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Author Klug, Anthony
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Copyright Year ©1988
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Abstract Conjunctive queries are generalized so that inequality comparisons can be made between elements of the query. Algorithms for containment and equivalence of such “inequality queries” are given, under the assumption that the data domains are dense and totally ordered. In general, containment does not imply the existence of homomorphisms (containment mappings), but the homomorphism property does exist for subclasses of inequality queries. A minimization algorithm is defined using the equivalence algorithm. It is first shown that the constants appearing in a query can be divided into “essential” and “nonessential” subgroups. The minimum query can be nondeterministically guessed using only the essential constants of the original query.
ISSN 00045411
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 1988-01-01
Publisher Place New York
e-ISSN 1557735X
Journal Journal of the ACM (JACM)
Volume Number 35
Issue Number 1
Page Count 15
Starting Page 146
Ending Page 160


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Source: ACM Digital Library