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Identifier uch.csd.msc//1998velegrakis
Title Δηλωτικός Προσδιορισμός Μεταφραστών Z39.50 με Χρήση Περιγραφικής Λογικής
Alternative Title Declarative Specification of Z39.50 wrappers using Description Logic
Creator Velegrakis, John
Abstract Nowadays, an active topic in the area of Information Retrieval is the problem of accessing, retrieving and integrating information located in a number of physically distributed heterogeneous information sources. In such a case, in order to achieve interoperability, a usual approach is the use of a common reference data model. Over each source there should be an application which translates each query expressed in the common data model to the native language of the underlying data source. The same application is also responsible to translate the results returned from the source to the common model. Such special applications are called wrappers. Z39.50 is a protocol for accessing and retrieving heterogeneous information sources, which is the ANSI/NISO Z39.50 Standard as well as ISO 23950. It presumes a common model which consists of a flat (unstructured) list of fields called Access Points which can be used by the user to construct queries. It also specifies a common boolean query language. The topic of this thesis is the creation of a method for the declarative specification of Z39.50 wrappers. Translating the Z39.50 queries to the native language of the underlying source is a complicated process since the source may be a data base or any other repository with highly structured data. What we are trying to do is to find a method that would give the user the ability to express the mappings from the flat Z39.50 data model and query language primitive operators, to the structured source data model and query language constructors, in an expressive and efficient way. In order to achieve this, we used Description Logic. Description Logic generates concept languages which are very expressive and easy to handle since they are quite close to natural language of the user. Finally, Description Logic provides a formal framework for tackling several issues of Z39.50.
Issue date 1998-07-01
Date available 1998-11-20
Collection   School/Department--School of Sciences and Engineering--Department of Computer Science--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/d/3/7/metadata-dlib-1998velegrakis.tkl Bookmark and Share
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