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math.FA2024
Friedrichs and Kre\uın type extensions in terms of representing maps
Seppo Hassi, Henk de Snoo
A semibounded operator or relation in a Hilbert space with lower bound has a symmetric extension $S_{\rm f}=S {\, \widehat + \,} (\{0\} \times {\rm mul\,} S…
math.FA2023
Representing maps for semibounded forms and their Lebesgue type decompositions
Seppo Hassi, Henk de Snoo
For a semibounded sesquilinear form in a Hilbert space there exists a representing map from to another Hilbert space ${\mathfrak…
math.FA2023
Sequences of operators, monotone in the sense of contractive domination
Seppo Hassi, Henk de Snoo
A sequence of operators from a Hilbert space to Hilbert spaces which is nondecreasing in the sense of contractive domination is shown to hav…
math.FA2023
Complementation and Lebesgue type decompositions of linear operators and relations
Seppo Hassi, Henk de Snoo
In this paper a new general approach is developed to construct and study Lebesgue type decompositions of linear operators in the Hilbert space setting. The new approach allows…