103 citations · 129 across the 29 of their papers we have counts for
28 papers · 1 filter
Product of nonnegative selfadjoint operators in unbounded settings
Yosra Barkaoui, Seppo Hassi
In this paper, necessary and sufficient conditions are established for the factorization of a closed, in general, unbounded operator into a product of two nonnegative selfad…
An extension and refinement of the theorems of Douglas and Sebestyén for unbounded operators
Yosra Barkaoui, Seppo Hassi
For a closed densely defined operator from a Hilbert space to a Hilbert space , necessary and sufficient conditions are established for the factori…
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…
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…
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…
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…