Showing papers by "Grzegorz Rozenberg published in 1986"

The Book of L

Abstract: Investigations into Drosophila Wing Development - Results from a Lindenmayer Model.- Fibonacci Words - A Survey.- Planar Map Generation by Parallel Binary Fission/Fusion Grammars.- Modular Trellises.- A New Proof for the DOL Sequence Equivalence Problem and its Implications.- On Compound Lindenmayer Systems.- Graph Grammars with Application Conditions.- The ETOL Hierarchy is in the OI Hierarchy.- Polyhedral Cell Shapes.- On Cyclically Overlap-Free Words in Binary Alphabets.- The Theoretical Basis of the Transplantation Experiment.- Fixed and Stationary ?-Words and ?-Languages.- DOL Schemes and Recurrent Words.- Stochastic OL Systems and Formal Power Series.- Complexity of L-Systems.- Compartmental Hybrid State Production-Diffusion Systems with Application to Prestalk-Prespore Pattern Regulation in Cellular Slime Molds.- Hierarchical Aspects of Plant Development.- Rule Trees Represent Derivations in Edge Replacement Systems.- Languages Defined by Indian Parallel Systems.- L Systems and NLOG-Reductions.- The Parikh-Boundedness of ETOL Languages of Finite Index.- Computer Networks with Compact Routing Tables.- Unconventional Leaves.- A Uniform Model for the Growth of Biological Organisms: Cooperating Sequential Processes.- Graph Technology Applied to a Software Project.- Some Systems for Map Generation.- A Programming Language for Lindenmayer Systems.- A Note on Significance of Cellular Interaction in L-System.- EOL Grammars and Search Trees.- Variation in Inflorescence Structure in Cotoneaster Franchetti.- Partial Path Groups and Parallel Graph Contractions.- When L was Young.- Equivalence Problems for Regular Sets of Word Morphisms.- Parentheses Grammars and Lindenmayer Grammars.- Array Languages and Lindenmayer Systems - A Survey.- Symmetric Distributed Termination.- Development, Growth and Time.- On the Set of all Subgraphs of the Graphs in a Boundary NLC Graph Language.- Graph-Controlled Systems - An Extension of OL Systems.

Advances in Petri nets 1985

Abstract: The signing of a contract - a tree-structured application modelled with petri net building blocks.- Checking properties of nets using transformations.- Petri nets and algebraic calculi of processes.- Fair controls and their realization.- Beta processes of C/E systems.- Synchronic distances in C/E systems.- Process periods and system reconstruction.- Guidelines on using net analysis techniques with large specifications.- Application of an extension of petri nets to modelization of control and production processes.- Making nets abstract and structured.- Petri net tools.- Projections of CE-systems.- Synchronic structure.- Safe states in Banker like resource allocation Problems.- Coordination technology and Petri nets.- Pascal semantics by a combination of denotational semantics and high-level petri nets.- On the invariants of coloured Petri Nets.- A logical formalism for the study of the finite behaviour of Petri nets.- Determination of a poset by its co-relation.- Some equivalence notions for concurrent systems. An overview.- Towards a comprehensive office model integrating information and resources.- Non-linear invariants for coloured Petri nets with interdependent tokens application to the proof of parallel programs.- Protocol analysis using Numerical Petri Nets.- Petri nets, morphisms and compositionality.- M-timed Petri nets, priorities, preemptions, and performance evaluation of systems.

Boundary NLC graph grammars--basic definitions, normal forms, and complexity

Abstract: Node label controlled (NLC) grammars are graph grammars (operating on node labeled undirected graphs) which rewrite single nodes only and establish connections between the embedded graph and the neighbors of the rewritten node on the basis of the labels of the involved nodes only. They define (possibly infinite) languages of undirected node labeled graphs (or, if we just omit the labels, languages of unlabeled graphs). Here we consider a restriction of NLC grammars, so-called boundary NLC (BNLC) grammars , distinguished by the property that whenever in a graph already generated two nodes may be rewritten, then these nodes are not adjacent. The graph languages generated by this type of grammars are called BNLC languages . Although we show that this restriction leads to a smaller class of languages, still enough generative power remains to define interesting graph languages. For example, trees, complete bipartite graphs, maximal outerplanar graphs, k -trees, graphs of bandwidth ⩽ k , graphs of cyclic bandwidth ⩽ k , graphs of binary tree bandwidth ⩽ k , graphs of cutwidth ⩽ k (always for a fixed positive integer k ) turn out all to be BNLC languages. We prove a number of normal forms for BNLC grammars and then we indicate their usefulness by various applications. In particular, we show that for connected graphs of bounded degree the membership problem for BNLC languages is solvable in deterministic polynomial time.

Petri nets: basic notions, structure, behaviour

Abstract: We give a sketch of the theory of Petri nets. The aspects that we concentrate on are the basic notions of the theory and the interplay between the structure and behaviour of distributed systems as modelled by Petri nets. The theory we present is confined to a restricted class of Petri nets called safe Petri nets which correspond essentially to systems that have finite state spaces.

Behaviour of Elementary Net Systems

Abstract: We consider two ways of recording the behaviour of an elementary net system (EN system): via sequential observations and via non-sequential observations. In the sequential point of view each record of the behaviour of an EN system is a string of event occurrences (called a firing sequence) as registered by a sequential observer. In the nonsequential point of view we can define the behaviour of an EN system by either extracting causal order of events from firing sequences (obtaining firing traces) or by recording all nonsequential observations of event occurrences and of resulting holdings of conditions (each such record is called a process). In our contribution we discuss each of the three approaches and then relate them to each other.

Infinitary languages: basic theory and applications to concurrent systems

Abstract: The aim of this paper is to provide an outlook at this part of the theory of infinitary languages that seems to be essential for understanding the modern theory of concurrent systems. In the first part of this paper we discuss an automata-based approach to infinitary languages. In the second part we turn into applying this theory to concurrent systems as considered within the framework of Petri nets.

Graph theoretic closure properties of the family of boundary NLC graph languages

Abstract: Node label controlled (NLC) grammars are graph grammars (operating on node labeled undirected graphs) which rewrite single nodes only and establish connections between the embedded graph and the neighbors of the rewritten node on the basis of the labels of the involved nodes only. They define (possibly infinite) languages of undirected node labeled graphs (or, if we just omit the labels, languages of unlabeled graphs). Boundary NLC (BNLC) grammars are NLC grammars with the property that whenever — in a graph already generated — two nodes may be rewritten, then these nodes are not adjacent. The graph languages generated by this type of grammars are called BNLC languages.

An introduction to the NLC way of rewriting graphs

Abstract: This paper presents an introduction to the rewriting mechanism of Node-Label Controlled (NLC) graph grammars. First we present a more general framework (LEARRE graph grammars) from which NLC graph grammars are obtained through a number of restrictions. The paper is of a tutorial character with the stress on the intuitive (illustrated by examples) explanation of concepts rather than on the formalism.

Apex Graph Grammars

Abstract: Apex graph grammars are NLC-like graph grammars with the restriction that embedding edges are established between terminal nodes only. Some basic theoretical properties of these grammars are investigated.

Current Trends in Concurrency: Overviews and Tutorials

Abstract: Computer science in industry.- Dataflow and education: Data-driven and demand-driven distributed computation.- Contrasting themes in the semantics of imperative concurrency.- Functional programming and the language tale.- Design, specification and validation of hierarchies of protocols in distributed systems.- Infinitary languages: Basic theory and applications to concurrent systems.- The quest goes on: A survey of proofsystems for partial correctness of CSP.- Logic programming: The foundations, the approach and the role of concurrency.- Process theory: Semantics, specification and verification.- Applications of temporal logic to the specification and verification of reactive systems: A survey of current trends.- Petri nets: Basic notions, structure, behaviour.- Concepts for concurrent programming.

Neighborhood-uniform NLC grammars

Abstract: This paper investigates the basic properties of the class of neighborhood-uniform nodel label controlled (NUNLC) graph grammars The class of NUNLC grammars is distinguished by requiring a very natural restriction on the connection relations of NLC grammars The restriction implies “Church-Rosser property” of derivations in an NUNLC grammar, which makes the class of NUNLC grammars “technically easier” to investigate A number of combinatorial properties of the languages generated by the class of NUNLC grammars are proved Also, it is demonstrated that a number of basic properties are decidable for the class of NUNLC grammars—many of them are undecidable in the whole class of NLC grammars

An easy proof of Greibach normal form

Abstract: We present an algorithm which given an arbitrary A-free context-free grammar produces an equivalent context-free grammar in 2 Greibach normal form. The upper bound on the size of the resulting grammar in terms of the size of the initially given grammar is given. Our algorithm consists of an elementary construction, while the upper bound on the size of the resulting grammar is not bigger than the bounds known for other algorithms for converting context-free grammars into equivalent context-free grammars in Greibach normal form.

Basic notions of actor grammars

Abstract: Actor systems are a model of massively parallel systems based on asynchronous message passing. This paper presents a formalism for actor systems in the framework of graph grammars. To this aim actor grammars are introduced, motivated, and illustrated by examples. Some of the basic properties pertinent to derivations in actor grammars are discussed.

When L was Young

Abstract: Instead of a technical paper, the editors of this book want to celebrate Aristid’s birthday in a very informal way: by personal recollections from the early days of L systems. Our contribution is intended to be very non-scientific. Neither interviews nor library studies were made. The presented material results from several extended Salosauna sessions. We are completely aware of the fact that several important details are missing, e.g., the story of Gabor Herman getting involved. In spite of eventual inaccuracies, we still hope that our contribution will be of interest for both the L and the non-L crowd.

Restricting the complexity of regular DNLC languages

Abstract: Regular directed node-label controlled graph grammars (RDNLC grammars) originated from the need for a formal description of event structure languages (related to Petri nets) and of dependence graph languages (related to trace languages). In this framework complexity problems concerning event structure languages and dependence graph languages can be reduced to complexity problems concerning RDNLC languages.

Fundamentals of edge-label controlled graph grammars

Abstract: We introduce a graph-grammar model based on edge-replacement, where both the rewriting and the embedding mechanisms are controlled by edge labels. The general power of this model is established — it turns out to have the complete power of recursive enumerability (in a sense to be made precise in the paper). In order to understand where this power originates, we identify three basic features of the embedding mechanism and examine how restrictions on these features affect the generative power. In particular, by imposing restrictions on all three features simultaneously, we obtain a graph-grammar model that was previously introduced by Kreowski and Habel.

Coordinated pair systems ; part II : sparse structure of Dyck words and Ogden's lemma

Abstract: In this paper we continue the investigation of the structure of computations in cp Systems which was initiated in Part I of this paper. Hère again our main combinatorial tooi is the structure of Dyck words {and the Exchange Theorem). However in this paper we investigate the \"sparse structure\" of Dyck words (Le., the structure of sparse subworks of Dyck words) and use our results about this sparse structure to dérive Ogden's pumping lemma for context-free languages. Résumé. Dans cet article, nous poursuivons V'étude de la structure des calculs dans les systèmes cp, étude commencée dans la première partie de cet article. A nouveau, notre outil combinatoire principal est la structure des mots de Dyck (et le théorème d'échange). Ici, nous étudions la « structure dispersée » des mots de Dyck (L e. la structure de sous-mots fractionnés de mots de Dyck) et nous employons nos résultats sur cette structure pour obtenir le lemme d'itération d'Ogden pour les langages algébriques.

Coordinated pair systems ; part I : Dyck works and classical pumping

Abstract: The notion of a coordinated pair system, cp system for short, is a special instance of an ects System which in turn provides a common framework for quite a number of grammar and machine models encountered in the literature. In particular, the notion of a cp System corresponds very closely to (is another formulation of ) the notion of a push-down automaton. In this paper we continue the investigation of cp Systems and in particular we investigate the possibility of obtaining pumping properties of context-free languages via the analysis of computations in cp Systems. In order to do this we analyze the combinatorial structure of Dyck words. The properties of Dyck words we investigate stem from the combinatorial analysis of computations in cp Systems. We demonstrate how this correspondence can be used for proving the classical pumping lemma. Résumé. La notion de système de paires coordonné, abrégé en cp système, est un cas particulier de ects système qui, lui, fournit un cadre commun à un grand nombre de modèles de grammaires et de machines rencontrés dans la littérature. En particulier, la notion de cp système est très proche (est une autre formulation) de celle d'automate à pile. Dans cet article, nous continuons l'étude des cp systèmes, et nous étudions en particulier la possibilité d'obtenir des propriétés d'itération de langages algébriques à travers l'analyse des calculs dans les cp systèmes. Pour ce faire, nous analysons la structure combinatoire des mots de Dyck. Les propriétés des mots de Dyck que nous étudions proviennent d'une analyse combinatoire des calculs dans les cp systèmes. Nous montrons comment cette correspondance peut seqskèù démontrer le lemme d'itération classique.

Direction independent context-sensitive grammars

Abstract: A direction independent variant of the standard normal form for context-sensitive grammars is given: the context-free productions are of the form A → a or A → BC and the context-sensitive productions are of the form AB → AC or BA → CA , where AB → AC is a production if and only if BA → CA is a production. The equivalence of these grammars with the context-sensitive grammars is proved.