674 research outputs found
Introducing the Concept of Activation and Blocking of Rules in the General Framework for Regulated Rewriting in Sequential Grammars
We introduce new possibilities to control the application of rules based on
the preceding application of rules which can be de ned for a general model of sequential
grammars and we show some similarities to other control mechanisms as graph-controlled
grammars and matrix grammars with and without applicability checking as well as gram-
mars with random context conditions and ordered grammars. Using both activation and
blocking of rules, in the string and in the multiset case we can show computational com-
pleteness of context-free grammars equipped with the control mechanism of activation
and blocking of rules even when using only two nonterminal symbols
One-Membrane P Systems with Activation and Blocking of Rules
We introduce new possibilities to control the application of rules based on
the preceding applications, which can be de ned in a general way for (hierarchical) P
systems and the main known derivation modes. Computational completeness can be
obtained even for one-membrane P systems with non-cooperative rules and using both
activation and blocking of rules, especially for the set modes of derivation.
When we allow the application of rules to in
uence the application of rules in previous
derivation steps, applying a non-conservative semantics for what we consider to be a
derivation step, we can even \go beyond Turing"
On the Number of Membranes in Unary P Systems
We consider P systems with a linear membrane structure working on objects
over a unary alphabet using sets of rules resembling homomorphisms. Such a
restricted variant of P systems allows for a unique minimal representation of
the generated unary language and in that way for an effective solution of the
equivalence problem. Moreover, we examine the descriptional complexity of unary
P systems with respect to the number of membranes
Cooperating Distributed Grammar Systems of Finite Index Working in Hybrid Modes
We study cooperating distributed grammar systems working in hybrid modes in
connection with the finite index restriction in two different ways: firstly, we
investigate cooperating distributed grammar systems working in hybrid modes
which characterize programmed grammars with the finite index restriction;
looking at the number of components of such systems, we obtain surprisingly
rich lattice structures for the inclusion relations between the corresponding
language families. Secondly, we impose the finite index restriction on
cooperating distributed grammar systems working in hybrid modes themselves,
which leads us to new characterizations of programmed grammars of finite index.Comment: In Proceedings AFL 2014, arXiv:1405.527
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
MOLECULAR COMPUTING WITH TEST TUBE SYSTEMS
In this paper a survey of various different theoretical models of test tube systems is given. In test tube systems specific operations are applied to the objects in their components (test tubes) in a distributed and parallel manner; the results of these computations are redistributed according to a given output/input relation using specific filters. A general theoretical framework for test tube systems is presented which is not only a theoretical basis of systems used for practical applications, but also covers the theoretical models of test tube systems based on the splicing operation as well as of test tube systems based on the operations of cutting and recombination. For test tube systems based on the operations of cutting and recombination we show that in one test tube from a finite set
of axioms and with a finite set of cutting and recombination rules only regular languages can evolve
(Tissue) P Systems with Vesicles of Multisets
We consider tissue P systems working on vesicles of multisets with the very
simple operations of insertion, deletion, and substitution of single objects.
With the whole multiset being enclosed in a vesicle, sending it to a target
cell can be indicated in those simple rules working on the multiset. As
derivation modes we consider the sequential mode, where exactly one rule is
applied in a derivation step, and the set maximal mode, where in each
derivation step a non-extendable set of rules is applied. With the set maximal
mode, computational completeness can already be obtained with tissue P systems
having a tree structure, whereas tissue P systems even with an arbitrary
communication structure are not computationally complete when working in the
sequential mode. Adding polarizations (-1, 0, 1 are sufficient) allows for
obtaining computational completeness even for tissue P systems working in the
sequential mode.Comment: In Proceedings AFL 2017, arXiv:1708.0622
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
(Tissue) P Systems Using Non-cooperative Rules Without Halting Conditions
We consider (tissue) P systems using non-cooperative rules, but considering
computations without halting conditions. As results of a computation we take the
contents of a specified output membrane/cell in each derivation step, no matter whether
this computation will ever halt or not, eventually taking only results completely consisting
of terminal objects only. The computational power of (tissue) P systems using
non-cooperative rules turns out to be equivalent to that of (E)0L systems
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