Synonyms
Consistent facts; Credulous reasoning; Maybe answer
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 answer to the query when posed simultaneously on all possible worlds.
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Recommended Reading
Grahne G. The problem of incomplete information in relational databases. Berlin: Springer; 1991.
Libkin L. Aspects of partial information in databases. PhD Thesis, University of Pennsylvania. 1994.
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Grahne, G. (2018). Possible Answers. In: Liu, L., Özsu, M.T. (eds) Encyclopedia of Database Systems. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-8265-9_1265
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DOI: https://doi.org/10.1007/978-1-4614-8265-9_1265
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