TY  - JOUR
AU  - Roman, Marcel
AU  - Sandovici, Adrian
TI  - Adjoint to each other linear relations. Nieminen type criteria
JF  - MONATSHEFTE FUR MATHEMATIK
J2  - MONATSH MATH
PY  - 2021
SN  - 0026-9255
DO  - 10.1007/s00605-021-01579-9
UR  - https://m2.mtmt.hu/api/publication/32083562
ID  - 32083562
N1  - Export Date: 7 September 2022            
            Correspondence Address: Sandovici, A.; Department of Mathematics and Informatics, B-dul Carol I, nr. 11, Romania; email: adrian.sandovici@luminis.ro
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Sandovici, Adrian
TI  - On the Adjoint of Linear Relations in Hilbert Spaces
JF  - MEDITERRANEAN JOURNAL OF MATHEMATICS
J2  - MEDITERR J MATH
VL  - 17
PY  - 2020
IS  - 2
SN  - 1660-5446
DO  - 10.1007/s00009-020-1503-y
UR  - https://m2.mtmt.hu/api/publication/31325292
ID  - 31325292
N1  - Cited By :5            
            Export Date: 7 September 2022            
            Correspondence Address: Sandovici, A.; Department of Mathematics and Informatics, B-dul Carol I, nr. 11, Romania; email: adrian.sandovici@luminis.ro
LA  - English
DB  - MTMT
ER  - 

TY  - GEN
AU  - Souheyb, Dehimi
AU  - Mohammed, Hichem Mortad
TI  - Unbounded operators having self-adjoint or normal powers and some related results
PY  - 2020
UR  - https://m2.mtmt.hu/api/publication/32083554
ID  - 32083554
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Roman, Marcel
AU  - Sandovici, Adrian
TI  - THE SQUARE ROOT OF NONNEGATIVE SELFADJOINT LINEAR RELATIONS IN HILBERT SPACES
JF  - JOURNAL OF OPERATOR THEORY
J2  - J OPERAT THEOR
VL  - 82
PY  - 2019
IS  - 2
SP  - 357
EP  - 367
PG  - 11
SN  - 0379-4024
DO  - 10.7900/jot.2018may24.2226
UR  - https://m2.mtmt.hu/api/publication/31089104
ID  - 31089104
N1  - Cited By :4            
            Export Date: 7 October 2022
AB  - An elementary construction of the square root of nonnegative selfadjoint linear relations in Hilbert spaces is presented.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Sandovici, A.
TI  - A range matrix-type criterion for the self-adjointness of symmetric linear relations
JF  - ACTA MATHEMATICA HUNGARICA
J2  - ACTA MATH HUNG
VL  - 158
PY  - 2019
SP  - 27
EP  - 35
PG  - 9
SN  - 0236-5294
DO  - 10.1007/s10474-018-0883-y
UR  - https://m2.mtmt.hu/api/publication/30440389
ID  - 30440389
N1  - Cited By :2            
            Export Date: 7 September 2022            
            Correspondence Address: Sandovici, A.; Department of Mathematics and Informatics, B-dul Carol I, nr. 11, Romania; email: adrian.sandovici@luminis.ro
AB  - The main objective of this paper is to provide a range-type criterion for the self-adjointness of symmetric linear relations in real or complex Hilbert spaces. The main used ingredient is a matrix whose entries are certain linear relations.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Sandovici, Adrian
TI  - Self-adjointness and skew-adjointness criteria involving powers of linear relations
JF  - JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS
J2  - J MATH ANAL APPL
VL  - 470
PY  - 2019
IS  - 1
SP  - 186
EP  - 200
PG  - 15
SN  - 0022-247X
DO  - 10.1016/j.jmaa.2018.09.063
UR  - https://m2.mtmt.hu/api/publication/30440374
ID  - 30440374
AB  - The main objective of this paper is to provide range-type criteria for the self-adjointness of symmetric linear relations and for the skew-adjointness of skew-symmetric linear relations in real or complex Hilbert spaces, respectively. These range-type criteria involve powers of linear relations.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Sebestyén, Zoltán
AU  - Tarcsay, Zsigmond
TI  - On the adjoint of Hilbert space operators
JF  - LINEAR AND MULTILINEAR ALGEBRA
J2  - LINEAR MULTILINEAR A
VL  - 67
PY  - 2019
IS  - 3
SP  - 625
EP  - 645
PG  - 21
SN  - 0308-1087
DO  - 10.1080/03081087.2018.1430120
UR  - https://m2.mtmt.hu/api/publication/30446535
ID  - 30446535
N1  - Funding Agency and Grant Number: Hungarian Ministry of Human Capacities [NTP-NFTO-17]
            Funding text: Zsigmond Tarcsay was supported by the Hungarian Ministry of Human Capacities [grant number NTP-NFTO-17].
AB  - 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 given operator T to be identical with S*. In our considerations, a central role is played by the operator matrix M-S,M-T = (I -T S I). Our approach has several consequences such as characterizations of closed, normal, skew- and selfadjoint, unitary and orthogonal projection operators in real or complex Hilbert spaces. We also give a self-contained proof of the fact that T*T always has a positive selfadjoint extension.
LA  - English
DB  - MTMT
ER  - 

TY  - JOUR
AU  - Sebestyén, Zoltán
AU  - Tarcsay, Zsigmond
TI  - On the square root of a positive selfadjoint operator
JF  - PERIODICA MATHEMATICA HUNGARICA
J2  - PERIOD MATH HUNG
VL  - 75
PY  - 2017
IS  - 2
SP  - 268
EP  - 272
PG  - 5
SN  - 0031-5303
DO  - 10.1007/s10998-017-0192-1
UR  - https://m2.mtmt.hu/api/publication/3293570
ID  - 3293570
N1  - Cited By :7            
            Export Date: 7 September 2022            
            Correspondence Address: Tarcsay, Z.; Department of Applied Analysis, Pázmány Péter sétány 1/c, Hungary; email: tarcsay@cs.elte.hu
AB  - We provide a short, elementary proof of the existence and uniqueness of the square root in the context of unbounded positive selfadjoint operators on real or complex Hilbert spaces.
LA  - English
DB  - MTMT
ER  -