Title
Projection methods for ill-posed problems revisited
Abstract
We consider the discretization of least-squares problems for linear ill-posed operator equations in Hilbert spaces. The main subject of this article concerns conditions for convergence of the associated discretized minimum-norm least-squares solution to the exact solution using exact attainable data. The two cases of global convergence (convergence for all exact solutions) or local convergence (convergence for a specific exact solution) are investigated. We review the existing results and prove new equivalent conditions when the discretized solution always converges to the exact solution. An important tool is to recognize the discrete solution operator as an oblique projection. Hence, global convergence can be characterized by certain subspaces having uniformly bounded angles. We furthermore derive practically useful conditions when this holds and put them into the context of known results. For local convergence, we generalize results on the characterization of weak or strong convergence and state some new sufficient conditions. We furthermore provide an example of a bounded sequence of discretized solutions which does not converge at all, not even weakly.
Year
DOI
Venue
2016
10.1515/cmam-2015-0036
COMPUTATIONAL METHODS IN APPLIED MATHEMATICS
Keywords
Field
DocType
Ill-Posed Problems with Exact Data,Projection Methods
Weak convergence,Normal convergence,Mathematical analysis,Compact convergence,Uniform convergence,Convergence tests,Local convergence,Mathematics,Bounded function,Modes of convergence
Journal
Volume
Issue
ISSN
16
2
1609-4840
Citations 
PageRank 
References 
0
0.34
0
Authors
1
Name
Order
Citations
PageRank
Stefan Kindermann129319.60