A Distributed Approach for Optimizing Cascaded Classifier Topologies in Real-Time Stream Mining Systems

In this paper, we discuss distributed optimization techniques for configuring classifiers in a real-time, informationally-distributed stream mining system. Due to the large volume of streaming data, stream mining systems must often cope with overload, which can lead to poor performance and intolerable processing delay for real-time applications. Furthermore, optimizing over an entire system of classifiers is a difficult task since changing the filtering process at one classifier can impact both the feature values of data arriving at classifiers further downstream and, thus, the classification performance achieved by an ensemble of classifiers, as well as the end-to-end processing delay. To address this problem, this paper makes three main contributions. 1) Based upon classification and queuing theoretic models, we propose a utility metric that captures both the performance and the delay of a binary filtering classifier system. 2) We introduce a low-complexity framework for estimating the system utility by observing, estimating, and/or exchanging parameters between the interrelated classifiers deployed across the system. 3) We provide distributed algorithms to reconfigure the system, and analyze the algorithms based upon their convergence properties, optimality, information exchange overhead, and rate of adaptation to nonstationary data sources. We provide results using different video classifier systems.