Ill-Posed Problems and Regularization

  • Victor Isakov
Part of the Applied Mathematical Sciences book series (AMS, volume 127)


In this chapter we consider the equation
$$ Ax = y $$
linear) continuous operator acting from a subset X of a Banach space into a subset Y of another Banach space, and xX is to be found given y. We discuss solvability of this equation when A −1 does not exist by outlining basic results of the theory created in the 1960s by Ivanov, John, Lavrent’ev, and Tikhonov. In Section 2.1 we give definitions of well- and ill-posedness, together with important illustrational examples. In Section 2.2 we describe a class of equations (2.0) that can be numerically solved in a stable way. Section 2.3 is to the variational construction of algorithms of solutions by minimizing Tikhonov stabilizing fimctionals. In Section 2.4 we show that stability estimates for equation (2.0) imply convergence rates for numerical algorithms and discuss the relation between convergence of these algorithms and the existence of a solution to (2.0). The final section, Section 2.5, describes some iterative regularization algorithms.


Hilbert Space Banach Space Heat Equation Conjugate Gradient Method Adjoint Operator 
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Copyright information

© Springer Science+Business Media New York 1998

Authors and Affiliations

  • Victor Isakov
    • 1
  1. 1.Department of Mathematics and StatisticsThe Wichita State UniversityWichitaUSA

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