3 papers
math.FA2026
On the nonnegative rank of positive operators
Roman DrnovÅ¡ek, Marko KandiÄ
In this paper we introduce the concept of a nonnegative rank of a positive operator between ordered vector spaces. In the case of nonnegative matrices, our definit…
math.FA2026
On positive automorphisms of algebras of operators on atomic Archimedean vector lattices
Gregor Cigler, Marko KandiÄ
Let be an Archimedean vector lattice. We investigate subalgebras of consisting of regular operators that contain all rank-one operators of the form $a \otimes…
math.FA2025
Positive commutators of positive square-zero operators
Roman DrnovÅ¡ek, Marko KandiÄ
In this paper we first consider the question which nonnegative matrices are commutators of nonnegative square-zero matrices. Then, we treat infinite-dimensional analogues of these…