Title
Subgradient averaging for multi-agent optimisation with different constraint sets
Abstract
We consider a multi-agent setting with agents exchanging information over a possibly time-varying network, aiming at minimising a separable objective function subject to constraints. To achieve this objective we propose a novel subgradient averaging algorithm that allows for non-differentiable objective functions and different constraint sets per agent. Allowing different constraints per agent simultaneously with a time-varying communication network constitutes a distinctive feature of our approach, extending existing results on distributed subgradient methods. To highlight the necessity of dealing with a different constraint set within a distributed optimisation context, we analyse a problem instance where an existing algorithm does not exhibit a convergent behaviour if adapted to account for different constraint sets. For our proposed iterative scheme we show asymptotic convergence of the iterates to a minimum of the underlying optimisation problem for step sizes of the form ηk+1, η>0. We also analyse this scheme under a step size choice of ηk+1, η>0, and establish a convergence rate of O(lnkk) in objective value. To demonstrate the efficacy of the proposed method, we investigate a robust regression problem and an ℓ2 regression problem with regularisation.
Year
DOI
Venue
2021
10.1016/j.automatica.2021.109738
Automatica
Keywords
DocType
Volume
Distributed optimisation,Multi-agent networks,Parallel algorithms,Subgradient methods,Consensus
Journal
131
Issue
ISSN
Citations 
1
0005-1098
0
PageRank 
References 
Authors
0.34
0
4
Name
Order
Citations
PageRank
Romao Licio100.34
Kostas Margellos216824.95
Giuseppe Notarstefano347042.83
Antonis Papachristodoulou499090.01