Poster
Fast Stochastic Composite Minimization and an Accelerated Frank-Wolfe Algorithm under Parallelization
Benjamin Dubois-Taine · Francis Bach · Quentin Berthet · Adrien Taylor
Hall J (level 1) #837
Keywords: [ frank-wolfe ] [ Convex Optimization ] [ acceleration ] [ randomized smoothing ] [ Conditional Gradient ]
Abstract:
We consider the problem of minimizing the sum of two convex functions. One of those functions has Lipschitz-continuous gradients, and can be accessed via stochastic oracles, whereas the other is simple''. We provide a Bregman-type algorithm with accelerated convergence in function values to a ball containing the minimum. The radius of this ball depends on problem-dependent constants, including the variance of the stochastic oracle. We further show that this algorithmic setup naturally leads to a variant of Frank-Wolfe achieving acceleration under parallelization. More precisely, when minimizing a smooth convex function on a bounded domain, we show that one can achieve an primal-dual gap (in expectation) in iterations, by only accessing gradients of the original function and a linear maximization oracle with computing units in parallel. We illustrate this fast convergence on synthetic numerical experiments.
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