Christoph Fischbacher

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20232025

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math.SP2025

Complete Non-Selfadjointness of Extensions of Symmetric Operators with Bounded Dissipative Perturbations

Christoph Fischbacher, Andrés Felipe Patiño López, Monika Winklmeier

Using boundary triples, we develop an abstract framework to investigate the complete non-selfadjointness of the maximally dissipative extensions of dissipative operators of the for…

math.SP2025

Maximally dissipative and self-adjoint extensions of $K$ -invariant operators

Christoph Fischbacher, Bart Rosenzweig, Jonathan Stanfill

We introduce the notion of $K$ -invariant operators, $S$ , (in a Hilbert space) with respect to a bounded and boundedly invertible operator $K$ defined via $K^{*} S K = S$ . Conditions such…

math.SP2025

An analysis of non-selfadjoint first-order differential operators with non-local point interactions

Christoph Fischbacher, Danie Paraiso, Chloe Povey-Rowe +1

We study the spectra of non-selfadjoint first-order operators on the interval with non-local point interactions, formally given by $i \partial_{x} + V + k ⟨ δ, \cdot ⟩$ . We giv…

Complete Non-Selfadjointness of Extensions of Symmetric Operators with Bounded Dissipative Perturbations

Maximally dissipative and self-adjoint extensions of K-invariant operators

An analysis of non-selfadjoint first-order differential operators with non-local point interactions

Maximally dissipative and self-adjoint extensions of $K$ -invariant operators