arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.10914stat.MLcs.LG
收藏

混合线性回归的交替极小化超线性收敛

Alternating Minimization Converges Super-Linearly for Mixed Linear Regression

UC Berkeley(加州大学伯克利分校)

Avishek Ghosh, Kannan Ramchandran

摘要:

本文研究了混合随机线性方程组的求解问题。我们有来自多个线性回归的未标记观测值,每个观测值对应于其中一个回归模型。目标是从观测中学习线性回归。传统上,交替最小化(AM)(这是期望最大化(EM)的变体)被用来解决这个问题。AM迭代地在标签的估计和用估计的标签解决回归问题之间交替。经验上,可以观察到,对于包括混合线性回归在内的各种非凸问题,AM与基于梯度的算法相比以快得多的速率收敛。然而,现有的理论表明AM和基于梯度的方法具有相似的收敛速率,未能捕获这种经验行为。在本文中,我们关闭这个差距之间的理论和实践的特殊情况下的混合物的$2$线性回归。我们表明,提供适当的初始化,AM享有\emph{super-linear}率的收敛在某些参数制度。据我们所知,这是第一个工作,理论上建立了这样的速度为AM。因此,如果我们想将未知回归恢复到$ε$的错误(在$\ell_2$范数中),AM只需要$\mathcal{O}(\log \log (1/ε))$迭代。此外,我们比较AM与基于梯度的启发式算法的经验,并表明AM占主导地位的迭代复杂度以及挂钟时间。

英文摘要:

We address the problem of solving mixed random linear equations. We have unlabeled observations coming from multiple linear regressions, and each observation corresponds to exactly one of the regression models. The goal is to learn the linear regressors from the observations. Classically, Alternating Minimization (AM) (which is a variant of Expectation Maximization (EM)) is used to solve this problem. AM iteratively alternates between the estimation of labels and solving the regression problems with the estimated labels. Empirically, it is observed that, for a large variety of non-convex problems including mixed linear regression, AM converges at a much faster rate compared to gradient based algorithms. However, the existing theory suggests similar rate of convergence for AM and gradient based methods, failing to capture this empirical behavior. In this paper, we close this gap between theory and practice for the special case of a mixture of $2$ linear regressions. We show that, provided initialized properly, AM enjoys a \emph{super-linear} rate of convergence in certain parameter regimes. To the best of our knowledge, this is the first work that theoretically establishes such rate for AM. Hence, if we want to recover the unknown regressors upto an error (in $\ell_2$ norm) of $ε$, AM only takes $\mathcal{O}(\log \log (1/ε))$ iterations. Furthermore, we compare AM with a gradient based heuristic algorithm empirically and show that AM dominates in iteration complexity as well as wall-clock time.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑