2 papers
math.FA2025
A distance between operators acting in different Hilbert spaces and operator convergence
Olaf Post, Jan Simmer
The aim of the present article is to give an introduction to the concept of quasi-unitary equivalence and to define several (pseudo-)metrics on the space of self-adjoint operators…
math.SP2025
Quasi-unitary equivalence and generalised norm resolvent convergence
Olaf Post, Jan Simmer
The purpose of this article is to give a short introduction to the concept of quasi-unitary equivalence of quadratic forms and its consequences. In particular, we improve an estima…