Beyond itemsets: mining frequent featuresets over structured items

We assume a dataset of transactions generated by a set of users over structured items where each item could be described through a set of features. In this paper, we are interested in identifying the frequent featuresets (set of features) by mining item transactions. For example, in a news website, items correspond to news articles, the features are the named-entities/topics in the articles and an item transaction would be the set of news articles read by a user within the same session. We show that mining frequent featuresets over structured item transactions is a novel problem and show that straightforward extensions of existing frequent itemset mining techniques provide unsatisfactory results. This is due to the fact that while users are drawn to each item in the transaction due to a subset of its features, the transaction by itself does not provide any information about such underlying preferred features of users. In order to overcome this hurdle, we propose a featureset uncertainty model where each item transaction could have been generated by various featuresets with different probabilities. We describe a novel approach to transform item transactions into uncertain transaction over featuresets and estimate their probabilities using constrained least squares based approach. We propose diverse algorithms to mine frequent featuresets. Our experimental evaluation provides a comparative analysis of the different approaches proposed.