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تسجيل مستخدم جديدContinuous Time Frank-Wolfe Does Not Zig-Zag
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The Frank-Wolfe algorithm has regained much interest in its use in structurally constrained machine learning applications. However, one major limitation of the Frank-Wolfe algorithm is the slow local convergence property due to the zig-zagging behavior. We observe that this zig-zagging phenomenon can be viewed as an artifact of discretization, as when the method is viewed as an Euler discretization of a continuous time flow, that flow does not zig-zag. For this reason, we propose multistep Frank-Wolfe variants based on discretizations of the same flow whose truncation errors decay as $O(Delta^p)$, where $p$ is the methods order. We observe speedups using these variants, but at a cost of extra gradient calls per iteration. However, because the multistep methods present better search directions, we show that they are better able to leverage line search and momentum speedups.
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