Numerical Ranges of Hilbert Space Operators

Hwa-Long Gau is Professor in the Department of Mathematics at National Central University, Taiwan. Together with Pei Yuan Wu, he has co-authored over 40 publications on numerical range problems. One of them, Zero-dilation index of a finite matrix (2014), is currently the most-downloaded article in 'Linear Algebra and its Applications'. Pei Yuan Wu is Professor Emeritus in the Department of Applied Mathematics of National Chiao Tung University. He has been working in operator theory and matrix analysis for 45 years, recently focusing on the numerical ranges of operators and matrices. He was awarded the 16th Béla Szőkefalvi-Nagy Medal by the Bolyai Institute of University of Szeged in 2015.

• Preface; 0. Preliminaries in Operator Theory; 1. Numerical Range; 2. Numerical Ranges of Special Operators; 3. Numerical Contraction; 4. Algebraic and Essential Numerical Ranges 5. Numerical Range and Dilation; 6. Numerical Range of Finite Matrix; 7. Numerical Range of Sn-Matrix; 8. Generalized Numerical Ranges; Appendix: Convex Set.

'All in all, this is a well-written and useful book dedicated to a special subject in the realm of single operator theory, which will be helpful to every working mathematician somehow involved with numerical range, as well as to graduate students going into this research field. I have kept my copy on that special bookshelf near my desk within hands' reach.' Carlos S. Kubrusly, zbMATH Open