses Theorietags. Ein besonderer Dank geht an das Organisationsteam: Maike Bradler, Philipp Sieweck, Joel Day. Kiel, Oktober 2016 Florin Manea, Dirk Nowotka und Thomas Wilk
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