Adams conjecture




Stable Homotopy theory



The Adams conjecture is a statement about triviality of spherical fibrations associated to certain formal differences of vector bundles (K-theory classes) via the J-homomorphism. The conjecture was stated in (Adams 63, conjecture 1.2), for vector bundles of rank up to two over a finite CW-complex, which was proven in (Adams 63, theorem 1.4). A general proof was then given in (Quillen 71).

The Adams conjecture/Adams-Quillen theorem serves a central role in the identification of the image of the J-homomorphism.


Let XX be (the homotopy type of) a topological space. For V:XBOV \;\colon\; X \longrightarrow B O classifying a real vector bundle on XX, the corresponding spherical fibration is classified by the composite

J(V):XVBOJBGL 1(𝕊) J(V) \;\colon\; X \stackrel{V}{\longrightarrow} B O \stackrel{J}{\longrightarrow} B GL_1(\mathbb{S})

with the delooped J-homomorphism. This descends to a map from topological K-theory to spherical fibrations.

Now for LL a line bundle on some XX and for non-vanishing kk \in \mathbb{Z}, John Adams observed that the spherical fibration associated with the difference L kLKO(X)L^{\otimes k} - L \in K O(X) has the property that some kk-fold multiple of it has trivial spherical fibration, hence that there is NN \in \mathbb{N} for which

J( k N(L kL))=0. J\left( \oplus^{k^N} (L^{\otimes k} - L) \right) = 0 \,.

Noticing that LL k=Ψ k(L)L \mapsto L^{\otimes^k} = \Psi^k(L) is the kkth Adams operation on K-theory applied to the line bundle LL, John Adams then conjectured that the above is true for all vector bundles VV in the form

J( k N(Ψ k(V)V))=0. J\left( \oplus^{k^N} (\Psi^k(V) - V) \right) = 0 \,.



The conjecture originates in:

  • John Adams, On the groups J(X)J(X) I: Topology, 2 (1963) pp. 181–195

Textbook accounts:


The proof of the Adams conjecture is originally due to

The proof using algebraic geometry is due to

  • Dennis Sullivan, Genetics of homotopy theory and the Adams conjecture, The Annals of Mathematics, Second Series, Vol. 100, No. 1 (Jul., 1974), pp. 1-79 (JSTOR, pdf)

Yet another proof via Becker-Gottlieb transfer is due to

  • J. Becker, D. Gottlieb, The transfer map and fiber bundles Topology , 14 (1975)

In equivariant cohomology

The generalization to equivariant cohomology (equivariant K-theory) is discussed in

  • Tammo tom Dieck, theorem 11.3.8 in Transformation Groups and Representation Theory Lecture Notes in Mathematics 766 Springer 1979

  • Z. Fiedorowicz, H. Hauschild, Peter May, theorem 0.4 of Equivariant algebraic K-theory, Equivariant algebraic K-theory, Algebraic K-Theory. Springer, Berlin, Heidelberg, 1982. 23-80 (pdf)

  • Henning Hauschild, Stefan Waner, theorem 0.1 of The equivariant Dold theorem mod kk and the Adams conjecture, Illinois J. Math. Volume 27, Issue 1 (1983), 52-66. (euclid:1256065410)

  • Kuzuhisa Shimakawa, Note on the equivariant KK-theory spectrum, Publ. RIMS, Kyoto Univ. 29 (1993), 449-453 (pdf, doi)

  • Christopher French, theorem 2.4 in The equivariant JJ–homomorphism for finite groups at certain primes, Algebr. Geom. Topol. Volume 9, Number 4 (2009), 1885-1949 (euclid:1513797069)

Last revised on January 3, 2021 at 02:18:14. See the history of this page for a list of all contributions to it.