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Termination and Confluence by Rule Prioritization
March/April 2003 (vol. 15 no. 2)
pp. 257-270

Abstract—An active database system is a DBMS endowed with active rules, i.e., stored procedures activated by the system when specific events occur. The processing of active rules is characterized by two important properties: termination and confluence. We say that the processing of a set of active rules terminates if, given any initial active database state, the execution of the rules does not continue indefinitely; it is confluent if, for any initial database state, the final state is not influenced by the order of execution of the rules. Finding sufficient conditions for these properties to hold is a nontrivial problem, and the lack of a structured theory for the design of a system of active rules makes the analysis of the two properties more difficult. In this work, we translate a set of rules from any of the existing systems into an internal format; then, we translate the active rules into logical clauses, taking into account the system's execution semantics, and transfer to the active process known simple results about termination and determinism available in the literature for deductive rules.

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Index Terms:
Active databases, database dynamics, deductive databases, termination, determinism.
Sara Comai, Letizia Tanca, "Termination and Confluence by Rule Prioritization," IEEE Transactions on Knowledge and Data Engineering, vol. 15, no. 2, pp. 257-270, March-April 2003, doi:10.1109/TKDE.2003.1185831
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