Design overview of the NAIL] system
Proceedings on Third international conference on logic programming
The Recursive Unsolvability of the Decision Problem for the Class of Definite Formulas
Journal of the ACM (JACM)
Principles of Database Systems
Principles of Database Systems
Introduction to Mathematical Theory of Computation
Introduction to Mathematical Theory of Computation
Characterizing Data Base Dependencies
Proceedings of the 8th Colloquium on Automata, Languages and Programming
Horn clauses and database dependencies (Extended Abstract)
STOC '80 Proceedings of the twelfth annual ACM symposium on Theory of computing
A framework for testing safety and effective computability of extended datalog
SIGMOD '88 Proceedings of the 1988 ACM SIGMOD international conference on Management of data
Towards an efficient evaluation of general queries: quantifier and disjunction processing revisited
SIGMOD '89 Proceedings of the 1989 ACM SIGMOD international conference on Management of data
Logic programming as constructivism: a formalization and its application to databases
PODS '89 Proceedings of the eighth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
A Relational Calculus with Set Operators, Its Safety, and Equivalent Graphical Languages
IEEE Transactions on Software Engineering
Query processing techniques in the summary-table-by-example database query language
ACM Transactions on Database Systems (TODS)
Queries and query processing in object-oriented database systems
ACM Transactions on Information Systems (TOIS)
Safety and translation of relational calculus
ACM Transactions on Database Systems (TODS)
Reactive consistency control in deductive databases
ACM Transactions on Database Systems (TODS)
Two-Dimensional Specification of Universal Quantification in a Graphical Database Query Language
IEEE Transactions on Software Engineering
SCDBR: An Automated Reasoner for Specifications of Database Updates
Journal of Intelligent Information Systems
Independence of logic database queries and update
PODS '90 Proceedings of the ninth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
The power of languages for the manipulation of complex values
The VLDB Journal — The International Journal on Very Large Data Bases
Specifying Active Rules for Database Maintenance
Selected papers from the Eight International Workshop on Foundations of Models and Languages for Data and Objects, Transactions and Database Dynamics
Semantically correct query answers in the presence of null values
EDBT'06 Proceedings of the 2006 international conference on Current Trends in Database Technology
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Not all queries in relational calculus can be answered “sensibly” once disjunction, negation, and universal quantification are allowed. The class of relational calculus queries, or formulas, that have “sensible” answers is called the domain independent class, which is known to be undecidable. Subsequent research has focused on identifying large decidable subclasses of domain independent formulas In this paper we investigate the properties of two such classes the evaluable formulas and the allowed formulas. Although both classes have been defined before, we give simplified definitions, present short proofs of their man properties, and describe a method to incorporate equality.Although evaluable queries have sensible answers, it is not straightforward to compute them efficiently or correctly. We introduce relational algebra normal form for formulas from which form the correct translation into relational algebra is trivial. We give algorithms to transform an evaluable formula into an equivalent allowed formula, and from there into relational algebra normal form. Our algorithms avoid use of the so-called Dom relation, consisting of all constants appearing in the database or the query.Finally, we describe a restriction under which every domain independent formula is evaluable, and argue that evaluable formulas may be the largest decidable subclass of the domain independent formulas that can be efficiently recognized.