Extreme points of the intersection and the union of some operator balls
Tóm tắt
The extreme points of the set {A: A
*
A≤R
2,AA
*≤R
2} of operators acting in then-dimensional Euclidean space are investigated. Forn=2 a complete description of this set is given. For the set {A: A
*
A≤R
2} ∪ {A: AA
*≤R
2} the extreme points are described for alln.
Tài liệu tham khảo
T. Ando. Extreme points of an intersection of operator intervals. InInternational Mathematics Conference '94 (Kaohsiung, 1994), pages 1–18, River Edge, NJ, 1996. World Sci. Publishing.
G.R. Belitskii and Yu.I. Lyubich.Matrix norms and their representations. Birkhäuser, 1988.