nLab
nilpotence theorem

Contents

Context

Higher linear algebra

homotopy theory, (∞,1)-category theory, homotopy type theory

flavors: stable, equivariant, rational, p-adic, proper, geometric, cohesive, directed

models: topological, simplicial, localic, …

see also algebraic topology

Introductions

Definitions

Paths and cylinders

Homotopy groups

Basic facts

Theorems

Contents

Idea

A fundamental statement in stable homotopy theory/higher algebra/chromatic homotopy theory.

Statement

For any ring spectrum RR the kernel of the canonical morphism

π RMU (R) \pi_\bullet R \longrightarrow MU_\bullet(R)

to the MU-homology of RR consists of nilpotent elements.

This is due to Devinatz-Hopkins-Smith 88 See Lurie 10, theorem 3

Special cases

The Nishida nilpotence theorem (Nishida 73) is the special case for the sphere spectrum, saying that all positive-degree elements in the stable homotopy groups of spheres are nilpotent.

This is indeed a special case. The MU-homology of the sphere spectrum is the Lazard ring and hence is torsion-free, whereas all positive-degree elements of the stable homotopy ring are torsion by the Serre finiteness theorem and therefore belong to the aforementioned kernel.

Consequences

Relation with \infty-fields

The nilpotence theorem implies that every ∞-field is an ∞-module over the Morava K-theory spectrum K(n)K(n), for some nn. See at ∞-field.

References

Last revised on July 21, 2020 at 05:43:37. See the history of this page for a list of all contributions to it.