3 papers
math.FA2026
Rearrangement Invariant Orthogonal Sums in Krein Spaces. II
Michael A. Dritschel, Alejandra Maestripieri, James Rovnyak
Part I of the paper considered infinite orthogonal sums of regular subspaces in a Krein space (that is, of subspaces which are themselves Krein spaces). How precisely these sums sh…
math.FA2026
Hermitian indices and factorization of selfadjoint operators on a KreÄn space
Michael A. Dritschel, Alejandra Maestripieri, James Rovnyak
The hermitian indices of a selfadjoint operator on a KreÄn space are defined as geometric measures of positivity and negativity of the operator. A different pair…
math.FA2025
Krein-Å mul'jan Theorem Revisited
Santiago gonzalez Zerbo, Alejandra Maestripieri, Francisco MartÃnez PerÃa
We present a generalization of Krein-Å mul'jan theorem which involves several operators. Given bounded selfadjoint operators acting on a Hilbert space $\mathcal{…