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Efficient Sparse Recovery via Adaptive Non-Convex Regularizers with Oracle Property
Proceedings of the 30th Conference on Uncertainty in Artificial Intelligence, PMLR R12:441-450, 2014.
Abstract
The main shortcoming of sparse recovery with a convex regularizer is that it is a biased esti- mator and therefore will result in a suboptimal performance in many cases. Recent studies have shown, both theoretically and empirically, that non-convex regularizer is able to overcome the biased estimation problem. Although multiple algorithms have been developed for sparse recov- ery with non-convex regularization, they are ei- ther computationally demanding or not equipped with the desired properties (i.e. optimal recovery error, selection consistency and oracle property). In this work, we develop an algorithm for effi- cient sparse recovery based on proximal gradient descent. The key feature of the proposed algo- rithm is introducing adaptive non-convex regu- larizers whose shrinking threshold vary over it- erations. The algorithm is compatible with most popular non-convex regularizers, achieves a ge- ometric convergence rate for the recovery er- ror, is selection consistent, and most importantly has the oracle property. Based on the proposed framework, we suggest to use a so–called ACCQ regularizer, which is equivalent to zero proximal projection gap adaptive hard-thresholding. Ex- periments with both synthetic data sets and real images verify both the efficiency and effective- ness of the proposed method compared to the state-of-the-art methods for sparse recovery.