Title: Unstable $K$-cohomology algebra is filtered lambda-ring
Author: Donald Yau

MSC: 55N20,55N15,55S05,55S25

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

dyau@math.uiuc.edu

Boardman, Johnson, and Wilson 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 $\lambda$-ring, and vice versa.