61 research outputs found
On purely morphic characterizations of context-free languages
AbstractIn this paper we show the following: For any λ-free context-free language L there effectively exist a weak coding g, a homomorphism h such that L=gh−1 (∣cD2), where D2 is the Dyck set over a two-letter alphabet. As an immediate corollary it follows that for any λ-free context-free language L there exist a weak coding g and a mapping F such that L=gF−1(∣c)
On the Properties of Language Classes Defined by Bounded Reaction Automata
Reaction automata are a formal model that has been introduced to investigate
the computing powers of interactive behaviors of biochemical reactions([14]).
Reaction automata are language acceptors with multiset rewriting mechanism
whose basic frameworks are based on reaction systems introduced in [4]. In this
paper we continue the investigation of reaction automata with a focus on the
formal language theoretic properties of subclasses of reaction automata, called
linearbounded reaction automata (LRAs) and exponentially-bounded reaction
automata (ERAs). Besides LRAs, we newly introduce an extended model (denoted by
lambda-LRAs) by allowing lambda-moves in the accepting process of reaction, and
investigate the closure properties of language classes accepted by both LRAs
and lambda-LRAs. Further, we establish new relationships of language classes
accepted by LRAs and by ERAs with the Chomsky hierarchy. The main results
include the following : (i) the class of languages accepted by lambda-LRAs
forms an AFL with additional closure properties, (ii) any recursively
enumerable language can be expressed as a homomorphic image of a language
accepted by an LRA, (iii) the class of languages accepted by ERAs coincides
with the class of context-sensitive languages.Comment: 23 pages with 3 figure
Reaction Automata
Reaction systems are a formal model that has been introduced to investigate
the interactive behaviors of biochemical reactions. Based on the formal
framework of reaction systems, we propose new computing models called reaction
automata that feature (string) language acceptors with multiset manipulation as
a computing mechanism, and show that reaction automata are computationally
Turing universal. Further, some subclasses of reaction automata with space
complexity are investigated and their language classes are compared to the ones
in the Chomsky hierarchy.Comment: 19 pages, 6 figure
Membrane Computing Schema Based on String Insertions
In this note we introduce the notion of a membrane computing schema for
string objects. We propose a computing schema for a membrane network (i.e., tissue-like
membrane system) where each membrane performs unique type of operations at a time
and sends the result to others connected through the channel. The distinguished features
of the computing models obtained from the schema are:
1. only context-free insertion operations are used for string generation,
2. some membranes assume ltering functions for structured objects(molecules),
3. the generating model and accepting model are obtained in the same schema, and
both are computationally universal,
4. several known rewriting systems with universal computability can be reformulated
in terms of membrane computing schema in a uniform manner.
The rst feature provides the model with a simple uniform structure which facilitates a
biological implementation of the model, while the second feature suggests further feasibility
of the model in terms of DNA complementarity.
Through the third and fourth features, one may have a uni ed view of a variety
of existing rewriting systems with Turing computability in the framework of membrane
computing paradigm
Representations and characterizations of languages in Chomsky hierarchy by means of insertion-deletion systems
Insertion-deletion operations are much investigated in linguistics
and in DNA computing and several characterizations of Turing
computability were obtained in this framework.
In this note we contribute to this research direction with a new
characterization of this type, as well as with representations of regular
and context-free languages, mainly starting from context-free insertion
systems of as small as possible complexity. For instance, each recursively
enumerable language L can be represented in a way similar to the
celebrated Chomsky-Schützenberger representation of context-free languages,
i.e., in the form L = h(L(
) ∩D), where
is an insertion system
of weight (3, 0) (at most three symbols are inserted in a context of length
zero), h is a projection, and D is a Dyck language. A similar representation
can be obtained for regular languages, involving insertion systems
of weight (2,0) and star languages, as well as for context-free languages
– this time using insertion systems of weight (3, 0) and star languages.Ministerio de Educación y Ciencia TIN2006-1342
On spiking neural P systems
This work deals with several aspects concerning the formal verification of SN P
systems and the computing power of some variants. A methodology based on the
information given by the transition diagram associated with an SN P system is presented.
The analysis of the diagram cycles codifies invariants formulae which enable us to establish
the soundness and completeness of the system with respect to the problem it tries to resolve.
We also study the universality of asynchronous and sequential SN P systems and the
capability these models have to generate certain classes of languages. Further, by making a
slight modification to the standard SN P systems, we introduce a new variant of SN P
systems with a special I/O mode, called SN P modules, and study their computing power. It
is demonstrated that, as string language acceptors and transducers, SN P modules can
simulate several types of computing devices such as finite automata, a-finite transducers,
and systolic trellis automata.Ministerio de Educación y Ciencia TIN2006-13425Junta de Andalucía TIC-58
Spiking Neural dP Systems
We bring together two topics recently introduced in membrane computing,
the much investigated spiking neural P systems (in short, SN P systems), inspired from
the way the neurons communicate through spikes, and the dP systems (distributed P
systems, with components which "read" strings from the environment and then cooperate
in accepting their concatenation). The goal is to introduce SN dP systems, and to this
aim we first introduce SN P systems with the possibility to input, at their request, spikes
from the environment; this is done by so-called request rules. A preliminary investigation
of the obtained SN dP systems (they can also be called automata) is carried out. As
expected, request rules are useful, while the distribution in terms of dP systems can
handle languages which cannot be generated by usual SN P systems. We always work
with extended SN P systems; the non-extended case, as well as several other natural
questions remain open.Junta de Andalucía P08 – TIC 0420
Java Program Analysis Projects in Osaka University : Aspect-Based Slicing System ADAS and Ranked-Component Search System SPARS-J
Software Engineering, 2003. Proceedings. 25th International Conference onDate of Conference:3-10 May 200
Membrane Computing Schema: A New Approach to Computation Using String Insertions
In this paper, we introduce the notion of a membrane computing schema
for string objects. We propose a computing schema for a membrane network (i.e.,
tissue-like membrane system) where each membrane performs unique type of operations
at a time and sends the result to others connected through the channel. The
distinguished features of the computing models obtained from the schema are:
1. only context-free insertion operations are used for string generation,
2. some membranes assume filtering functions for structured objects (molecules),
3. generating model and accepting model are obtained in the same schema, and
both are computationally universal,
4. several known rewriting systems with universal computability can be reformulated
by the membrane computing schema in a uniform manner.
The first feature provides the model with a simple uniform structure which facilitates
a biological implementation of the model, while the second feature suggests further
feasibility of the model in terms of DNA complementarity.
Through the third and fourth features, one may have a unified view of a variety of
existing rewriting systems with Turing computability in the framework of membrane
computing paradigm.Ministerio de Educación y Ciencia TIN2006-13425Junta de Andalucía TIC-58
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