Given the high volume of content being generated online, it becomes necessary to employ automated techniques to separate out the documents belonging to novel topics from the background discussion, in a robust and scalable manner (with respect to the size of the document set). We present a solution to this challenge based on sparse coding, in which a stream of documents (where each document is modeled as an m-dimensional vector y) can be used to learn a dictionary matrix A of dimension m × k, such that the documents can be approximately represented by a linear combination of a few columns of A. If a new document cannot be represented with low error as a sparse linear combination of these columns, then this is a strong indicator of novelty of the document. We scale up this approach to handle millions of documents by parallelizing sparse coding and dictionary learning, and by using the alternating-directions method to solve the resulting optimization problems. We conduct our experiments on high-performance computing clusters with differing architectures and evaluate our approach on news streams and streaming data from Twitter®. Based on the analysis, we share our insights on the distributed optimization and machine architecture that can help the design of exascale systems supporting data analytics.
['Shiva Prasad Kasiviswanathan', 'Gao Cong', 'Prem Melville', 'Richard D. Lawrence']
Novel document detection for massive data streams using distributed dictionary learning