Efficient random coordinate descent algorithms for large-scale structured nonconvex optimization

In this paper we analyze several new methods for solving nonconvex optimization problems with the objective function formed as a sum of two terms: one is nonconvex and smooth, and another is convex but simple and its structure is known. Further, we consider both cases: unconstrained and linearly constrained nonconvex problems. For optimization problems of … Read more

AN INEXACT PERTURBED PATH-FOLLOWING METHOD FOR LAGRANGIAN DECOMPOSITION IN LARGE-SCALE SEPARABLE CONVEX OPTIMIZATION

This paper studies an inexact perturbed path-following algorithm in the framework of Lagrangian dual decomposition for solving large-scale separable convex programming problems. Unlike the exact versions considered in the literature, we propose to solve the primal subproblems inexactly up to a given accuracy. This leads to an inexactness of the gradient vector and the Hessian … Read more

COMPUTATIONAL COMPLEXITY OF INEXACT GRADIENT AUGMENTED LAGRANGIAN METHODS: APPLICATION TO CONSTRAINED MPC

We study the computational complexity certification of inexact gradient augmented Lagrangian methods for solving convex optimization problems with complicated constraints. We solve the augmented Lagrangian dual problem that arises from the relaxation of complicating constraints with gradient and fast gradient methods based on inexact first order information. Moreover, since the exact solution of the augmented … Read more

A random coordinate descent algorithm for optimization problems with composite objective function and linear coupled constraints

In this paper we present a variant of random coordinate descent method for solving linearly constrained convex optimization problems with composite objective function. If the smooth part has Lipschitz continuous gradient, then the method terminates with an ϵ-optimal solution in O(N2/ϵ) iterations, where N is the number of blocks. For the class of problems with … Read more

Efficient parallel coordinate descent algorithm for convex optimization problems with separable constraints: application to distributed MPC

In this paper we propose a parallel coordinate descent algorithm for solving smooth convex optimization problems with separable constraints that may arise e.g. in distributed model predictive control (MPC) for linear network systems. Our algorithm is based on block coordinate descent updates in parallel and has a very simple iteration. We prove (sub)linear rate of … Read more

Rate analysis of inexact dual first order methods: Application to distributed MPC for network systems

In this paper we propose two dual decomposition methods based on inexact dual gradient information for solving large-scale smooth convex optimization problems. The complicating constraints are moved into the cost using the Lagrange multipliers. The dual problem is solved by inexact first order methods based on approximate gradients and we prove sublinear rate of convergence … Read more

An interior-point Lagrangian decomposition method for separable convex optimization

In this paper we propose a distributed algorithm for solving large-scale separable convex problems using Lagrangian dual decomposition and the interior-point framework. By adding self-concordant barrier terms to the ordinary Lagrangian we prove under mild assumptions that the corresponding family of augmented dual functions is self-concordant. This makes it possible to efficiently use the Newton … Read more

Application of a smoothing technique to decomposition in convex optimization

Dual decomposition is a powerful technique for deriving decomposition schemes for convex optimization problems with specific structure. Although the Augmented Lagrangian is computationally more stable than the ordinary Lagrangian, the \textit{prox-term} destroys the separability of the given problem. In this paper we use another approach to obtain a smooth Lagrangian, based on a smoothing technique … Read more