Complexity and modeling power of insertion-deletion systems

SISTEMAS DE INSERCIÓN Y BORRADO: COMPLEJIDAD Y CAPACIDAD DE MODELADO El objetivo central de la tesis es el estudio de los sistemas de inserción y borrado y su capacidad computacional. Más concretamente, estudiamos algunos modelos de generación de lenguaje que usan operaciones de reescritura de dos cadenas. También consideramos una variante distribuida de los sistemas de inserción y borrado en el sentido de que las reglas se separan entre un número finito de nodos de un grafo. Estos sistemas se denominan sistemas controlados mediante grafo, y aparecen en muchas áreas de la Informática, jugando un papel muy importante en los lenguajes formales, la lingüística y la bio-informática. Estudiamos la decidibilidad/ universalidad de nuestros modelos mediante la variación de los parámetros de tamaño del vector. Concretamente, damos respuesta a la cuestión más importante concerniente a la expresividad de la capacidad computacional: si nuestro modelo es equivalente a una máquina de Turing o no. Abordamos sistemáticamente las cuestiones sobre los tamaños mínimos de los sistemas con y sin control de grafo.COMPLEXITY AND MODELING POWER OF INSERTION-DELETION SYSTEMS The central object of the thesis are insertion-deletion systems and their computational power. More specifically, we study language generating models that use two string rewriting operations: contextual insertion and contextual deletion, and their extensions. We also consider a distributed variant of insertion-deletion systems in the sense that rules are separated among a finite number of nodes of a graph. Such systems are refereed as graph-controlled systems. These systems appear in many areas of Computer Science and they play an important role in formal languages, linguistics, and bio-informatics. We vary the parameters of the vector of size of insertion-deletion systems and we study decidability/universality of obtained models. More precisely, we answer the most important questions regarding the expressiveness of the computational model: whether our model is Turing equivalent or not. We systematically approach the questions about the minimal sizes of the insertiondeletion systems with and without the graph-control

Workshop on Formal Languages, Automata and Petri Nets

This report contains abstracts of the lectures presented at the workshop 'Formal Languages, Automata and Petri-Nets' held at the University of Stuttgart on January 16-17, 1998. The workshop brought together partners of the German-Hungarian project No. 233.6, Forschungszentrum Karlsruhe, Germany, and No. D/102, TeT Foundation, Budapest, Hungary. It provided an opportunity to present work supported by this project as well as related topics

Separating NC along the δ axis

AbstractThe “δ axis” consists of certain classes Nk such that uniform NC=⋃kNk. A diagonalization is used to prove that Nk≠Nk+1 for all k⩾0. This separation of NC along the δ axis does not imply NCk≠NCk+1, because the relationship between NCk and Nk is not known. However, it is argued that the δ axis provides a natural subdivision of NC. To support this, a careful analogy with the classes DTIME(nk) is made, illuminating a surprisingly close relationship between PTIME and NC. The definition of Nk uses ramified constructs related to a combination of parallel time and space

12th International Workshop on Termination (WST 2012) : WST 2012, February 19–23, 2012, Obergurgl, Austria / ed. by Georg Moser

This volume contains the proceedings of the 12th International Workshop on Termination (WST 2012), to be held February 19–23, 2012 in Obergurgl, Austria. The goal of the Workshop on Termination is to be a venue for presentation and discussion of all topics in and around termination. In this way, the workshop tries to bridge the gaps between different communities interested and active in research in and around termination. The 12th International Workshop on Termination in Obergurgl continues the successful workshops held in St. Andrews (1993), La Bresse (1995), Ede (1997), Dagstuhl (1999), Utrecht (2001), Valencia (2003), Aachen (2004), Seattle (2006), Paris (2007), Leipzig (2009), and Edinburgh (2010). The 12th International Workshop on Termination did welcome contributions on all aspects of termination and complexity analysis. Contributions from the imperative, constraint, functional, and logic programming communities, and papers investigating applications of complexity or termination (for example in program transformation or theorem proving) were particularly welcome. We did receive 18 submissions which all were accepted. Each paper was assigned two reviewers. In addition to these 18 contributed talks, WST 2012, hosts three invited talks by Alexander Krauss, Martin Hofmann, and Fausto Spoto

On Object Oriented Nondeterministic Supervisory Control

Implementation of complex discrete event fabrication processes can be considerably simplified by use of general reusable software modules representing the physical components. At the same time, construction of the control system can be facilitated by applying the supervisory control theory for the automatic generation of control laws. These two aspects can be joined into a general concept with object-oriented modeling and control law synthesis as foundations. The goal is to allow an operator to specify operation lists describing the required sequences of operations for the manufacturing of the product, independently of constraints given by a specific plant. With a suitable model of the capabilities and constraints of the resources of that plant, a product route can be automatically generated from the operation list. Such a product route describes all available paths through the system, for each type of product, irrespective of any other type of product that may be simultaneously present within the production system. Given a set of product routes and a model of the plant, control laws guaranteeing production according to those product specifications can be synthesized. Based on the supervisory control theory, using interleaved product routes as specification, we show how such control laws can be synthesized. An added complexity is that the specification becomes non-deterministic, in the sense that the same string of events can lead to different system states. We show that the supervisory control theory can be used with non-deterministic specifications assuming certain properties. An algorithm for synthesis of a non-deterministic supervisor is presented. We also describe an object-oriented modeling approach to discrete event fabrication processes. It is shown that the properties that have been defined as necessary for the non-deterministic supervisory approach are immediate by the modeling approach. Thus, we show that the approach to non-deterministic supervisory control can be combined with object-oriented modeling techniques, and so we have a powerful framework for implementing control of large and complex discrete event fabrication processes