On a function that realizes the maximal spectral type
Volume 124 / 1997
Studia Mathematica 124 (1997), 1-7
DOI: 10.4064/sm-124-1-1-7
Abstract
We show that for a unitary operator U on $L^2(X,μ)$, where X is a compact manifold of class $C^r$, $r ∈ ℕ ∪ {∞,ω}$, and μ is a finite Borel measure on X, there exists a $C^r$ function that realizes the maximal spectral type of U.