1,721,054 research outputs found
Cut & Paste
No full textThe paper develops EDITOR, a language for manipulating semi-structured documents, such as the ones typically available on the Web. EDITOR programs allow to search and restructure a document. They are based on two simple ideas, taken from text editors: Search” instructions are used to select regions of interest in a document, and “cut & paste” to restructure them. We study the expressive power and the complexity of these programs. We show that they are computationally complete, in the sense that any computable document restructuring can be expressed in EDITOR. We also study the complexity of a safe subclass of programs, showing that it captures exactly the class of polynomial-time restructurings. The language has been implemented in Java, and is used in the ARANEUS project to build database views over Web sites
Cut and Paste
No full textThe paper develops Editor, a language for manipulating semistructured documents, such as those typically available on the Web. Editor programs are based on two simple ideas, taken from text editors: “search” instructions are used to select regions of interest in a document, and “cut & paste” instructions to restructure them. We study the expressive power and the complexity of these programs. We show that they are computationally complete, in the sense that any computable document restructuring can be expressed in Editor. We also study the complexity of a safe subclass of programs, showing that it captures exactly the class of polynomial-time restructurings. The language has been implemented in Java and is currently used in the project as a basis for a wrapper-generation toolkit
The LOGIDATA+ Language and Semantics
No full textA language for the LOGIDATA+ model is presented. The language is rule-based and allows for the management of complex structures, classes, hierarchies and data functions. Negation is allowed in the body of rules. The semantics is based on a fixpoint operator and represents an extension of ordinary declarative-language semantics. The main issue is the management of oid-invention, that is, the creation and manipulation of objects belonging to the classes of a scheme. In order to correctly deal with negation and multivalued data functions, an extended notion of stratification is introduced
To Weave the Web
No full textThe paper discusses the issue of views in the Web context. We introduce a set of languages for managing and restructuring data coming from the World Wide Web. We present a spe- cific data model, called the ARANEUS Data Model, inspired to the structures typically present in Web sites. The model allows us to describe the scheme of a Web hypertext, in the spirit of databases. Based on the data model, we develop two languages to support a sophisticate view definition process: the first, called ULIXES, is used to build database views of the Web, which can then be analyzed and integrated using database techniques; the sec- ond, called PENELOPE, allows the definition of derived Web hypertexts from relational views. This can be used to generate hypertextual views over the Web
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