Logarithmic concavity, unitarity and selfadjointness
Volume 67 / 2005
Banach Center Publications 67 (2005), 335-348
MSC: Primary 47B15; Secondary 47B20.
DOI: 10.4064/bc67-0-26
Abstract
Isometric automorphisms of normed linear spaces are characterized by suitable concavity properties of powers of operators. Bounded selfadjoint operators in Hilbert spaces are described by parallel concavity properties of the exponential group. Unbounded infinitesimal generators of ${\cal C}_0$-groups of Hilbert space operators having concavity properties are characterized as well.
