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Output String Languages of Compositions of Deterministic Macro Tree Transducers
 Leiden University
, 2001
"... The composition of total deterministic macro tree transducers gives rise to a proper hierarchy with respect to their output string languages (these are the languages obtained by taking the yields of the output trees). There is a language not in this hierarchy which can be generated by a (quite restr ..."
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Cited by 7 (5 self)
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The composition of total deterministic macro tree transducers gives rise to a proper hierarchy with respect to their output string languages (these are the languages obtained by taking the yields of the output trees). There is a language not in this hierarchy which can be generated by a (quite restricted) nondeterministic string transducer, namely, a twoway generalized sequential machine. Similar results hold for attributed tree transducers, for controlled EDT0L systems, and for YIELD mappings (which proves properness of the IOhierarchy). Witnesses for the properness of the macro tree transducer hierarchy can already be found in the latter three hierarchies.
Resistance is Futile; Formal Linguistic Observations on Design Patterns
, 1997
"... Inspection of the current literature on Design Patterns shows that the Prime Directive for this community is Pragmatics. It hardly matters what patterns are, or how Patterns are represented formally or syntactically. What does matter is their role in enhancing the reuse of good solutions to recurrin ..."
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Cited by 5 (0 self)
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Inspection of the current literature on Design Patterns shows that the Prime Directive for this community is Pragmatics. It hardly matters what patterns are, or how Patterns are represented formally or syntactically. What does matter is their role in enhancing the reuse of good solutions to recurring problems. In this article I want to show that minimal assumptions about the pragmatic use of Patterns suffice to show that Design Patterns form just another formal language, which can be shown to be at least Recursively enumerable. Whether the language is Recursive depends on further conditions on the actual relation which is assumed to hold between a pattern and its possible invocations. There are no a priori reasons enforcing that this should be an easily decidable relation; quite to the contrary: a little amount of linguistic expressivity suffices for showing that this relation is likely to be complex. Without restrictions on the linguistic tools allowed for expressing design patterns t...
Nondeterminism, Fairness and a Fundamental Analogy
"... In this note we propose a model for unbounded nondeterministic computation which provides a very natural basis for the structural analogy between recursive function theory and computational complexity theory: P : NP ¸ = REC : RE At the same time this model presents an alternative version of the ha ..."
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In this note we propose a model for unbounded nondeterministic computation which provides a very natural basis for the structural analogy between recursive function theory and computational complexity theory: P : NP ¸ = REC : RE At the same time this model presents an alternative version of the halting problem which has been known for a decade to be highly intractable. 1 Introduction Structural complexity theory is often presented as the theory in which the results obtained for classes of languages recognized by Turing machines are transferred to a resource bounded setting. Notions like reduction, simplicity, immunity, the arithmetical hierarchy, relativizations etc. were all first defined in recursive function theory and later (relativizations of) these notions were introduced in complexity theory. All of this work was inspired by the frustration originating from the difficulty of the fundamental problem in computational complexity theory which has become known as the P ? = NP pr...
Models of Tree Translation
"... This first chapter gives an introduction into the area of tree transducer theory, and describes the results presented in Chapters 2–6. The first section addresses general issues like translations, trees, and tree grammars. Section 2 is concerned with the different models of tree transducers that ar ..."
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Cited by 4 (1 self)
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This first chapter gives an introduction into the area of tree transducer theory, and describes the results presented in Chapters 2–6. The first section addresses general issues like translations, trees, and tree grammars. Section 2 is concerned with the different models of tree transducers that are considered in the thesis. It describes the typical problems that appear in tree transducer theory, and mentions important properties of the different tree transducer models. Section 3 describes the results of
Hierarchies of String Languages Generated by Deterministic Tree Transducers
 in ‘‘Proceedings of the 5th International Conference on Developments in Language Theory–DLT’2001,’’ Lecture Notes in Computer Science
"... The composition of total deterministic macro tree transducers gives rise to a proper hierarchy with respect to the generated string languages (these are the languages obtained by taking the yields of the output trees). The same holds for attributed tree transducers, for controlled EDT0L systems, and ..."
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Cited by 1 (0 self)
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The composition of total deterministic macro tree transducers gives rise to a proper hierarchy with respect to the generated string languages (these are the languages obtained by taking the yields of the output trees). The same holds for attributed tree transducers, for controlled EDT0L systems, and for YIELD mappings (which shows properness of the IOhierarchy).
Cooperating Distributed Hyperedge Replacement Grammars
 Silesian University
, 1998
"... . The concept of cooperation and distribution as known from the area of grammar systems is introduced to graph grammars; more precisely, to hyperedge replacement (for short, HR) grammars. This can be seen as a modest approach to controlled HR. Two different derivation modes are considered, the so ca ..."
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Cited by 1 (1 self)
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. The concept of cooperation and distribution as known from the area of grammar systems is introduced to graph grammars; more precisely, to hyperedge replacement (for short, HR) grammars. This can be seen as a modest approach to controlled HR. Two different derivation modes are considered, the so called tmode and the =kmode. For the tmode it is shown that the class of hypergraph languages obtained is equal to the class of ET0L HR languages which is a natural generalization of the class of ET0L languages to hypergraphs. Keywords: graph grammar, grammar system, Lsystem 1. Introduction Cooperating grammar systems were introduced by Meersman and Rozenberg already in (Meersman and Rozenberg, 1978) in the context of twolevel grammars. The systematic study of cooperating distributed (for short, CD) grammar systems was initiated by (CsuhajVarj'u and Dassow, 1990). Since then it has become a vivid field in computer science (see, e.g., (CsuhajVarj'u et al., 1994; Paun, 1995; Paun, 1998)...
Automata and Formal Languages
, 2003
"... This article provides an introduction to the theory of automata and formal languages. The elements are presented in a historical perspective and the links with other areas are underlined. In particular, applications of the field to linguistics, software design, text processing, computational alg ..."
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This article provides an introduction to the theory of automata and formal languages. The elements are presented in a historical perspective and the links with other areas are underlined. In particular, applications of the field to linguistics, software design, text processing, computational algebra or computational biology are given.