474 research outputs found
A Multi-step Inertial Forward--Backward Splitting Method for Non-convex Optimization
In this paper, we propose a multi-step inertial Forward--Backward splitting
algorithm for minimizing the sum of two non-necessarily convex functions, one
of which is proper lower semi-continuous while the other is differentiable with
a Lipschitz continuous gradient. We first prove global convergence of the
scheme with the help of the Kurdyka-{\L}ojasiewicz property. Then, when the
non-smooth part is also partly smooth relative to a smooth submanifold, we
establish finite identification of the latter and provide sharp local linear
convergence analysis. The proposed method is illustrated on a few problems
arising from statistics and machine learning.Comment: This paper is in company with our recent work on
Forward--Backward-type splitting methods http://arxiv.org/abs/1503.0370
Activity Identification and Local Linear Convergence of Forward--Backward-type methods
In this paper, we consider a class of Forward--Backward (FB) splitting
methods that includes several variants (e.g. inertial schemes, FISTA) for
minimizing the sum of two proper convex and lower semi-continuous functions,
one of which has a Lipschitz continuous gradient, and the other is partly
smooth relatively to a smooth active manifold . We propose a
unified framework, under which we show that, this class of FB-type algorithms
(i) correctly identifies the active manifolds in a finite number of iterations
(finite activity identification), and (ii) then enters a local linear
convergence regime, which we characterize precisely in terms of the structure
of the underlying active manifolds. For simpler problems involving polyhedral
functions, we show finite termination. We also establish and explain why FISTA
(with convergent sequences) locally oscillates and can be slower than FB. These
results may have numerous applications including in signal/image processing,
sparse recovery and machine learning. Indeed, the obtained results explain the
typical behaviour that has been observed numerically for many problems in these
fields such as the Lasso, the group Lasso, the fused Lasso and the nuclear norm
regularization to name only a few.Comment: Full length version of the previous short on
- …