Skip to main content
SpringerLink
Log in
Book cover

Encyclopedia of Database Systems pp 2125Cite as

Possible Answers

  • Reference work entry

  • 34 Accesses

Synonyms

Maybe answer; Credulous reasoning; Consistent facts

Definition

In an incomplete database, which is a set of complete databases (possible worlds), the possible answer to a query is the set of tuples that are in the answer to the query, when posed on some possible world. The dual of the possible answer is the certain answer, which consists of all tuples true in the the answer to the query when posed simulatenously on all possible worlds.

Key Points

For more information on the certain and possible answers, as well as on various (partial) orders on incomplete databases, see [1,2].

Cross-references

Certain (and Possible) Answers

Incomplete Information

Naive Tables

This is a preview of subscription content, log in via an institution.

Chapter
USD   29.95
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
eBook
USD   2,500.00
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever

Tax calculation will be finalised at checkout

Purchases are for personal use only

Learn about institutional subscriptions

Recommended Reading

  1. Grahne G. The Problem of Incomplete Information in Relational Databases. Springer, Berlin, 1991.

    MATH  Google Scholar 

  2. Libkin L. Aspects of Partial Information in Databases. PhD Thesis, University of Pennsylvania, 1994.

    Google Scholar 

Download references

Author information

Authors and Affiliations

    Authors
    1. Gösta Grahne
      View author publications

      You can also search for this author in PubMed Google Scholar

    Editor information

    Editors and Affiliations

    1. College of Computing, Georgia Institute of Technology, 266 Ferst Drive, 30332-0765, Atlanta, GA, USA

      LING LIU (Professor) (Professor)

    2. Database Research Group David R. Cheriton School of Computer Science, University of Waterloo, 200 University Avenue West, N2L 3G1, Waterloo, ON, Canada

      M. TAMER ÖZSU (Professor and Director, University Research Chair) (Professor and Director, University Research Chair)

    Rights and permissions

    Reprints and permissions

    Copyright information

    © 2009 Springer Science+Business Media, LLC

    About this entry

    Cite this entry

    Grahne, G. (2009). Possible Answers. In: LIU, L., ÖZSU, M.T. (eds) Encyclopedia of Database Systems. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-39940-9_1265

    Download citation

    Publish with us

    Policies and ethics

    Search

    Navigation