Monadic datalog and the expressive power of languages for Web information extraction.

Research on information extraction from Web pages (wrapping) has seen much activity recently (particularly systems implementations), but little work has been done on formally studying the expressiveness of the formalisms proposed or on the theoretical foundations of wrapping. In this paper, we first...

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Publicat a:	Journal of the ACM 51, 1 (2004).
Autor principal:	Gottlob, Georg
Format:	Article
Idioma:	English
Matèries:	Theory of computation. Computation by abstract devices. Models of computation. Automata (e.g., finite, push-down, resource-bounded). Mathematical logic and formal languages. Mathematical logic. Computational logic. Formal languages. Classes defined by grammars or automata (e.g., context-free languages, regular sets, recursive sets). Information systems. Database management. Languages. Theory.