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Strict convexity of some subsets of Hankel operators |
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| Authors: | Caixing Gu Jonathan E Shapiro |
| Institution: | Department of Mathematics, California Polytechnic State University, San Luis Obispo, California 93407 ; Department of Mathematics, California Polytechnic State University, San Luis Obispo, California 93407 |
| Abstract: | We find some extreme points in the unit ball of the set of Hankel operators and show that the unit ball of the set of compact Hankel operators is strictly convex. We use this result to show that the collection of  lower triangular Toeplitz contractions is strictly convex. We also find some extreme points in certain reduced Cowen sets and discuss cases in which they are or are not strictly convex. |
| Keywords: | Hankel operator Toeplitz operator convex |
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