4 citations · 7 across the 3 of their papers we have counts for
9 papers
Operator norm and numerical radius analogues of Cohen's inequality
Roman Drnovšek
Let be an invertible multiplication operator on , and let be a bounded operator on . In this note we prove that ,…
Sequences of bounds for the spectral radius of a positive operator
Roman Drnovšek
In 1992, Szyld provided a sequence of lower bounds for the spectral radius of a nonnegative matrix , based on the geometric symmetrization of powers of . In 1998, Taşçi and K…
A sharp inequality involving hyperbolic and inverse hyperbolic functions
Roman Drnovšek
We prove that the inequality holds for all . We check with the comput…
A note on Huijsmans-de Pagter problem in ordered Banach algebras
Roman Drnovšek
We give an example of a positive element in some ordered Banach algebra such that its spectrum is equal to and it is not greater than or equal to the unit element o…
On order automorphisms of the effect algebra
Roman Drnovšek
We give short proofs of two Šemrl's descriptions of order automorphisms of the effect algebra. This sheds new light on both formulas that look quite complicated. Our proofs rely on…
On algebras generated by positive operators
Roman Drnovšek
We study algebras generated by positive matrices, i.e., matrices with nonnegative entries. Some of our results hold in more general setting of vector lattices. We reprove and exten…