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Showing papers by "Grzegorz Rozenberg published in 1980"


Book
01 Mar 1980

870 citations


Book
01 Jan 1980
TL;DR: A survey of the different areas of the theory of developmental systems and languages in such a way that it discusses typical results obtained in each particular problem area.
Abstract: The paper gives a survey of the different areas of the theory of developmental systems and languages. It is organized in such a way that it discusses typical results obtained in each particular problem area. The results quoted may not always be the most important ones but they are quite representative for the direction of research in this theory. Proofs are not given and, consequently, the basic techniques for solving problems in this theory are not discussed. An attempt has been made to cover also the most recent results. Most of the results have not yet appeared in print. To appear in J. Tou (ed. ), Advances in Information Systems Science, Plenum Press.

771 citations


Journal ArticleDOI
TL;DR: A relationship between parallel rewriting systems and two-way machines is investigated, finding restrictions on the “copying power” of these devices endow them with rich structuring and give insight into the issues of determinism, parallelism, and copying.

181 citations


Journal ArticleDOI
TL;DR: The main theorem is a result on the combinatorial structure of graph languages generated by NLC grammars; it resembles the pumping theorem for context-free string languages.

163 citations


Journal ArticleDOI
TL;DR: Very simple languages are introduced which play the same role for the class of recursively enumerable languages that the Dyck languages play for theclass of context-free languages.
Abstract: Fixed point languages and equality languages of homomorphisms and dgsm mappings are consid- ered. Some basic properties of these classes of languages are proved, and it is shown how to use them to represent recursively enumerable sets. In particular, very simple languages are introduced which play the same role for the class of recursively enumerable languages that the Dyck languages play for the class of context-free languages. Finally, a new type of acceptor for defining equality languages is introduced. KEY WOADS AND PHRASES: equality language, fLxed point language, recursively enumerable language, determin- istic sequential machine, Turing machine, Post correspondence problem, shuffle, AFL generator, representation of languages

93 citations


Journal ArticleDOI
TL;DR: Three topics are investigated quite thoroughly: (1) the role of the connection relation in an NLC grammar, (2) “context-freeness” of NLC grammars, and (3) the ability of N LC grammARS to generate string languages.

85 citations


Journal ArticleDOI
TL;DR: This paper study systematically three basic classes of grammars incorporating parallel rewriting: Indian parallel Grammars, Russian parallel grammARS and L systems, and introduces new classes of rewriting systems ( ETOL [ k ] systems, ETOLIP systems and ETOLRP systems).
Abstract: In this paper we study systematically three basic classes of grammars incorporating parallel rewriting: Indian parallel grammars, Russian parallel grammars and L systems. In particular by extracting basic characteristics of these systems and combining them we introduce new classes of rewriting systems ( ETOL [ k ] systems, ETOLIP systems and ETOLRP systems) Among others, some results on the combinatorial structure of Indian parallel languages and on the combinatorial structures of the new classes of languages are proved. As far as ETOL systems are concerned we prove that every ETOL language can be generated with a fixed (equal to 8) bounded degree of parallelism.

29 citations


Journal ArticleDOI
TL;DR: An explicit bound is given for a solution of the D O L sequence equivalence problem such that the sequences generated by G 1 and G 2 are equal if and only if the corresponding first C elements of the sequences are equal.

16 citations


Journal ArticleDOI
TL;DR: The notion of a universal grammar is investigated in this framework, demonstrating the existence of selection universal grammars under weak conditions on the selection family.
Abstract: Selective substitution grammars first introduced by Rozenberg are further investigated In particular we study `context-free grammars' with selection, since the original model is too general in its generative power It is shown how the families of context-free, EOL and ETOL languages can be characterized by selective context-free grammars Further the effect of linguistic restrictions on the family of selection languages is investigated Finally, the notion of a universal grammar is investigated in this framework, demonstrating the existence of selection universal grammars under weak conditions on the selection family

15 citations


Book
01 Jan 1980
TL;DR: A criminal network is a social network, but it is also a flexible order as mentioned in this paper, and centrality and key players in a criminal network are central targets of a police investigation.
Abstract: Acknowledgements Chapter 1: The Criminal Network Perspective 1 A Criminal Network is a Social Network, but 2 Flexible Order 3 Centrality and Key Player Designations Direct Centrality and Visibility Brokers as Key Players 4 Seek, Rather than Assume, Structure Organization of the Book Chapter 2: Case Study Sources and Designs 1 Case Selection and Access 2 Case Study Descriptions Krebs' Terrorist Network Project Ciel Project Caviar Projects Siren and Togo Operation Springtime 2001 Street Gangs and Drug Distribution in Montreal North 3 Designing the Criminal Networks The Matrix and the Sociogram Assembling the Final Network Representation 4 Centrality and Analogous Network Measures In the Thick of Things In Between In the Thick of the Thick Less Efficiently In Between Localized Clustering 5 Challenges in Criminal Network Analysis Clarity and Attributes in Relational Data Missing Data Beyond the Final Network Representation Missing Data Within the Final Network Representation Are Central Participants Simply Central Targets of a Police Investigation? Are Law-enforcement Intercepted Networks Simply Failed Criminal Networks? Chapter 3: Partnership Configurations in Illegal DrugImportation 1 Resource-Sharing in Crime 2 Two Networks in One 3 Direct and Indirect Connectivity Within the Ciel Network 4 Conclusion Chapter 4: The Efficiency-Security Trade-off 1 The Network's Objective and Time-to-Task 2 Snakes and Clusters 3 Centrality Issues and Distinctions 4 Conclusion Chapter 5: Legitimate Strengths in Criminal Networks 1 Legitimate Actors in Criminal Settings 2 Differences Between Trafficker and Non-Trafficker Subsets 3 Seeds in the Network 4 The Direction of Contact 5 Discrete Participants and Pawns 6 Conclusion Chapter 6: Law-Enforcement Disruption of a Drug Importation Network 1 Coding for Criminal Network Dynamics The Context of Control The Uniqueness of the Caviar Case 2 Characteristics of the Overall Caviar Network 3 Changes in the Caviar Network Across Investigative Phases Decentralization and Core Changes Disorder and Accountability 4 Conclusion Chapter 7: Brokerage Qualifications in Ringing Scripts 1 Crime Scripts and Flexibility 2 Merging Crime Script and Social Network Frameworks 3 The Case Study Design Determining Brokerage Qualifications Assessing Participant Removal Impact on Script Permutation 4 Criminal Network Flexibility and Script Permutation Overall Scripts

14 citations


Book ChapterDOI
01 Jan 1980
TL;DR: The theory of L systems has a great impact on formal language theory as discussed by the authors and has enriched the theory of formal languages and also been able to put the theory in a totally new perspective.
Abstract: Publisher Summary L systems were originated by Aristid Lindenmayer in connection with biological considerations in 1968. The theory of L systems has a great impact on formal language theory. Two main features of the theory of L systems are parallelism in the rewriting process and the notion of a grammar conceived as a description of a dynamic process, rather than of a static one. L systems have enriched the theory of formal languages and also been able to put the theory in a totally new perspective. This chapter discusses the mathematical theory of L systems. One of the outstanding features of the theory of L systems is that its core fits into a systematic and basic mathematical framework formed by single or several iterated homomorphisms or finite substitutions on a free monoid. The chapter discusses this systematic framework. The basic construct of L systems theory is the daily oral language (DOL) system. A DOL system represents a basic mathematical structure—the iteration of a single homomorphism on a free monoid. Although mathematically most simple, DOL systems give a clear insight into the essential ideas and techniques behind L systems and parallel rewriting in general.

Journal ArticleDOI
TL;DR: A new type of grammar called a DOS system is introduced and investigated, which formalizes the notion of a context free grammar without variables that is generatively deterministic.
Abstract: A new type of grammar called a DOS system is introduced and investigated. Essentially it formalizes the notion of a context free grammar without variables that is generatively deterministic.

Journal ArticleDOI
TL;DR: The notion of a DOS system is introduced which is a ‘sequential counterpart of the idea of a DOL system l’ and it is proved that the emptiness of the intersection problem for two DOS systems is proved.

Journal ArticleDOI
TL;DR: It is proved that every two equivalent D0L systems have a regular true envelope and this is an open problem and can be solved by extending some proof techniques from [2] and [3].




01 Jan 1980
TL;DR: In this paper, a general mathematical framework to deal with decidability status of derivations in E0L systems (forms) is developed based on the theory of well-quasi-orders.
Abstract: Abstract A general mathematical framework to deal with (the decidability status of) properties of derivations in E0L systems (forms) is developed. It is based on the theory of well-quasi-orders. This paper (the first of two parts) deals with the mathematical theory of the proposed approach.


Journal ArticleDOI
TL;DR: A contribution to the analysis of generative power of simple E OL forms is presented by establishing easily decidable necessary and sufficient conditions for simple EOL forms to generate (under uniform interpretations) CF languages only.
Abstract: In this paper we consider simple EOL forms (forms with a single terminal and single nonterminal) under uniform interpretations. We present a contribution to the analysis of generative power of simple EOL forms by establishing easily decidable necessary and sufficient conditions for simple EOL forms to generate (under uniform interpretations) CF languages only.

Journal ArticleDOI
TL;DR: It is shown that it is decidable whether or not two arbitrary 0S systems generate the same set of (derivation) sequences, and it is obtained as a corollary that two arbitrary context-free grammars have the same sets of derivation sequences.
Abstract: 0S systems generalize context-free grammars without nontermmals it is shown that it is decidable whether or not two arbitrary 0S systems generate the same set of (derivation) sequences It is obtained as a corollary that it is decidable whether or not two arbitrary context-free grammars have the same sets of derivation sequences

Journal ArticleDOI
TL;DR: Some basic properties of synchronized and desynchronized E0L forms are investigated and several open problems concerning those forms (and their connection to grammar forms) are solved.

Journal ArticleDOI
TL;DR: It is shown that if an E0L language has the negative prefix property and is E OL-unambiguous, then K+ is also EOL- unambiguous and several conjectures concerning ambiguity of EOL languages are disproved.



Journal ArticleDOI
TL;DR: This paper presents a systematic study of the phenomenon of synchronization in E0L systems by abstracting various essential features of derivations in those systems the notions of a coordinated and a desynchronized E0l system are formulated and properties of the classes of languages they generate studied.
Abstract: This paper presents a systematic study of the phenomenon of synchronization in E0L systems. By abstracting various essential features of derivations in those systems the notions of a coordinated E0L system and a desynchronized E0L system are formulated and properties of the classes of languages they generate studied.