Authors:
Zoltán Sebestyén Department of Applied Analysis, Eötvös L. University, Pázmány Péter sétány 1/c., Budapest H-1117, Hungarye-mail: sebesty@cs.elte.hu

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Zsigmond Tarcsay Department of Applied Analysis, Eötvös L. University, Pázmány Péter sétány 1/c., Budapest H-1117, Hungarye-mail: sebesty@cs.elte.hu

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Abstract

T T is selfadjoint if T is a densely defined closed Hilbert space operator. This result of von Neumann can be generalized for not necessarily closed operators: TT always admits a positive selfadjoint extension. The Friedrichs extension also will be obtained whenever TT is assumed to be densely defined. Selfadjointness of TT will be investigated. Densely defined positive operators and their Friedrichs extension A and AF, respectively, will be described by showing the existence of a closable operator T such that A=TT and at the same time AF=TT∗∗.

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Acta Mathematica Hungarica
Language English
Size B5
Year of
Foundation
1950
Volumes
per Year
3
Issues
per Year
6
Founder Magyar Tudományos Akadémia  
Founder's
Address
H-1051 Budapest, Hungary, Széchenyi István tér 9.
Publisher Akadémiai Kiadó
Springer Nature Switzerland AG
Publisher's
Address
H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
CH-6330 Cham, Switzerland Gewerbestrasse 11.
Responsible
Publisher
Chief Executive Officer, Akadémiai Kiadó
ISSN 0236-5294 (Print)
ISSN 1588-2632 (Online)

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