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Fast Newton methods for the group fused lasso
Proceedings of the 30th Conference on Uncertainty in Artificial Intelligence, PMLR R12:216-225, 2014.
Abstract
We present a new algorithmic approach to the group fused lasso, a convex model that approx- imates a multi-dimensional signal via an ap- proximately piecewise-constant signal. This model has found many applications in mul- tiple change point detection, signal compres- sion, and total variation denoising, though existing algorithms typically using first-order or alternating minimization schemes. In this paper we instead develop a specialized pro- jected Newton method, combined with a pri- mal active set approach, which we show to be substantially faster that existing methods. Furthermore, we present two applications that use this algorithm as a fast subroutine for a more complex outer loop: segmenting linear regression models for time series data, and color image denoising. We show that on these problems the proposed method performs very well, solving the problems faster than state- of-the-art methods and to higher accuracy.