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Register a new userTight Nonparametric Convergence Rates for Stochastic Gradient Descent under the Noiseless Linear Model
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Added by
Raphael Berthier
Publication date
2020
fields
Informatics Engineering
and research's language is
English
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In the context of statistical supervised learning, the noiseless linear model assumes that there exists a deterministic linear relation $Y = langle theta_*, X rangle$ between the random output $Y$ and the random feature vector $Phi(U)$, a potentially non-linear transformation of the inputs $U$. We analyze the convergence of single-pass, fixed step-size stochastic gradient descent on the least-square risk under this model. The convergence of the iterates to the optimum $theta_*$ and the decay of the generalization error follow polynomial convergence rates with exponents that both depend on the regularities of the optimum $theta_*$ and of the feature vectors $Phi(u)$. We interpret our result in the reproducing kernel Hilbert space framework. As a special case, we analyze an online algorithm for estimating a real function on the unit interval from the noiseless observation of its value at randomly sampled points; the convergence depends on the Sobolev smoothness of the function and of a chosen kernel. Finally, we apply our analysis beyond the supervised learning setting to obtain convergence rates for the averaging process (a.k.a. gossip algorithm) on a graph depending on its spectral dimension.
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