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Triply Stochastic Gradients on Multiple Kernel Learning
Proceedings of the 33rd Conference on Uncertainty in Artificial Intelligence, PMLR R15:829-837, 2017.
Abstract
Multiple Kernel Learning (MKL) is highly useful for learning complex data with multi- ple cues or representations. However, MKL is known to have poor scalability because of the expensive kernel computation. Dai et al (2014) proposed to use a doubly Stochastic Gradient Descent algorithm (doubly SGD) to greatly improve the scalability of kernel meth- ods. However, the algorithm is not suitable for MKL because it cannot learn the kernel weights. In this paper, we provide a novel ex- tension to doubly SGD for MKL so that both the decision functions and the kernel weights can be learned simultaneously. To achieve this, we develop the triply Stochastic Gradient De- scent (triply SGD) algorithm which involves three sources of randomness – the data points, the random features, and the kernels, which was not considered in previous work. We prove that our algorithm enjoys similar conver- gence rate as that of doubly SGD. Comparing to several traditional MKL solutions, we show that our method has faster convergence speed and achieved better accuracy. Most impor- tantly, our method makes it possible to learn MKL problems with millions of data points on a normal desktop PC.