论文标题
Frank-Wolfe算法的自信分析
Self-Concordant Analysis of Frank-Wolfe Algorithms
论文作者
论文摘要
通过Frank-Wolfe(FW)的不同变体(又称条件梯度方法)的无投影优化已成为优化机器学习的基石之一,因为在许多情况下,线性最小化的甲骨文的实现比预测便宜得多,并且需要保留一些稀疏性。在许多应用程序中,例如泊松反问题或量子状态断层扫描,损失是由具有无限曲率的自信(SC)函数给出的,这意味着现有FW方法缺乏理论保证。我们使用SC函数的理论为FW方法提供了新的自适应步长,并证明了k迭代后的全局收敛速率O(1/K)。如果该问题允许更强的局部线性最小化甲骨文,则我们构建了一种新型FW方法,具有SC函数的线性收敛速率。
Projection-free optimization via different variants of the Frank-Wolfe (FW), a.k.a. Conditional Gradient method has become one of the cornerstones in optimization for machine learning since in many cases the linear minimization oracle is much cheaper to implement than projections and some sparsity needs to be preserved. In a number of applications, e.g. Poisson inverse problems or quantum state tomography, the loss is given by a self-concordant (SC) function having unbounded curvature, implying absence of theoretical guarantees for the existing FW methods. We use the theory of SC functions to provide a new adaptive step size for FW methods and prove global convergence rate O(1/k) after k iterations. If the problem admits a stronger local linear minimization oracle, we construct a novel FW method with linear convergence rate for SC functions.