In this paper we consider the following problem. Given a class of episodes and an input sequence of events, find all episodes that occur frequently in the event sequence. We describe the framework and formalize the discovery task in Section 2. Algorithms for discovering all frequent episodes are given in Section 3. They are based on the idea of first finding small frequent episodes, and then progressively looking for larger frequent episodes. Additionally, the algorithms use some simple pattern matching ideas to speed up the recognition of occurrences of single episodes. Section 4 outlines an alternative way of approaching the problem, based on locatingminimal occurrences of episodes
