4 papers
math.RA2026
Order embeddings of real matrix domains
Peter Semrl
Let be a positive integer, , and the set of all real symmetric matrices. A nonempty subset $\U \subset S_n$ is called a matrix domain if it is open…
math.FA2026
Order automorphisms of effect algebras
Peter Semrl
An elegant description of the general form of order automorphisms of effect algebras has been known in the complex case. We present a much simpler proof based on the projective geo…
math.FA2025
The study of symmetries: some general techniques
Peter Semrl
Let be the set of all self-adjoint bonded linear operators on and a subset that is pertinent in mathematical foundations of quantum mechanics.…
math.FA2025
Approximate isometries of Hilbert spaces
Peter Semrl
We improve the Hyers-Ulam stability result for isometries of real Hilbert spaces by removing the surjectivity assumption.