References
- Halmos PR. A Hilbert space problem book. 2nd ed. New York (NY): Springer; 1982.
- Gustafson K, Rao DKM. Numerical range. The field of values of linear operators and matrices. New York (NY): Springer; 1997.
- Stampfli JG. Minimal range theorems for operators with thin spectra. Pacific J. Math. 1967;23:601–612.
- Li C-K, Choi M-D. Numerical ranges of the powers of an operator. J. Math. Anal. Appl. 2010;365:458–466.
- Choi M-D, Kribs DW, Życzkowski K. Quantum error correcting codes from the compression formalism. Rep. Math. Phys. 2006;58:77–91.
- Choi M-D, Kribs DW, Życzkowski K. Higher-rank numerical ranges and compression problems. Linear Algebra Appl. 2006;418:828–839.
- Choi M-D, Giesinger M, Holbrook JA, Kribs DW. Geometry of higher-rank numerical ranges. Linear Multilinear Algebra. 2008;56:53–64.
- Choi M-D, Holbrook JA, Kribs DW, Życzkowski K. Higher-rank numerical ranges of unitary and normal matrices. Oper. Matrices. 2007;1:409–426.
- Gau H-L, Li C-K, Poon Y-T, Sze N-S. Higher rank numerical ranges of normal matrices. SIAM. J. Matrix Anal. Appl. 2011;32:23–43.
- Gau H-L, Li C-K, Wu PY. Higher-rank numerical ranges and dilations. J. Oper. Theory. 2010;63:181–189.
- Li C-K, Sze N-S. Canonical forms, higher rank numerical ranges, totally isotropic subspaces, and matrix equations. Proc. Amer. Math. Soc. 2008;136:3013–3023.
- Li C-K, Poon Y-T, Sze N-S. Higher rank numerical ranges and low rank perturbations of quantum channels. J. Math. Anal. Appl. 2008;348:843–855.
- Li C-K, Poon Y-T, Sze N-S. Condition for the higher rank numerical range to be non-empty. Linear Multilinear Algebra. 2009;57:365–368.
- Martínez-Avendaño RA. Higher-rank numerical range in infinite-dimensional Hilbert space. Oper. Matrices. 2008;2:249–264.
- Woerdeman H. The higher rank numerical range is convex. Linear Multilinear Algebra. 2008;56:65–67.