论文标题
SONIA:对称块截断的优化算法
SONIA: A Symmetric Blockwise Truncated Optimization Algorithm
论文作者
论文摘要
这项工作为经验风险最小化提供了一种新的算法。该算法通过计算使用一个子空间中使用二阶类型更新的搜索方向来弥合一阶方法和二阶方法之间的差距,并在正交补体中加上缩放的最陡峭的下降步骤。为此,局部曲率信息被合并为帮助解决方案,同时允许算法扩展到机器学习应用程序中经常遇到的大问题维度。提出了理论结果,以确认算法在强凸和非凸病例中都收敛到固定点。还提供了算法的随机变体以及相应的理论保证。数值结果证实了对标准机器学习问题的新方法的优势。
This work presents a new algorithm for empirical risk minimization. The algorithm bridges the gap between first- and second-order methods by computing a search direction that uses a second-order-type update in one subspace, coupled with a scaled steepest descent step in the orthogonal complement. To this end, partial curvature information is incorporated to help with ill-conditioning, while simultaneously allowing the algorithm to scale to the large problem dimensions often encountered in machine learning applications. Theoretical results are presented to confirm that the algorithm converges to a stationary point in both the strongly convex and nonconvex cases. A stochastic variant of the algorithm is also presented, along with corresponding theoretical guarantees. Numerical results confirm the strengths of the new approach on standard machine learning problems.