Radu Ioan Bot, Bernd Hofmann: The impact of a curious type of smoothness conditions on convergence rates in l¹-regularization

Author(s):

Radu Ioan Bot
Bernd Hofmann

Title:

Radu Ioan Bot, Bernd Hofmann: The impact of a curious type of smoothness conditions on convergence rates in l¹-regularization

Electronic source:

application/pdf

Preprint series:

Technische Universität Chemnitz, Fakultät für Mathematik (Germany). Preprint 01, 2013

Mathematics Subject Classification:

47J06	[]
65J20	[]
47A52	[]
49J40	[]

Abstract:

Tikhonov-type regularization of linear and nonlinear ill-posed problems in abstract spaces under sparsity constraints gained relevant attention in the past years. Since under some weak assumptions all regularized solutions are sparse if the l¹-norm is used as penalty term, the l¹-regularization was studied by numerous authors although the non-reflexivity of the Banach space l¹ and the fact that such penalty functional is not strictly convex lead to serious difficulties. We consider the case that the sparsity assumption is narrowly missed. This means that the solutions may have an infinite number of nonzero but fast decaying components. For that case we formulate and prove convergence rates results for the l¹-regularization of nonlinear operator equations. In this context, we outline the situations of Hölder rates and of an exponential decay of the solution components.

Keywords:

Nonlinear ill-posed problems, Tikhonov-type regularization, l¹-regularization, sparsity constraints, convergence rates, variational inequalities, source conditions, discrepancy principle

Language:

English

Publication time:

01/2013