103 citations · 113 across the 9 of their papers we have counts for
9 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…
Factorization, majorization, and domination for linear relations
Seppo Hassi, Henk de Snoo
Let , , and be Hilbert spaces. Let be a linear relation from to and let be a linear rela…
Antitonicity of the inverse for selfadjoint matrices, operators, and relations
J. Behrndt, S. Hassi, H. S. V. de Snoo +1
Let and be selfadjoint operators or relations (multivalued operators) acting on a separable Hilbert space and assume that the inequality holds. Then the…
Global and local behavior of zeros of nonpositive type
Henk de Snoo, Henrik Winkler, Michal Wojtylak
A generalized Nevanlinna function with one negative square has precisely one generalized zero of nonpositive type in the closed extended upper halfplane. The fractional line…
Boundary relations and generalized resolvents of symmetric operators
Vladimir Derkach, Seppo Hassi, Mark Malamud +1
The Kre\uın-Naimark formula provides a parametrization of all selfadjoint exit space extensions of a, not necessarily densely defined, symmetric operator, in terms of maximal dissi…