2 citations · 4 across the 5 of their papers we have counts for
5 papers
Commutators greater than a perturbation of the identity
Roman Drnovšek, Marko Kandić
Let and be elements of an ordered normed algebra with unit . Suppose that the element is positive and that for some there exists an elem…
On semigroups of nonnegative functions and positive operators
Roman Drnovšek, Heydar Radjavi
We give extensions of results on nonnegative matrix semigroups which deduce finiteness or boundedness of such semigroups from the corresponding local properties, e.g., from finiten…
An infinite-dimensional generalization of Zenger's lemma
Roman Drnovšek
We prove an infinite-dimensional generalization of Zenger's lemma that was used in the proof of the fact that the convex hull of the point spectrum of a linear operator is containe…
Invariant subspaces for operator semigroups with commutators of rank at most one
Roman Drnovšek
Let X be a complex Banach space of dimension at least 2, and let S be a multiplicative semigroup of operators on X such that the rank of AB - BA is at most 1 for all pairs {A,B} in…
A generalization of Levinger's theorem to positive kernel operators
Roman Drnovšek
We prove some inequalities for the spectral radius of positive operators on Banach function spaces. In particular, we show the following extension of Levinger's theorem. Let be…