Open AccessON EXTREME POINTS OF THE JOINT NUMERICAL RANGE
Author(s) -
Youngoh Yang
Publication year - 1990
Publication title -
tamkang journal of mathematics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.324
H-Index - 18
eISSN - 0049-2930
pISSN - 2073-9826
DOI - 10.5556/j.tkjm.21.1990.4689
Subject(s) - numerical range , extreme point , mathematics , range (aeronautics) , joint (building) , numerical analysis , set (abstract data type) , regular polygon , computer simulation , mathematical analysis , geometry , combinatorics , computer science , statistics , aerospace engineering , structural engineering , engineering , programming language
Our purpose is to study the relationship between the joint numerical range and joint essential numerical range. We give an example of an operator such that the set of all extreme points of the closure of its essential numerical range is not a subset of the set of all exti:eme points of its numerical range. We shall investigate the extreme points of a convex joint essential numerical range.