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Extraction of information from unstructured or semistructured Web documents often requires a recognition and delimitation of records. (By “record” we mean a group of information relevant to some entity.) Without first chunking documents that contain multiple records according to record boundaries, extraction of record information will not likely(More)
Electronically available data on the Web is exploding at an ever increasing pace. Much of this data is unstructured, which makes searching hard and traditional database querying impossible. Many Web documents, however, contain an abundance of recognizable constants that together describe the essence of a document's content. For these kinds of data-rich,(More)
Automatically recognizing which Web documents are " of interest " for some specified application is non-trivial. As a step toward solving this problem, we propose a technique for recognizing which multiple-record Web documents apply to an ontologically specified application. Given the values and kinds of values recognized by an ontological specification in(More)
Web documents that are either partially or completely duplicated in content are easily found on the Internet these days. Not only these documents create redundant information on the Web, which take longer to filter unique information and cause additional storage space, but also they degrade the efficiency of Web information retrieval. In this paper, we(More)
Taking advantage of the popularity of the web, online marketplaces such as Ebay (.com), advertisements (ads for short) websites such as Craigslist(.org), and commercial websites such as Carmax(.com) (allow users to) post ads on a variety of products and services. Instead of browsing through numerous websites to locate ads of interest, web users would(More)
Among the HTML elements, HTML tables [RHJ98] encapsulate hierarchically structured data (hierarchical data in short) in a tabular structure. HTML tables do not come with a rigid schema and almost any forms of two-dimensional tables are acceptable according to the HTML grammar. This relaxation complicates the process of retrieving hierarchical data from HTML(More)
We give a straightforward definition for redundancy in individual nested relations and define a new normal form that precisely characterizes redundancy for nested relations. We base our definition of redundancy on an arbitrary set of functional and multivalued dependencies, and show that our definition of nested normal form generalizes standard relational(More)