Abstract
The subgradient projection iteration is a classical method for solving a convex inequality. Motivated by works of Polyak and of Crombez, we present and analyze a more general method for finding a fixed point of a cutter, provided that the fixed point set has nonempty interior. Our assumptions on the parameters are more general than existing ones. Various limiting examples and comparisons are provided.
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Notes
In fact, \(U_r\) is not even a relaxed cutter in the sense of [2, Definition 2.1.30].
\(U_{r,\eta }\) can also be called a generalized relaxation of \(T\) with relaxation parameter \(\eta \); see [2, Definition 2.4.1].
This observation is a due to a referee.
If we replace Fréchet differentiability by mere continuity, then we may consider a selection of the subdifferential operator \(\partial f\) instead.
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Acknowledgments
The authors thank two anonymous referees for careful reading, constructive comments, and for bringing additional references to our attention. The authors also thank Jeffrey Pang for helpful discussions and for pointing out additional references. HHB was partially supported by a Discovery Grant and an Accelerator Supplement of the Natural Sciences and Engineering Research Council of Canada (NSERC) and by the Canada Research Chair Program. CW is partially supported by a Grant from Shanghai Municipal Commission for Science and Technology (13ZR1455500). XW is partially supported by a Discovery Grant of NSERC. JX is partially supported by NSERC Grants of HHB and XW.
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Bauschke, H.H., Wang, C., Wang, X. et al. On the Finite Convergence of a Projected Cutter Method. J Optim Theory Appl 165, 901–916 (2015). https://doi.org/10.1007/s10957-014-0659-7
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DOI: https://doi.org/10.1007/s10957-014-0659-7
Keywords
- Convex function
- Cutter
- Fejér monotone sequence
- Finite convergence
- Quasi firmly nonexpansive mapping
- Subgradient projector