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math.CA2025
On Sesquilinear Forms for Lower Semibounded (Singular) Sturm-Liouville Operators
Jussi Behrndt, Fritz Gesztesy, Seppo Hassi +2
Any self-adjoint extension of a (singular) Sturm-Liouville operator bounded from below uniquely leads to an associated sesquilinear form. This form is characterized in terms of pri…
math.FA2025
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…
math.FA2025
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…