We present "Hum-a-song", a system built for music retrieval, and particularly for the Query-By-Humming (QBH) application. According to QBH, the user is able to hum a part of a song that she recalls and would like to learn what this song is, or find other songs similar to it in a large music repository. We present a simple yet efficient approach that maps the problem to time series subsequence matching. The query and the database songs are represented as 2-dimensional time series conveying information about the pitch and the duration of the notes. Then, since the query is a short sequence and we want to find its best match that may start and end anywhere in the database, subsequence matching methods are suitable for this task. In this demo, we present a system that employs and exposes to the user a variety of state-of-the-art dynamic programming methods, including a newly proposed efficient method named SMBGT that is robust to noise and considers all intrinsic problems in QBH; it allows variable tolerance levels when matching elements, where tolerances are defined as functions of the compared sequences, gaps in both the query and target sequences, and bounds the matching length and (optionally) the minimum number of matched elements. Our system is intended to become open source, which is to the best of our knowledge the first non-commercial effort trying to solve QBH with a variety of methods, and that also approaches the problem from the time series perspective.

We study the interaction between global and local techniques in data mining. Specifically, we study the collections of frequent sets in clusters produced by a probabilistic clustering using mixtures of Bernoulli models. That is, we first analyze 0–1 datasets by a global technique (probabilistic clustering using the EM algorithm) and then do a local analysis (discovery of frequent sets) in each of the clusters. The results indicate that the use of clustering as a preliminary phase in finding frequent sets produces clusters that have significantly different collections of frequent sets. We also test the significance of the differences in the frequent set collections in the different clusters by obtaining estimates of the underlying joint density. To get from the local patterns in each cluster back to distributions, we use the maximum entropy technique [17] to obtain a local model for each cluster, and then combine these local models to get a mixture model. We obtain clear improvements to the approximation quality against the use of either the mixture model or the maximum entropy model.