Null Values Revisited in Prospect of Data Integration

  title={Null Values Revisited in Prospect of Data Integration},
  author={Guy De Tr{\'e} and Rita M. M. De Caluwe and Henri Prade},
A considerable part of the information available in the real world is inherently imperfect and/or incomplete. Traditionally, the most commonly adopted modelling approaches for dealing with imperfect and missing information are based on the use of default values and of null values. However, in order to deal with imperfect information in a more efficient way, a database system needs some more advanced modelling facilities that better reflect the semantics of the data. Such facilities become even… Expand
Making Large Information Sources Better Accessible Using Fuzzy Set Theory
The rationales behind the research of the Database, Document and Content Management group at Ghent University suggest that fuzzy set theory and its related possibility theory offer an excellent mathematical basis for the development of advanced data access methods. Expand
Qualitative Possibility Theory in Information Processing
This chapter provides a general overview of advances made in qualitative possibility theory and its application to information processing in the last decade and focuses on the ability of possibility theory to handle positive and negative information in a bipolar way. Expand
Fuzzy temporal information treatment in relational databases
Tesis Univ. Granada. Programa de doctorado. Tecnologias de la Informacion y la Comunicacion
Watching the clock for 25 years in FlyClockbase: Variability in circadian clocks of Drosophila melanogaster as uncovered by biological model curation
FlyClockbase is designed to simplify data-access for biologists and modelers and curated over 400 time series observed in wildtype fruit flies from 25 years of research on clocks, finding differences in peak time variance of the clock-proteins ‘PERIOD’ and ‘TIMELESS’, which probably stem from differences in phosphorylation-network complexity. Expand


Missing information (applicable and inapplicable) in relational databases
The purpose of this paper is to clarify and extend the treatment ofMissing information by the relational model, and places heavy emphasis on the semantic aspects of missing information. Expand
Extending the database relational model to capture more meaning
  • E. Codd
  • Computer Science
  • ACM Trans. Database Syst.
  • 1979
This paper proposes extensions to the relational model to support certain atomic and molecular semantics, a synthesis of many ideas from the published work in semantic modeling plus the introduction of new rules for insertion, update, and deletion, as well as new algebraic operators. Expand
Fuzzy And Uncertain Object-Oriented Databases: Concepts And Models
The book presents the latest research results in dealing with fuzziness and uncertainty in object-oriented databases and proves that the object- oriented paradigm lends itself extremely well to it. Expand
Generalizing Database Relational Algebra for the Treatment of Incomplete/Uncertain Information and Vague Queries
This approach, which enables a very general treatment of relational databases with fuzzy attribute values, makes an extensive use of dual possibility and necessity measures. Expand
A Formal Approach to Null Values in Database Relations
  • J. Biskup
  • Mathematics, Computer Science
  • Advances in Data Base Theory
  • 1979
The view that tuples denote statements of predicate logic about database relations is adopted, which means that a null value of the first kind and the second kind corresponds to an existentially quantified variable, respectively universally quantified variables. Expand
A Formalization of ODMG Queries
This paper presents a formalization of the ODMG model and the OQL query language that is used in the CROQUE project as a basis for query optimization. Expand
More commentary on missing information in relational databases (applicable and inapplicable information)
The purpose of this paper is to respond to comments and proposed changes received, while continuing to place heavy emphasis on the semantic aspects of missing information. Expand
Extended possibilistic truth values
  • G. D. Tré
  • Mathematics, Computer Science
  • Int. J. Intell. Syst.
  • 2002
Extended possibilistic truth values are introduced as a formal means to cope with missing information and the uncertainty model for this logic is proposed, in order to model (linguistic) uncertainty concerning the extended truth value of a proposition. Expand
A Bibliography on Uncertainty Management in Information Systems
  • C. Dyreson
  • Computer Science
  • Uncertainty Management in Information Systems
  • 1996
This is an evolving bibliography of documents on uncertainty and imprecision in information systems, focusing almost exclusively on database and knowledge-base systems, with few references on other kinds of information systems. Expand
Uncertainty Management in Information Systems: From Needs to Solution
This book presents viewpoints of information systems experts on the needs that challenge the uncertainty capabilities of present information systems, and it provides a forum to researchers in uncertainty modeling to describe models and systems that can address these needs. Expand