Teaching
Mathematics B1, B2 for chemistry students.
Functional analysis and operator theory for mathematics students.
Research
Structure and spectral theory of linear operators on Banach spaces
Spectral decompositions and local spectra
Nonnegative matrices and operators in ordered Banach spaces
Operator semigroups and cosine operator functions
Finite-dimensional positive linear systems
Most important Publications
1. (with K.-H. Förster) On nonnegative realizations of rational matrix functions and nonnegative input-output systems, pp. 89-104 in: Operator Theory: Advances and Applications, Vol. 103, Birkhauser Verlag, Basel, 1998. MR 99f:93022.
2. Periodic groups of operators in Banach spaces, Proc. Amer. Math. Soc., 126 (1998), 1433-1444. MR 98j:47081.
3. (with K.-H. Förster) The index of triangular operator matrices, Proc. Amer. Math. Soc., 128 (2000), 1167-1176. MR 2000i:47003.
4. (with K.-H. Förster) Nonnegative realizations of matrix transfer functions, Lin. Algebra Appl., 311 (2000), 107-129. MR 2001b:93014.
5. (with J. Zemánek) A resolvent condition implying power boundedness, Studia Math. (Warszawa), 134 (1999), 143-151.
6. Inverse elementary divisor problems for nonnegative matrices, Operators and Matrices, 5/2 (2011), 289-301.
7. Multiplicites, generalized Jacobi matrices, and symmetric operators, Journal of Operator Theory, 65/1 (2011), 211-232.
8. Subnormal operators, cyclic vectors and reductivity, Studia Mathematica, 216 (2013), 97-109.
9. On contractions in Hilbert space, Acta Scientiarium Mathematicarum-Szeged, 79/1-2 (2013), 235-251.
10. Orthonormal Jordan bases in finite dimensional Hilbert spaces, Operators and Matrices, 9/1 (2015), 189-201.