69 citations · 110 across the 13 of their papers we have counts for
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Maps on real Hilbert spaces preserving the area of parallelograms and a preserver problem on self-adjoint operators
György Pál Gehér
In this paper first we describe all (not necessarily linear or bijective) transformations on with which preserve the area of parallelograms spanned…
Maps on classes of Hilbert space operators preserving measure of commutativity
György Pál Gehér, Gergő Nagy
In this paper first we give a partial answer to a question of L. Molnár and W. Timmermann. Namely, we will describe those linear (not necessarily bijective) transformations on the…
An elementary proof for the non-bijective version of Wigner's theorem
Gy. P. Gehér
The non-bijective version of Wigner's theorem states that a map which is defined on the set of self-adjoint, rank-one projections (or pure states) of a complex Hilbert space and wh…
Asymptotic Behaviour and Cyclic Properties of Weighted Shifts on Directed Trees
György Pál Gehér
In this paper we investigate a new class of operators called weighted shifts on directed trees introduced recently in [Z. J. Jablonski, I. B. Jung and J. Stochel, A Non-hyponormal…