10[1]. - Improving Termination Analysis of Active...

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Improving Termination Analysis of Active Rules with Priorities Alain Couchot Laboratoire Cedric-Isid, Conservatoire National des Arts et Métiers, France [email protected] Abstract. This paper presents an algorithm for termination static analysis of active rules with priorities. Active rules termination is an undecidable problem. Several recent works have suggested proving termination by using the concept of triggering graph. We propose here a refinement of these works, exploiting the priorities defined between rules. 1 Introduction We are here interested in the active rules termination problem. The active rules are structured according to paradigm Event-Condition-Action. The active rules termination is an undecidable problem. The majority of works on active rules termination exploit the concept of triggering graph [4] ; the nodes of the graph are rules. Two rules r1 and r2 are connected by a oriented edge from r1 to r2 if the action of r1 can provoke a triggering event of r2 . The presence of cycles in a such graph means a risk of non-termination of the rules set. The absence of cycles in the triggering graph guarantees the termination of the rules set. Some works refine the triggering graph analysis, taking into account the influence of rules conditions [1, 3, 7, 8], the influence of composite events [5, 9], the modular rules design [2, 6]. Our work is based on the following observation : priorities between rules can be used to refine termination analysis. We show in this paper that much more termination cases can be detected using the priorities between rules. 2 Path Sets We introduce here the notions of path set of a rule and path set of a path . The path set serves for replacing the notion of cycle, used in the previous termination algorithms. We suppose that each rule is defined with a numeric priority and that the rules process is the following: 1. Choose a rule instance with the strongest priority in the set of triggered rules instances. 2. Remove the chosen rule instance from the set of the triggered rule instances.
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3. Evaluate the condition.
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This note was uploaded on 06/14/2011 for the course DATABASE 101 taught by Professor - during the Spring '11 term at Aarhus Universitet.

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10[1]. - Improving Termination Analysis of Active...

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