## Generic well-posedness in some classes of optimization problems.(English)Zbl 0644.49023

Let X be a complete metric space and P be the set of all couples (A,f), where A is a nonempty closed subset of X and $$f: X\to R$$ is a continuous and real-valued function bounded from below. Every pair (A,f)$$\in P$$ gives rise to a constrained optimization problem: find $$x_ 0\in A$$ such that $$f(x_ 0)=\inf \{f(x):$$ $$x\in A\}$$. In this way P can be considered as a set of minimization problems. Let P be endowed with a natural complete metric generated by the Hausdorff metric on the sets A and a uniform metric on the functions f. A problem (A,f)$$\in P$$ is said to be well-posed in the sense of Hadamard if it has a unique solution which depends continuously on the data A and f. We do not require X (or A) to be compact, so a particular problem from P may have not even a solution. But since P is a complete metric space the next question makes sense: does the set $$H=\{(A,f)\in P:$$ (A,f) is Hadamard well-posed$$\}$$ contain a dense and $$G_{\delta}$$-subset of P. In this case we say that most (in the Baire category sense) of the problems in P are Hadamard well-posed. In this paper a positive answer is given to this question. Also, a geometric characterization of Hadamard well-posedness, as well as relations between the Hadamard and other types of well-posedness are given. A class of convex constrained optimization problems is investigated through the above generic point of view.
Reviewer: J.P.Revalski

### MSC:

 49K40 Sensitivity, stability, well-posedness 54E52 Baire category, Baire spaces 90C48 Programming in abstract spaces
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