IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

In this paper we give a brief survey of some variants of P systems and their computational capacity. An improvement of a known result about rewriting P systems with leftmost derivation is given. We also give the generalized definition for normal forms of rewriting P systems. © Springer-Verlag Berlin Heidelberg 2003.

Department of Computer Science and Engineering

GENERAL

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

A survey of some variants of P systems

We consider array languages (sets of pictures consisting of symbols placed in the lattice points of the 2D grid) and the possibility to handle them with P systems. After proving binary normal forms for array matrix grammars (which, even in the case when no appearance checking is used, are known to generate the array languages of arbitrary array grammars), we prove that the P systems with context-free rules (with three membranes and no control on the communication or the use of rules) are computationally universal, able to generate all computable array languages. Some open problems are also formulated. © 2003 Kluwer Academic Publishers.

Natural Computing

Array-rewriting P systems

In this paper, we propose a class of P automata in which each membrane has a state, like in tissue P systems [5], and the computation starts at some initial state and ends in a final state. Unlike the automaton considered in [2], where rules are used in sequential manner, here we consider a variant such that the rules can be applied in maximal mode (as defined in tissue P systems). We show that P automata characterize the recursively enumerable sets of vectors of natural numbers.

International Journal of Computer Mathematics

On a class of P automata

In this paper we define a variant of P systems, namely, probabilistic rewriting P systems, where the selection of rewriting rules is probabilistic. We show that, with non-zero cut-point, probabilistic rewriting P systems with/without priorities generate only finite languages, but with zero cut/point and without priorities, probabilistic rewriting P systems of degree 1 characterize the family of languages generated by matrix grammars. We also prove that probabilistic rewriting P systems of degree 1 with zero cut-point and priorities characterize recursively enumerable languages. © 2003 World Scientific Publishing Company.

International Journal of Foundations of Computer Science

Probabilistic rewriting p systems

Designing chips for lower power applications is one of the most important challenges faced by the VLSI designers. Since the power consumed by I/O pins of a CPU is a significant source of power consumption, work has been done on developing encoding schemes for reducing switching activity on external buses. In this paper we propose a new coding technique, namely, the Dynamic Coding Scheme, for low-power data bus. Our method considers two logical groupings of the bus lines, each being a permutation of the bus lines, and dynamically selects that grouping which yields the minimum number of transitions. © 2003 IEEE.

Proceedings of IEEE Computer Society Annual Symposium on VLSI, ISVLSI

Dynamic coding technique for low-power data bus

Generally, in P systems with string-objects one uses the Chomsky way of rewriting for processing the objects. In this paper we consider the contextual way of handling string-objects in P systems. We introduce some variants of contextual grammars and prove that contextual P systems with rules corresponding to these variants are more powerful than ordinary contextual grammars and their variants. We also show that one-sided contextual P systems with right-sided erased contexts and insertion contextual P systems with right-sided erased contexts are computationally complete.

Fundamenta Informaticae

Contextual P systems

Generally, in rewriting P systems (Martin-Vide and Pǎun, 2000) one uses Chomsky rules (Hopcroft and Ullman, 1979), whereas in contextual P systems (Madhu and Krithivasan, 2002) we considered contextual rules (Marcus, 1969), (Pǎun, 1997) for processing string-objects. By combining Chomsky rules and contextual rules, a new class of P systems were introduced in Krishna et al. (2001), the hybrid P systems. In this paper we continue the study of hybrid P systems, and show that systems with two membranes are universal in the case of contextual rules with a regular choice, and systems with four membranes are universal in the case of contextual rules with finite selection.

Grammars

A note on hybrid P systems

P systems, introduced by Gh. Păun form a new class of distributed computing model. Several variants of Psystems were already shown to be computationally universal. In this paper, we propose a new variant of Psystems, P systems with membrane creation, in which some objects are productive and create membranes. This new variant of Psystems is capable of solving the Hamiltonian Path Problem in linear time. We show that Psystems with membrane creation are computationally complete.

World University root node

International Conference on Machines, Computations, and Universality

P Systems with Membrane Creation: Universality and Efficiency

P systems, introduced by Gh. Pǎaun, form a new class of distributed computing models. Many variants of P systems were shown to be computationally universal. In this paper, we consider several classes of P systems with symbol-objects where we allow the catalysts to move in and out of a membrane. We prove universality results for these variants of P systems with a very small number of membranes.&nbsp;