Math 2.0

K-theory Higher algebraic K-theory Theorem

Bloch–Lichtenbaum spectral sequence

Builds on Motivic cohomologyFieldSpectral sequenceAlgebraic K-theory

Statement

Let FF be a field. Write CHj(F,m)CH^j(F, m) for the higher Chow groups of Spec⁡F\operatorname{Spec} F, so that CHj(F,m)=H2j−m(F,ℤ(j))CH^j(F, m) = H^{2j - m}(F, \Z(j)) is motivic cohomology. Write Kn(F)K_n(F) for the algebraic K-groups of FF. Then there is a strongly convergent spectral sequence E2p,q=CH−q(F,−p−q)⟹K−p−q(F).E_2^{p, q} = CH^{-q}(F, -p - q) \Longrightarrow K_{-p-q}(F).

Remarks

Bloch and Lichtenbaum built it from a tower of spectra made of K-theory of the algebraic simplices with supports on cycles in good position. For a field, CHj(F,m)=0CH^j(F, m) = 0 when j>mj > m, so the nonzero terms satisfy p≤0p \le 0 and q≤0q \le 0. The term E20,−n=CHn(F,n)≅KnM(F)E_2^{0, -n} = CH^n(F, n) \cong K^M_n(F) gives the edge map from Milnor K-theory to Quillen K-theory. Example: in total degree 11, the only nonzero term is E20,−1=CH1(F,1)≅F×E_2^{0,-1} = CH^1(F, 1) \cong F^\times, and the spectral sequence recovers K1(F)≅F×K_1(F) \cong F^\times. Rationally the spectral sequence degenerates at E2E_2.

Going deeper

For a student

This was the first motivic spectral sequence, and it was later extended from fields to all smooth varieties. It is the analogue for fields of the Atiyah–Hirzebruch spectral sequence in topology. Together with the comparison of motivic and étale cohomology, it is a route from the Bloch–Kato conjecture to the Quillen–Lichtenbaum conjecture.

Reading path

To understand this page from the ground up, read these 5 pages in order. The foundations come first.

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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.
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  1. Algebraic K-theory concept
  2. Field concept
  3. Motivic cohomology concept
  4. Spectral sequence concept
  5. Bloch–Lichtenbaum spectral sequence statement

Where this leads

2 pages build on this one.

Further reading

  1. Web https://en.wikipedia.org/wiki/Motivic_cohomology
About this page
Tag6E0DCB1NF1
URIm2://6E0DCB1NF1
Kindstatement, theorem
WritingW0 stub
MSC19E15, 19D45, 14C25
StatusThis copy of the site has no build data. Run m2 status 6E0DCB1NF1.
AboutMotivic cohomology, Algebraic K-theory
UsesMotivic cohomology, Field, Spectral sequence, Algebraic K-theory
Changed3 November 2026

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