On the properties and characterization of connection-trap-free schemes
PODS '86 Proceedings of the fifth ACM SIGACT-SIGMOD symposium on Principles of database systems
Answering queries on embedded-complete database schemes
Journal of the ACM (JACM)
Independent and separable database schemes
SIAM Journal on Computing
Database states and their tableaux
ACM Transactions on Database Systems (TODS)
On the foundations of the universal relation model
ACM Transactions on Database Systems (TODS)
Consequences of assuming a universal relation
ACM Transactions on Database Systems (TODS)
A characterization of globally consistent databases and their correct access paths
ACM Transactions on Database Systems (TODS)
Computational problems related to the design of normal form relational schemas
ACM Transactions on Database Systems (TODS)
Efficient optimization of a class of relational expressions
ACM Transactions on Database Systems (TODS)
Testing implications of data dependencies
ACM Transactions on Database Systems (TODS)
Equivalences Among Relational Expressions with the Union and Difference Operators
Journal of the ACM (JACM)
Variations on the Common Subexpression Problem
Journal of the ACM (JACM)
Testing satisfaction of functional dependencies
Journal of the ACM (JACM)
Efficient query answering in the representative instance approach
PODS '85 Proceedings of the fourth ACM SIGACT-SIGMOD symposium on Principles of database systems
Can we use the universal instance assumption without using nulls?
SIGMOD '81 Proceedings of the 1981 ACM SIGMOD international conference on Management of data
Assumptions in relational database theory
PODS '82 Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems
PODS '82 Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems
Query answering and schema analysis under the weak instance model
Query answering and schema analysis under the weak instance model
Theory of Relational Databases
Theory of Relational Databases
Efficient updates to independent schemes in the weak instance model
SIGMOD '90 Proceedings of the 1990 ACM SIGMOD international conference on Management of data
Database design for incomplete relations
ACM Transactions on Database Systems (TODS)
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Simple chase join expressions are relational algebra expressions, involving only projection and join operators, defined on the basis of the functional dependencies associated with the database scheme. They are meaningful in the weak instance model, because for certain classes of schemes, including independent schemes, the total projections of the representative instance can be computed by means of unions of simple chase join expressions. We show how unions of simple chase join expressions can be optimized efficiently, without constructing and chasing the corresponding tableaux. We also present efficient algorithms for testing containment and equivalence, and for optimizing individual simple chase join expressions.