On the Complexity of Parallel Coordinate Descent
Abstract
In this work we study the parallel coordinate descent method (PCDM) proposed by Richt\'arik and Tak\'ac [26] for minimizing a regularized convex function. We adopt elements from the work of Xiao and Lu [39], and combine them with several new insights, to obtain sharper iteration complexity results for PCDM than those presented in [26]. Moreover, we show that PCDM is monotonic in expectation, which was not confirmed in [26], and we also derive the first high probability iteration complexity result where the initial levelset is unbounded.
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