On the square root of a positive selfadjoint operator
Z Sebestyén, Z Tarcsay - Periodica Mathematica Hungarica, 2017 - Springer
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On the adjoint of Hilbert space operators
Z Sebestyén, Z Tarcsay - Linear and Multilinear Algebra, 2019 - Taylor & Francis
In general, it is a non-trivial task to determine the adjoint S∗ of an unbounded operator S
acting between two Hilbert spaces. We provide necessary and sufficient conditions for a …
acting between two Hilbert spaces. We provide necessary and sufficient conditions for a …
Adjoint of sums and products of operators in Hilbert spaces
Z Sebestyén, Z Tarcsay - Acta Scientiarum Mathematicarum, 2016 - Springer
We provide sufficient and necessary conditions guaranteeing equations (A+ B)*= A*+ B* and
(AB)*= B* A* concerning densely defined unbounded operators A, B between Hilbert …
(AB)*= B* A* concerning densely defined unbounded operators A, B between Hilbert …
Some new characterizations of a Hermitian matrix and their applications
Y Tian - Complex Analysis and Operator Theory, 2024 - Springer
A square matrix A over the field of complex numbers is said to be Hermitian if A= A∗, the
conjugate transpose of A, while Hermitian matrices are known to be an important class of …
conjugate transpose of A, while Hermitian matrices are known to be an important class of …
Operational calculus for rows, columns, and blocks of linear relations
S Hassi, JP Labrousse, H de Snoo - Advances in Operator Theory, 2020 - Springer
Columns and rows are operations for pairs of linear relations in Hilbert spaces, modelled on
the corresponding notions of the componentwise sum and the usual sum of such pairs. The …
the corresponding notions of the componentwise sum and the usual sum of such pairs. The …
Operators having selfadjoint squares
Z Sebestyén, Z Tarcsay - arXiv preprint arXiv:1403.5914, 2014 - arxiv.org
arXiv:1403.5914v2 [math.FA] 18 Sep 2014 Page 1 arXiv:1403.5914v2 [math.FA] 18 Sep 2014
Operators having selfadjoint squares Zoltán Sebestyén and Zsigmond Tarcsay Abstract. The …
Operators having selfadjoint squares Zoltán Sebestyén and Zsigmond Tarcsay Abstract. The …
On the adjoint of linear relations in Hilbert spaces
A Sandovici - Mediterranean Journal of Mathematics, 2020 - Springer
Assume that HH and KK are two real or complex Hilbert spaces, A a linear relation from HH
to KK, and B a linear relation from KK to HH, respectively. Necessary and sufficient …
to KK, and B a linear relation from KK to HH, respectively. Necessary and sufficient …
Range-kernel characterizations of operators which are adjoint of each other
Z Tarcsay, Z Sebestyén - Advances in Operator Theory, 2020 - Springer
We provide necessary and sufficient conditions for a pair S, T of Hilbert space operators in
order that they satisfy S^*= TS∗= T and T^*= ST∗= S. As a main result we establish an …
order that they satisfy S^*= TS∗= T and T^*= ST∗= S. As a main result we establish an …
[PDF][PDF] A note on two-sided removal and cancellation properties associated with Hermitian matrix
Y Tian - 2021 - scholar.archive.org
A complex square matrix A is said to be Hermitian if A= A∗, the conjugate transpose of A.
We prove that each of the two triple matrix product equalities AA∗ A= A∗ AA∗ and A3= AA∗ …
We prove that each of the two triple matrix product equalities AA∗ A= A∗ AA∗ and A3= AA∗ …
On the sum between a closable operator and a -bounded operator
D Popovici, Z Sebestyén, Z Tarcsay - arXiv preprint arXiv:1409.5711, 2014 - arxiv.org
We provide several perturbation theorems regarding closable operators on a real or
complex Hilbert space. In particular we extend some classical results due to Hess--Kato …
complex Hilbert space. In particular we extend some classical results due to Hess--Kato …