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A Probabilistic Relational Algebra for the Integration of Information Retrieval and Database Systems
 ACM Transactions on Information Systems
, 1994
"... We present a probabilistic relational algebra (PRA) which is a generalization of standard relational algebra. Here tuples are assigned probabilistic weights giving the probability that a tuple belongs to a relation. Based on intensional semantics, the tuple weights of the result of a PRA expression ..."
Abstract

Cited by 173 (30 self)
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We present a probabilistic relational algebra (PRA) which is a generalization of standard relational algebra. Here tuples are assigned probabilistic weights giving the probability that a tuple belongs to a relation. Based on intensional semantics, the tuple weights of the result of a PRA expression always confirm to the underlying probabilistic model. We also show for which expressions extensional semantics yields the same results. Furthermore, we discuss complexity issues and indicate possibilities for optimization. With regard to databases, the approach allows for representing imprecise attribute values, whereas for information retrieval, probabilistic document indexing and probabilistic search term weighting can be modelled. As an important extension, we introduce the concept of vague predicates which yields a probabilistic weight instead of a Boolean value, thus allowing for queries with vague selection conditions. So PRA implements uncertainty and vagueness in combination with the...
A Prototype for Integrating Probabilistic Fact and Text Retrieval
 Proc. ISI '91, Wissensbasierte Informationssysteme und Informationsmanagement (Killenberg, H.; Kuhlen, R.; Manecke, H.J., Ed.), Konstanz, Universit ��tsverlag
, 1991
"... We describe a prototype for an information system that integrates text and fact retrieval. A query is a set of conditions which relate either to the text or the attribute values of a database object. Conditions may be assigned weights w.r.t. the query as well as to an object. These weights form the ..."
Abstract

Cited by 1 (0 self)
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We describe a prototype for an information system that integrates text and fact retrieval. A query is a set of conditions which relate either to the text or the attribute values of a database object. Conditions may be assigned weights w.r.t. the query as well as to an object. These weights form the basis for a ranking of the database objects w.r.t. the query. As user interface, the system provides a menuoriented browser.