Math 2.0

Algebraic topology Stable homotopy theory and generalized cohomology Theorem

Ravenel conjectures

Builds on Chromatic homotopy theorySpectrumNilpotence theoremPrime number

Statement

Fix a prime number pp. Let K(n)K(n) be the nn-th Morava K-theory, with K(0)=HℚK(0) = H\Q. Let LnL_n be Bousfield localization with respect to the Johnson–Wilson spectrum E(n)E(n), as in chromatic homotopy theory. A finite pp-local spectrum XX has type nn if K(n)∗X≠0K(n)_* X \ne 0 and K(m)∗X=0K(m)_* X = 0 for all m<nm < n. The following conjectures of Ravenel are theorems.

  1. (Nilpotence) A self-map f ⁣:ΣdX→Xf \colon \Sigma^d X \to X of a finite pp-local spectrum is nilpotent if K(n)∗(f)K(n)_*(f) is nilpotent for every n≥0n \ge 0. This is a form of the nilpotence theorem.
  2. (Periodicity) If XX has type n≥1n \ge 1, there is a map v ⁣:ΣdX→Xv \colon \Sigma^d X \to X such that K(n)∗(v)K(n)_*(v) is an isomorphism and K(m)∗(v)K(m)_*(v) is nilpotent for m≠nm \ne n.
  3. (Thick subcategories) Let 𝒞n\mathcal{C}_n be the category of finite pp-local spectra of type at least nn. Every thick subcategory of 𝒞0\mathcal{C}_0 is either some 𝒞n\mathcal{C}_n or the zero subcategory.
  4. (Smash product) For every spectrum XX, the natural map X∧LnS→LnXX \wedge L_n S \to L_n X is an equivalence, where SS is the pp-local sphere spectrum.
  5. (Chromatic convergence) For every finite pp-local spectrum XX, the map X→holim⁡nLnXX \to \operatorname{holim}_n L_n X is an equivalence.

Remarks

Ravenel posed these conjectures in 1984, together with the telescope conjecture. Devinatz, Hopkins and Smith proved the nilpotence theorem, and Hopkins and Smith deduced the periodicity and thick subcategory theorems from it. Hopkins and Ravenel proved the smash product and chromatic convergence theorems. The telescope conjecture is the exception: it holds at heights 00 and 11 but fails at every height n≥2n \ge 2.

At work: the sphere has type 00, and the mod pp Moore spectrum has type 11. For pp odd, the periodicity theorem is realised by Adams' map v1 ⁣:Σ2p−2S/p→S/pv_1 \colon \Sigma^{2p-2} S/p \to S/p, whose iterates give infinite families in the stable homotopy groups of spheres.

Going deeper

For a student

The thick subcategory theorem lets one prove a property for all finite spectra of type at least nn by checking it on a single example. The periodicity theorem produces the vnv_n-periodic families in the homotopy of spheres that chromatic homotopy theory studies. The smash product theorem says that LnL_n is a smashing localization, so it is determined by LnSL_n S. Chromatic convergence says that nothing is lost by studying a finite spectrum layer by layer.

Reading path

To understand this page from the ground up, read these 9 pages in order. The foundations come first.

Show the path as a graph
Each page uses the pages above it. The colour of the bar on a box shows how strong the evidence is, and the box also gives it as text. The list has the same pages.
  • no evidence level
  1. Chromatic homotopy theory concept
  2. Complex cobordism concept
  3. Prime number concept
  4. Ring spectrum concept
  5. Spectrum concept
  6. Stable homotopy groups of spheres concept
  7. Nishida nilpotence theorem statement
  8. Nilpotence theorem statement
  9. Ravenel conjectures statement

Where this leads

1 page builds on this one.

Further reading

  1. Web https://en.wikipedia.org/wiki/Ravenel's_conjectures
About this page
TagB8XP2K7RS1
URIm2://B8XP2K7RS1
Kindstatement, theorem
WritingW0 stub
MSC55P42, 55Q51, 55P60
StatusThis copy of the site has no build data. Run m2 status B8XP2K7RS1.
AboutChromatic homotopy theory
UsesChromatic homotopy theory, Spectrum, Nilpotence theorem, Prime number
Same as
Changed2 November 2026

Markdown · JSON · Edit on GitHub

What this page needs for W1

  • an inventory row: the row of the inventory that the node accounts for (0 of 1)
  • a source with a locator (0 of 1)

The writing levels say how complete the text of a page is. They do not measure its truth.

What links here

Used by