TY  - JOUR
A1  - Baumgärtel, Hellmut
A1  - Lledo, Fernando
T1  - Duality of compact groups and Hilbert C*-systems for C*-algebras with a nontrivial center
N2  - In this paper we present duality theory for compact groups in the case when the C*-algebra A, the fixed point algebra of the corresponding Hilbert C*-system (F, 9), has a nontrivial center Z superset of C1 and the relative commutant satisfies the minimality condition A' boolean AND F = Z, as well as a technical condition called regularity. The abstract characterization of the mentioned Hilbert C*-system is expressed by means of an inclusion of C*- categories T-c < T, where T-c is a suitable DR-category and T a full subcategory of the category of endomorphisms of A. Both categories have the same objects and the arrows of T can be generated from the arrows of T-c and the center Z. A crucial new element that appears in the present analysis is an abelian group C(G), which we call the chain group of G, and that can be constructed from certain equivalence relation defined on (G) over cap, the dual object of G. The chain group, which is isomorphic to the character group of the center of g, determines the action of irreducible endomorphisms of A when restricted to Z. Moreover, C(g) encodes the possibility of defining a symmetry epsilon also for the larger category T of the previous inclusion
Y1  - 2004
SN  - 0129-167X
ER  - 
TY  - JOUR
A1  - Lledó, Fernando
T1  - Dual group actions on C*-algebras and their description by Hilbert extensions
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Baumgärtel, Hellmut
A1  - Jurke, Matthias
A1  - Lledó, Fernando
T1  - Twisted duality for the CAR-algebra
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Lledó, Fernando
T1  - A family of examples with quantum constraints
Y1  - 1997
ER  - 
TY  - BOOK
A1  - Baumgärtel, Hellmut
A1  - Jurke, Matthias
A1  - Lledó, Fernando
T1  - Symmetrie und Quantentheorie
T3  - Preprint / Universität Potsdam, Institut für Mathematik
Y1  - 1995
VL  - 1995, 6
PB  - Univ.
CY  - Potsdam
ER  - 
TY  - JOUR
A1  - Baumgärtel, Hellmut
A1  - Jurke, Matthias
A1  - Lledó, Fernando
T1  - On free nets over Minkowski space
Y1  - 1995
ER  - 
TY  - THES
A1  - Lledó, Fernando
T1  - Algebraic properties of massless free nets
Y1  - 1998
CY  - Potsdam
ER  - 
TY  - BOOK
A1  - Baumgärtel, Hellmut
A1  - Jurke, Matthias
A1  - Lledó, Fernando
T1  - A remark on covariant and causal nets of CAR-resp.CCR-type local algebras assigned to the irreducible unitary representation of the poincare group labeled by (m>0, s, +)
T3  - Preprint / SFB 288, Differentialgeometrie und Quantenphysik
Y1  - 1994
VL  - 120
CY  - Berlin
ER  - 
TY  - BOOK
A1  - Baumgärtel, Hellmut
A1  - Jurke, Matthias
A1  - Lledó, Fernando
T1  - Mathematische Strukturen passen auf die Natur : Reflexionen über das Wechselverhältnis von Mathematik und Physik
T3  - Preprint / Universität Potsdam, Institut für Mathematik
Y1  - 1994
VL  - 1994, 18
PB  - Univ.
CY  - Potsdam
ER  - 
TY  - JOUR
A1  - Baumgärtel, Hellmut
A1  - Lledó, Fernando
T1  - Some results on superselection structures for C*-algebras with nontrivial center
Y1  - 1997
SN  - 981-02-3984-X
ER  - 
TY  - JOUR
A1  - Baumgärtel, Hellmut
A1  - Lledó, Fernando
T1  - Superselection structures for C*-algebras with nontrivial center
Y1  - 1997
ER  - 
TY  - BOOK
A1  - Lledó, Fernando
T1  - A family of examples with quantum constraints
T3  - Preprint / Universität Potsdam, Institut für Mathematik
Y1  - 1996
VL  - 1996, 01
PB  - Univ.
CY  - Potsdam
ER  - 
TY  - BOOK
A1  - Baumgärtel, Hellmut
A1  - Lledó, Fernando
T1  - Dual group actions on C*-algebras and their description by Hilbert extensions
T3  - Preprint / SFB 288, Differentialgeometrie und Quantenphysik
Y1  - 2000
VL  - 445
PB  - Techn. Univ.
CY  - Berlin
ER  - 
TY  - BOOK
A1  - Baumgärtel, Hellmut
A1  - Jurke, Matthias
A1  - Lledó, Fernando
T1  - Twisted duality for the CAR-algebra
T3  - Preprint / SFB 288, Differentialgeometrie und Quantenphysik
Y1  - 1999
UR  - http://www-sfb288.math.tu-berlin.de/Publications/Preprints.html
VL  - 401
PB  - Techn. Univ.
CY  - Berlin
ER  - 
TY  - BOOK
A1  - Grundling, H.
A1  - Lledó, Fernando
T1  - Local quantum constraints
T3  - Preprint / SFB 288, Differentialgeometrie und Quantenphysik
Y1  - 1999
VL  - 402
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Lledó, Fernando
T1  - Contributions to operator theory in spaces with an indefinite metric, the Heinz Langer anniversary volume, A. S. Dijksma ... eds.; Basel [u.a.], Birkhäuser, 1998, ISBN 3-7643-6003-8
Y1  - 1999
ER  -