Efficient On-line Evaluation of Mobility Pattern Queries

Le document attaché a également été présenté à la conférence CIKM 2005, voir http://basepub.dauphine.fr/xmlui/handle/123456789/5214Many applications rely on sequence databases and use extensively pattern-matching queries to retrieve data of interest. This paper extends the traditional pattern-matching expressions to parameterized patterns, featuring variables. Parameterized patterns are more expressive and allow to de ne concisely regular expressions that would be very complex to describe without variables. They can also be used to express additional constraints on patterns' variables. We show that they can be evaluated without additional cost with respect to traditional techniques (e.g., the Knuth-Morris-Pratt algorithm). We describe an algorithm that enjoys low memory and CPU time requirements, and provide experimental results which illustrate the gain of the optimized solution.ou