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Uniqueness of the Index Map in Real K-theory

C. R. Math. Rep. Acad. Sci. Canada Vol. 40 (4) 2018, pp. 101-103
Vol.40 (4) 2018
Ralf Meyer Details
(Received: 2019-03-15 , Revised: 2019-04-01 )
(Received: 2019-03-15 , Revised: 2019-04-01 )

Ralf Meyer,Mathematisches Institut, Georg-August Universitaet Goettingen, Bunsenstrasse 3-5, 37073 Goettingen, Germany; email:


The index map in topological K-theory for real Banach algebra extensions is a natural transformation from the first K-theory of the quotient to the zeroth K-theory of the ideal. We show that any such natural transformation is an integer multiple of the index map.

L’application index dans la K-théorie des extensions d’algèbres de Banach réelles est une transformation naturelle entre le premier K-groupe de l’algèbre quotient et le zéroième K-groupe de l’idéal. On démontre qu’une telle transformation naturelle doit être un multiple intégral de l’application index.

Keywords: Index map, real K-theory

AMS Subject Classification: Index theory, K-theory and operator algebras -including cyclic theory 19K56, 46L80

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