Bernhard H. Haak

collaborators

3 papers

math.FA2026

A weak type $(p, a)$ criterion for operators, and applications

Bernhard H. Haak, El-Maati Ouhabaz

Let $(X, d, I^¼)$ be a space of homogeneous type and $I^c ◯$ an open subset of $X$ . Given a bounded operator $T : L^{p} (I^c ◯) \to L^{q} (I^c ◯)$ for some $1 \leq p \leq q < \infty$ , we give a crite…

math.AP2026

Curved Ingham inequalities and observability of the toroidal Schr{Ã¶}dinger equation

Bernhard H Haak, Philippe Jaming, Ming Wang +1

We prove that solutions of the toroidal Schr{Ã¶}dinger equation can be observed from suitably curved space-time trajectories, thus of zero Lebesgue measure. To do so, we establish…

math.FA2025

A cheap way to closed operator sums

Bernhard H. Haak, Peer Christian Kunstmann

Let $A$ and $B$ be sectorial operators in a Banach space $X$ of angles $I ¨ _{A}$ and $I ¨ _{B}$ , respectively, where $I ¨ _{A} + I ¨ _{B} < I ¨ $ . We present a simple and common approach to results on…

A weak type (p,a) criterion for operators, and applications

Curved Ingham inequalities and observability of the toroidal Schr{Ã¶}dinger equation

A cheap way to closed operator sums

A weak type $(p, a)$ criterion for operators, and applications