5 papers
Weak Coupling and Spectral Instability for Neumann Laplacians
Jussi Behrndt, Fritz Gesztesy, Henk de Snoo
We prove an abstract criterion on spectral instability of nonnegative selfadjoint extensions of a symmetric operator and apply this to self-adjoint Neumann Laplacians on bounded Li…
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…