Projection-free optimization via different variants of the Frank-Wolfe (FW) 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), k being the iteration counter. If the problem can be represented by a local linear minimization oracle, we are the first to propose a FW method with linear convergence rate without assuming neither strong convexity nor a Lipschitz continuous gradient.

通过理论建立不同变体的 Frank-Wolfe（FW）算法的自适应步长，对一些机器学习及物理学问题，能够得到无需映射和保留稀疏性的优化，且对于具有无限曲率的自共轭函数，也可以获得全局收敛速率为 O(1/k) 或线性收敛速率的新的 FW 方法。

Frank-Wolfe算法的自共轭分析