Abstract. Mining frequent itemsets from transactional datasets is a well known problem with good algorithmic solutions. In the case of uncertain data, however, several new techniques have been proposed. Unfortunately, these proposals often suffer when a lot of items occur with many different probabilities. Here we propose an approach based on sampling by instantiating "possible worlds" of the uncertain data, on which we subsequently run optimized frequent itemset mining algorithms. As such we gain efficiency at a surprisingly low loss in accuracy. These is confirmed by a statistical and an empirical evaluation on real and synthetic data.
Abstract-Mining frequent itemsets from transactional datasets is a well known problem with good algorithmic solutions. Most of these algorithms assume that the input data is free from errors. Real data, however, is often affected by noise. Such noise can be represented by uncertain datasets in which each item has an existence probability. Recently, Bernecker et al. (2009) proposed the frequentness probability; i.e., the probability that a given itemset is frequent, to select itemsets in an uncertain database. A dynamic programming approach to evaluate this measure was given as well. We argue, however, that for the setting of Bernecker et al. (2009), that assumes independence between the items, already well-known statistical tools exist. We show how the frequentness probability can be approximated extremely accurately using a form of the central limit theorem. We experimentally evaluated our approximation and compared it to the dynamic programming approach. The evaluation shows that our approximation method is extremely accurate even for very small databases while at the same time it has much lower memory overhead and computation time.
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