143 resultados para grammars
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This paper proposes to reflect from a semiotic perspective on the transformation that brands have undergone since the rise of the Internet. After a brief theoretical introduction to digital communication and the semiotics of brands, the case of the Google brand is analyzed by applying concepts of generative and interpretive semiotics. The paper holds that the iconic and linguistic enunciations are secondary with respect to interaction. In digital media interaction — the interactive experience that the Internet user lives — is a fundamental component of the hypermedia cocktail and occupies a central position in the brand building process. The article concludes with some of the questions and special characteristics raised by so-called eBranding.
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This thesis introduces an extension of Chomsky’s context-free grammars equipped with operators for referring to left and right contexts of strings.The new model is called grammar with contexts. The semantics of these grammars are given in two equivalent ways — by language equations and by logical deduction, where a grammar is understood as a logic for the recursive definition of syntax. The motivation for grammars with contexts comes from an extensive example that completely defines the syntax and static semantics of a simple typed programming language. Grammars with contexts maintain most important practical properties of context-free grammars, including a variant of the Chomsky normal form. For grammars with one-sided contexts (that is, either left or right), there is a cubic-time tabular parsing algorithm, applicable to an arbitrary grammar. The time complexity of this algorithm can be improved to quadratic,provided that the grammar is unambiguous, that is, it only allows one parsefor every string it defines. A tabular parsing algorithm for grammars withtwo-sided contexts has fourth power time complexity. For these grammarsthere is a recognition algorithm that uses a linear amount of space. For certain subclasses of grammars with contexts there are low-degree polynomial parsing algorithms. One of them is an extension of the classical recursive descent for context-free grammars; the version for grammars with contexts still works in linear time like its prototype. Another algorithm, with time complexity varying from linear to cubic depending on the particular grammar, adapts deterministic LR parsing to the new model. If all context operators in a grammar define regular languages, then such a grammar can be transformed to an equivalent grammar without context operators at all. This allows one to represent the syntax of languages in a more succinct way by utilizing context specifications. Linear grammars with contexts turned out to be non-trivial already over a one-letter alphabet. This fact leads to some undecidability results for this family of grammars
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We study several extensions of the notion of alternation from context-free grammars to context-sensitive and arbitrary phrase-structure grammars. Thereby new grammatical characterizations are obtained for the class of languages that are accepted by alternating pushdown automata.
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This article brings to light an important variable involved in explaining a type of competence divergence in an instance of bilingual acquisition: heritage speaker (HS) bilingualism. We present results of experiments with European Portuguese (EP) heritage speakers (HSs), showing that they have full morpho-syntactic and semantic competence of inflected infinitives, similar to EP monolinguals. We show this constitutes clear evidence of competence mismatches between heritage speakers of European and Brazilian Portuguese, comparing our results to Rothman’s (2007) experimental evidence that Brazilian Portuguese (BP) heritage speakers lack knowledge of inflected infinitives. These comparative results are especially relevant because inflected infinitives were argued (Pires, 2002, 2006) to have been lost in colloquial BP dialects, although educated monolinguals demonstrate target competence.
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Programa de doctorado: Estudios interdisciplinares de Lengua, Literatura, Cultura, Traducción y Tradición Clásica
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Grammars for programming languages are traditionally specified statically. They are hard to compose and reuse due to ambiguities that inevitably arise. PetitParser combines ideas from scannerless parsing, parser combinators, parsing expression grammars and packrat parsers to model grammars and parsers as objects that can be reconfigured dynamically. Through examples and benchmarks we demonstrate that dynamic grammars are not only flexible but highly practical.
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Mode of access: Internet.
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"UIUCDCS-R-74-624"
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"UIUCDCS-R-74-625"
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Bibliography: p. 67.
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"Supported in part by the Dept. of Computer Science, University of Illinois ... and in part by the Advanced Research Projects Agency ... under Contract no. U.S. AF 30(602)4144."