H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\imath$\end{document}LεX: A System for Semantic Information Extraction from Web Documents

• Published in: Enterprise Information Systems pp. 194 - 209
• Main Authors: Ruffolo, Massimo, Manna, Marco
• Format: Book Chapter
• Language: English
• Published: Berlin, Heidelberg Springer Berlin Heidelberg 2008
• Series: Lecture Notes in Business Information Processing
• Subjects: Class Instance; Domain Ontology; Information Extraction; Regular Expression; Stock Index
• ISBN: 3540775803; 9783540775805
• ISSN: 1865-1348; 1865-1356
• DOI: 10.1007/978-3-540-77581-2_13

Recognizing and extracting meaningful information from Web unstructured documents, taking into account their semantics, is an important problem of information and knowledge management. This paper describes H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\imath$\end{document}LεX, a system implementing a novel logic-based approach to information extraction from unstructured documents. The approach adopted in the H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\imath$\end{document}LεX system is founded on a new two-dimensional representation of documents, and heavily exploits DLP +  - an extension of disjunctive logic programming for ontology representation and reasoning, which has been recently implemented on top of the DLV reasoning environment. Unlike previous systems, which are mainly syntactic, H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\imath$\end{document}LεX combines both semantic and syntactic knowledge for a powerful information extraction. Ontologies, representing the semantics of information to be extracted, are encoded in DLP + , while the extraction patterns are expressed using regular expressions and an ad hoc two-dimensional grammar. The execution of DLP +  reasoning modules, encoding the grammar expressions, yields the actual extraction of information from the input document. H\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\imath$\end{document}LεX allows the semantic information extraction from both HTML pages and flat text documents by using synthetic and very expressive extraction patterns.