Abstract
Let H be an infinite-dimensional real Hilbert space equipped with the scalar product (⋅,⋅) H . Let us consider three linear bounded operators,
We define the functions
where a i ∈H and α i ∈ℝ. In this paper, we discuss the closure and the convexity of the sets Φ H ⊂ℝ2 and F H ⊂ℝ3 defined by
Our work can be considered as an extension of Polyak’s results concerning the finite-dimensional case.
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Baccari, A., Samet, B. An Extension of Polyak’s Theorem in a Hilbert Space. J Optim Theory Appl 140, 409–418 (2009). https://doi.org/10.1007/s10957-008-9457-4
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DOI: https://doi.org/10.1007/s10957-008-9457-4