"Mining Sequential Patterns with Regular Expression Constraints"
Discovering sequential patterns is an important problem in data mining with a
host of application domains including medicine, telecommunications, and the
World Wide Web. Conventional sequential pattern mining systems provide users
with only a very restricted mechanism (based on minimum support) for specifying
patterns of interest. As a consequence, the pattern mining process is
typically characterized by lack of focus and users often end up paying
inordinate computational costs just to be inundated with an overwhelming number
of useless results.
In this paper, we propose the use of Regular Expressions (REs) as a flexible
constraint specification tool that enables user-controlled focus to be
incorporated into the pattern mining process. We develop a family of novel
algorithms (termed SPIRIT -- Sequential Pattern mIning with Regular expressIon
consTraints) for mining frequent sequential patterns that also satisfy
user-specified RE constraints. The main distinguishing factor among the
proposed schemes is the degree to which the RE constraints are enforced to
prune the search space of patterns during computation. Our solutions provide
valuable insights into the tradeoffs that arise when constraints that do not
subscribe to nice properties (like anti-monotonicity) are integrated into the
mining process. A quantitative exploration of these tradeoffs is conducted
through an extensive experimental study on synthetic and real-life data sets.
The experimental results clearly validate the effectiveness of our approach,
showing that speedups of more than an order of magnitude are possible when RE
constraints are pushed deep inside the mining process. Our experimentation
with real-life data also illustrates the versatility of REs as a user-level tool
for focusing on interesting patterns.
Copyright © 2002, IEEE.
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