International Journal of Mathematics and Mathematical Sciences
Volume 2003 (2003), Issue 10, Pages 593-605

Unstable K-cohomology algebra is filtered λ-ring

Donald Yau

Department of Mathematics, University of Illinois at Urbana-Champaign, 1409 W. Green Street, Urbana 61801, IL, USA

Received 3 August 2002

Copyright © 2003 Donald Yau. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Boardman, Johnson, and Wilson (1995) gave a precise formulation for an unstable algebra over a generalized cohomology theory. Modifying their definition slightly in the case of complex K-theory by taking into account its periodicity, we prove that an unstable algebra for complex K-theory is precisely a filtered λ-ring, and vice versa.