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July 2016 Generalized 3-circular projections for unitary congruence invariant norms
Abdullah Bin Abu Baker
Banach J. Math. Anal. 10(3): 451-465 (July 2016). DOI: 10.1215/17358787-3599609


A projection P0 on a complex Banach space is generalized 3- circular if its linear combination with two projections P1 and P2 having coefficients λ1 and λ2, respectively, is a surjective isometry, where λ1 and λ2 are distinct unit modulus complex numbers different from 1 and P0P1P2=I. Such projections are always contractive. In this paper, we prove structure theorems for generalized 3-circular projections acting on the spaces of all n×n symmetric and skew-symmetric matrices over C when these spaces are equipped with unitary congruence invariant norms.


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Abdullah Bin Abu Baker. "Generalized 3-circular projections for unitary congruence invariant norms." Banach J. Math. Anal. 10 (3) 451 - 465, July 2016.


Received: 16 March 2015; Accepted: 17 August 2015; Published: July 2016
First available in Project Euclid: 13 May 2016

zbMATH: 1356.46010
MathSciNet: MR3504179
Digital Object Identifier: 10.1215/17358787-3599609

Primary: 46B20
Secondary: 47L05

Keywords: generalized 3-circular projection , isometry , spectral theorem , unitary congruence invariant norm

Rights: Copyright © 2016 Tusi Mathematical Research Group


Vol.10 • No. 3 • July 2016
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