Abstract
Sufficient conditions on a space are given which guarantee that the K-theory ring and the ordinary cohomology ring with coefficients over a principal ideal domain are invariants of, respectively, the adic genus and the SNT set. An independent proof of Notbohm's theorem on the classification of the adic genus of BS^3 by KO-theory \lambda-rings is given. An immediate consequence of these results about adic genus is that the power series ring \mathbf{Z} \lbrack \lbrack x \rbrack \rbrack admits uncountably many pairwise non-isomorphic \lambda-ring structures.