scispace - formally typeset
Search or ask a question

Showing papers by "Kamala Krithivasan published in 2013"


01 Jan 2013
TL;DR: 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 set of ET0L and of recursively enumerable languages.
Abstract: We introduce and briefly 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, λ, 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.

15 citations


Book ChapterDOI
01 Jan 2013
TL;DR: A new way of associating a language with the computation of a P system, where the labels are chosen from a finite alphabet or \(\lambda .\) is considered, that associates a string that is obtained by concatenating the labels of the rules in the transition sequence corresponding to a computation.
Abstract: A new way of associating a language with the computation of a P system is considered. A label is assigned to every rule in a P system, where the labels are chosen from a finite alphabet or \(\lambda .\) We associate a string, called control word, that is obtained by concatenating the labels of the rules in the transition sequence corresponding to a computation. We study the generative capacity of such control languages comparing them with family of languages such as regular, context-free, context-sensitive and recursively enumerable languages of Chomskian hierarchy.

11 citations


Book ChapterDOI
01 Jul 2013
TL;DR: This work considers a way to associate a language with the computations of a tissue P system, and assigns a label to every rule, where the labels are chosen from an alphabet or the label can be λ.
Abstract: We consider a way to associate a language with the computations of a tissue P system. We assign a label to every rule, where the labels are chosen from an alphabet or the label can be λ. The rules used in a transition should have either the empty label or the same label from the chosen alphabet. In this way, a string is associated with each halting computation, called the control word of the computation. The set of all control words associated with computations in a tP system form the control language of the system. We study the family of control languages of tP systems in comparison with the families of finite, regular, context-free, context-sensitive, and recursively enumerable languages.

10 citations


Journal ArticleDOI
TL;DR: This work defines normal-forms of binding-blocking automata for one of its variants and shows that the acceptance power of this variant of BBA is strictly less than that of multi-head finite automata.
Abstract: We propose an automaton model called as binding-blocking automaton BBA. It is a finite state automaton together with the ability to block some symbols and postpone them for reading by the head at a later time. The idea of blocking some symbols from being read by the head and unblocking when the system requires to read is motivated by peptide computing where some parts of peptide sequences are blocked by attaching an antibody with higher affinity and unblocked at a later point by the removal of the appropriate antibody. We study the variants of such systems, analyse the power of each variants and show various hierarchy results involving them. We also define normal-forms of binding-blocking automata for one of its variants and also show that the acceptance power of this variant of BBA is strictly less than that of multi-head finite automata.

3 citations


Journal Article
TL;DR: It is interesting to note that the regular control on thc tables of Part DLTOLAS will not increase the generative capacity of Part DETOLAS.
Abstract: Regular, context-free and context-sensitive controls are imposed on the tables of TOLAS and the hierarchy established. The effect of control with appearance checking and minimal table interpretations are investigated over the tables of Part ETOLAS.It is interesting to note that the regular control on thc tables of Part DLTOLAS will not increase the generative capacity of Part DETOLAS.

2 citations


Journal Article
TL;DR: This paper considers bottom-up tree automata and discusses the sequential distributed version of this model, and finds that the ∗- mode does not increase the power, whereas the other modes increase thePower.
Abstract: Tree automata have been defined to accept trees. Different types of acceptance like bottom-up, top-down, tree walking have been considered in the literature. In this paper, we consider bottom-up tree automata and discuss the sequential distributed version of this model. Generally, this type of distribution is called cooperative distributed automata or the blackboard model. We define the traditional five modes of cooperation, viz. ∗-mode, t-mode, = k, ≥ k, ≤ k (k ≥ 1) modes on bottom-up tree automata. We discuss the accepting power of cooperative distributed tree automata under these modes of cooperation. We find that the ∗- mode does not increase the power, whereas the other modes increase the power. We discuss a few results comparing the acceptance power under different modes of cooperation.

2 citations


Proceedings ArticleDOI
01 Dec 2013
TL;DR: A heuristic approach to the distance realization problem, which arises in Network Tomography, which attempts to maximize the `entropy of betweenness-centrality' measure in the network while satisfying the distance constraints.
Abstract: This paper proposes a heuristic approach for the distance realization problem, which arises in Network Tomography Network Tomography is the study of estimating internal network structure and link-level performance from end-to-end measurements A distance realization problem is to reconstruct a graph or topology from its distance matrix, ie, the matrix containing the pairwise distances between the terminal nodes The graph, thus realized from the pairwise distances of terminal nodes, can either be a tree or a general graph There are efficient polynomial algorithms developed for the case of tree realization However, the problem of finding optimal realization (ie, the total length of the graph realized is minimum) of distance matrix for a general graph is shown to be NP-hard Our proposed heuristic approach for distance realization consists of three stages: (i) find a closer tree realizable distance matrix based on the shortest paths, (ii) construct a tree and (iii) fix the differences between the tree realizable distance matrix and the original distance matrix It also attempts to maximize the `entropy of betweenness-centrality' measure in the network while satisfying the distance constraints

1 citations


Journal ArticleDOI
TL;DR: The notion of a pseudo inherently ambiguous language with respect to two complexity measures is introduced and investigated and an open problem from [15] is solved in this framework.
Abstract: Contextual grammars are introduced by Solomon Marcus in 1969 based on the fundamental concept of descriptive linguistics of insertion of strings in given contexts. Internal contextual grammars are introduced by Paun and Nguyen in 1980. For contextual grammars several descriptional complexity measures and levels of ambiguity have been defined. In this paper, we analyze the trade-off between ambiguity and complexity of languages generated by internal contextual grammars. The notion of a pseudo inherently ambiguous language with respect to two complexity measures is introduced and investigated. These languages can be generated by unambiguous grammars which are minimal with respect to one measure and ambiguous if they are minimal with respect to the other measure. An open problem from [15] is solved in this framework.