Results 1  10
of
96
ProbView: A Flexible Probabilistic Database System
 ACM TRANSACTIONS ON DATABASE SYSTEMS
, 1997
"... ... In this article, we characterize, using postulates, whole classes of strategies for conjunction, disjunction, and negation, meaningful from the viewpoint of probability theory. (1) We propose a probabilistic relational data model and a generic probabilistic relational algebra that neatly capture ..."
Abstract

Cited by 202 (14 self)
 Add to MetaCart
... In this article, we characterize, using postulates, whole classes of strategies for conjunction, disjunction, and negation, meaningful from the viewpoint of probability theory. (1) We propose a probabilistic relational data model and a generic probabilistic relational algebra that neatly captures various strategies satisfying the postulates, within a single unified framework. (2) We show that as long as the chosen strategies can be computed in polynomial time, queries in the positive fragment of the probabilistic relational algebra have essentially the same data complexity as classical relational algebra. (3) We establish various containments and equivalences between algebraic expressions, similar in spirit to those in classical algebra. (4) We develop algorithms for maintaining materialized probabilistic views. (5) Based on these ideas, we have developed
Dependencies revisited for improving data quality,
, 2008
"... Abstract Dependency theory is almost as old as relational databases themselves, and has traditionally been used to improve the quality of schema, among other things. Recently there has been renewed interest in dependencies for improving the quality of data. The increasing demand for data quality te ..."
Abstract

Cited by 69 (4 self)
 Add to MetaCart
(Show Context)
Abstract Dependency theory is almost as old as relational databases themselves, and has traditionally been used to improve the quality of schema, among other things. Recently there has been renewed interest in dependencies for improving the quality of data. The increasing demand for data quality technology has also motivated revisions of classical dependencies, to capture more inconsistencies in reallife data, and to match, repair and query the inconsistent data. This paper aims to provide an overview of recent advances in revising classical dependencies for improving data quality.
Integrity control in relational database systems  an overview
 Data & Knowledge Engineering
, 1993
"... Grefen, P.W.P.J. and P.M.G. Apers, Integrity control in relational database systems An overview, Data & ..."
Abstract

Cited by 45 (3 self)
 Add to MetaCart
(Show Context)
Grefen, P.W.P.J. and P.M.G. Apers, Integrity control in relational database systems An overview, Data &
GADT: A Probability Space ADT for Representing and Querying the Physical World
 In ICDE
, 2002
"... Large sensor networks are being widely deployed for measurement, detection, and monitoring applications. Many of these applications involve database systems to store and process data from the physical world. This data has inherent measurement uncertainties that are properly represented by continuous ..."
Abstract

Cited by 36 (1 self)
 Add to MetaCart
Large sensor networks are being widely deployed for measurement, detection, and monitoring applications. Many of these applications involve database systems to store and process data from the physical world. This data has inherent measurement uncertainties that are properly represented by continuous probability distribution functions (pdf's). We introduce a new objectrelational data type, the Gaussian ADT GADT, that models physical data as gaussian pdf's, and we show that existing index structures can be used as fast access methods for GADT data. We also present a measuretheoretic model of probabilistic data and evaluate GADT in its light.
Query evaluation in probabilistic relational databases
 Theoretical Computer Science
, 1997
"... ..."
(Show Context)
Probabilistic Temporal Databases, I: Algebra
"... ... In this paper, we first introduce the syntax of TemporalProbabilistic (TP) relations and then show how they can be converted to an explicit, significantly more spaceconsuming form called Annotated Relations. We then present a Theoretical Annotated Temporal Algebra (TATA). Being explicit, TATA ..."
Abstract

Cited by 33 (7 self)
 Add to MetaCart
... In this paper, we first introduce the syntax of TemporalProbabilistic (TP) relations and then show how they can be converted to an explicit, significantly more spaceconsuming form called Annotated Relations. We then present a Theoretical Annotated Temporal Algebra (TATA). Being explicit, TATA is convenient for specifying how the algebraic operations should behave, but is impractical to use because annotated relations are overwhelmingly large. Next, we
An Introduction to the Fuzzy Set and Possibility TheoryBased Treatment of Soft Queries and Uncertain Or Imprecise Databases
, 1994
"... In this paper, it is shown that fuzzy sets and possibility theory provide an homogeneous framework for the representation of both imprecise/uncertain information and soft queries with a flexible interpretation. Incompletely known information as well as flexible query handling capabilities are expect ..."
Abstract

Cited by 30 (4 self)
 Add to MetaCart
In this paper, it is shown that fuzzy sets and possibility theory provide an homogeneous framework for the representation of both imprecise/uncertain information and soft queries with a flexible interpretation. Incompletely known information as well as flexible query handling capabilities are expected to extend the range of applications for future database management systems. The term fuzzy databases which is extensively used in the specialized literature covers several different meanings which are reviewed. A special emphasis is put on flexible queries addressed to regular databases. Such queries enables the user to easily express preferences among more or less admissible attribute values. Several approaches for introducing flexibility, including fuzzy sets, are compared. A query language based on SQL is outlined and some issues related to query processing are discussed. In addition, possibility theory proves to be useful for representing imperfectly known data and soft constraints. P...
A New Definition of Fuzzy Functional Dependency in Fuzzy Relational Databases
 International Journal of Intelligent Systems
, 1994
"... The need to incorporate and treat information given in fuzzy terms in Relational Databases has concentrated a great effort in the last years. This paper focuses on the treatment of functional dependencies (f.d.) between attributes of a relation scheme. We review other approaches to this problem and ..."
Abstract

Cited by 22 (11 self)
 Add to MetaCart
The need to incorporate and treat information given in fuzzy terms in Relational Databases has concentrated a great effort in the last years. This paper focuses on the treatment of functional dependencies (f.d.) between attributes of a relation scheme. We review other approaches to this problem and present some of its missfunctions concerning intuitive properties a fuzzy extension of f.d. should verify. Then we introduce a fuzzy extension of this concept to overcome the previous anomalous behaviors and study its properties. Of primary interest is the completeness of our fuzzy version of Armstrong axioms in order to derive all the fuzzy functional dependencies logically implied by a set of f.f.d. just using these axioms. 1 1 The Crisp Relational Model Relational Databases ([Codd 70]) constitute the main approach to the treatment of databases. It is considered a set of Attributes fA h g h=1:::n and an instance r of a relation scheme R(A 1 ; : : : ; A n ). The database contain several
A Data Model and Algebra for Probabilistic Complex Values
 Annals of Mathematics and Artificial Intelligence
, 2000
"... We present a probabilistic data model for complex values. More precisely, we introduce probabilistic complex value relations, which combine the concept of probabilistic relations with the idea of complex values in a uniform framework. We elaborate a modeltheoretic definition of probabilistic combina ..."
Abstract

Cited by 19 (2 self)
 Add to MetaCart
(Show Context)
We present a probabilistic data model for complex values. More precisely, we introduce probabilistic complex value relations, which combine the concept of probabilistic relations with the idea of complex values in a uniform framework. We elaborate a modeltheoretic definition of probabilistic combination strategies, which has a rigorous foundation on probability theory. We then define an algebra for querying database instances, which comprises the operations of selection, projection, renaming, join, Cartesian product, union, intersection, and difference. We prove that our data model and algebra for probabilistic complex values generalizes the classical relational data model and algebra. Moreover, we show that under certain assumptions, all our algebraic operations are tractable. We finally show that most of the query equivalences of classical relational algebra carry over to our algebra on probabilistic complex value relations. Hence, query optimization techniques for classical relational algebra can easily be applied to optimize queries on probabilistic complex value relations. Keywords: Complex value databases, probabilistic databases, data model, relational algebra, query languages. AMS Subject classification: Primary 68P15, 68P20; Secondary 68T30, 68T37 1.
Accommodating Imprecision in Database Systems: Issues and Solutions
 SIGMOD Record
, 1990
"... Most database systems are designed under assumptions of precision of both the data stored in their databases, and the requests to retrieve data. In reality, however, these assumptions are often invalid, and in recent years considerable attention has been given to issues of imprecision i database sys ..."
Abstract

Cited by 18 (0 self)
 Add to MetaCart
Most database systems are designed under assumptions of precision of both the data stored in their databases, and the requests to retrieve data. In reality, however, these assumptions are often invalid, and in recent years considerable attention has been given to issues of imprecision i database systems. In this paper we review the major solutions for accommodating imprecision, and we describe issues that have yet to addressed, offering possible research directions. 1 In t roduct ion Information stored in a database is precise if it is assured to be identical to the "real world" information which it represents. When precise information is unavailable, it is often the case that some relevant information is nonetheless available. In these cases, it may be advantageous to design methods by which this information, termed imprecise information, can be stored, manipulated and retrieved. Imprecision may also be present in requests to retrieve data, when users, either intentionally or by necessity, formulate their queries in imprecise terms. Depending on the data model used, the information stored in a database may take different forms, and imprecision could affect each and every one of them. For example, in the entity