Distributed learning in non-convex environments-Part II: polynomial escape from saddle-points
File(s)nonconvex.pdf (875.66 KB)
Accepted version
Author(s)
Vlaski, Stefan
Sayed, Ali H
Type
Journal Article
Abstract
The diffusion strategy for distributed learning from streaming data employs local stochastic gradient updates along with exchange of iterates over neighborhoods. In Part I [3] of this work we established that agents cluster around a network centroid and proceeded to study the dynamics of this point. We established expected descent in non-convex environments in the large-gradient regime and introduced a short-term model to examine the dynamics over finite-time horizons. Using this model, we establish in this work that the diffusion strategy is able to escape from strict saddle-points in O(1/μ) iterations, where μ denotes the step-size; it is also able to return approximately second-order stationary points in a polynomial number of iterations. Relative to prior works on the polynomial escape from saddle-points, most of which focus on centralized perturbed or stochastic gradient descent, our approach requires less restrictive conditions on the gradient noise process.
Date Issued
2021-01-13
Date Acceptance
2020-11-15
Citation
IEEE Transactions on Signal Processing, 2021, 69, pp.1257-1270
ISSN
1053-587X
Publisher
Institute of Electrical and Electronics Engineers
Start Page
1257
End Page
1270
Journal / Book Title
IEEE Transactions on Signal Processing
Volume
69
Copyright Statement
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Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000622094600009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Engineering, Electrical & Electronic
Engineering
Stochastic optimization
adaptation
non-convex costs
saddle point
escape time
gradient noise
stationary points
distributed optimization
diffusion learning
Publication Status
Published
Date Publish Online
2021-01-13