Principles of database and knowledge-base systems, Vol. I
Principles of database and knowledge-base systems, Vol. I
ACM SIGACT News
Recursively indefinite databases (extended abstract)
ICDT '90 Proceedings of the third international conference on database theory on Database theory
PODS '91 Proceedings of the tenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Detecting redundant tuples during query evaluation
PODS '91 Proceedings of the tenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Is there anything better than magic
Proceedings of the 1990 North American conference on Logic programming
On the equivalence of recursive and nonrecursive datalog programs
PODS '92 Proceedings of the eleventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Decidability and undecidability results for boundedness of linear recursive queries
Proceedings of the seventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Equivalences Among Relational Expressions with the Union and Difference Operators
Journal of the ACM (JACM)
Universality of data retrieval languages
POPL '79 Proceedings of the 6th ACM SIGACT-SIGPLAN symposium on Principles of programming languages
Access path selection in a relational database management system
SIGMOD '79 Proceedings of the 1979 ACM SIGMOD international conference on Management of data
The complexity of relational query languages (Extended Abstract)
STOC '82 Proceedings of the fourteenth annual ACM symposium on Theory of computing
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
PODS '94 Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Approximate Query Translation Across Heterogeneous Information Sources
VLDB '00 Proceedings of the 26th International Conference on Very Large Data Bases
Approximate query mapping: Accounting for translation closeness
The VLDB Journal — The International Journal on Very Large Data Bases
Extracting predicates from mining models for efficient query evaluation
ACM Transactions on Database Systems (TODS)
Type inference for datalog and its application to query optimisation
Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Type inference for datalog with complex type hierarchies
Proceedings of the 37th annual ACM SIGPLAN-SIGACT symposium on Principles of programming languages
Towards a logical reconstruction of a theory for locally closed databases
ACM Transactions on Database Systems (TODS)
Query optimization using local completeness
AAAI'97/IAAI'97 Proceedings of the fourteenth national conference on artificial intelligence and ninth conference on Innovative applications of artificial intelligence
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In this paper, we study the ability of data-independent conjunctive expressions (envelopes) to approximate fixpoint of Datalog predicates. We show that no effective procedure exists for finding envelopes that best approximate the fix-point (tight envelopes). Moreover, the problem of determining existence of tight envelopes is undecidable. The relationship between tight envelopes and the boundedness property is explored. Although the property of having tight envelopes seems weaker than boundedness, we note that a predicate can have a tight (lower) envelope iff it is bounded. On the other hand, there exist Datalog predicates that are not bounded but have tight (upper) envelopes. We relax our requirement for tight envelopes and settle for connected envelopes. An algorithm to determine connected envelopes for Datalog predicates is presented. We mention several applications of envelopes.