Skip to main content
3 of 4
Added another extra relevant question related to the rational cohomology.
user127776
  • 5.9k
  • 2
  • 9
  • 24

Singular cohomology of fields

Let's define the singular cohomologies of function fields of complex varieties, as the direct limit of the singular cohomologies of Zariski opens of the variety with analytic topology. So for a complex variety $X$ where its function field is $F(X)$, we have defined $H^i(F(X), \mathbb{Z})$. Similarly let's define singular cohomology of the algebraic closure $\overline{F(X)}$, as the direct limit of singular cohomology of finite extensions of $F(X)$. Now my question is: Is the cohomology ring of $\overline{F(X)}$ generated by the first cohomology group and cup product?

Is this true rationally when considering the generic point of the variety? (is $H^i(F(X), \mathbb{Q})$ generated by $H^1$?). Are there any examples that the cohomology ring of the generic point has been calculated (other than curves).

Edit: As a motivation I wanted to add this: this is true if we consider cohomology with finite coefficients and it follows from Bloch-Kato.

user127776
  • 5.9k
  • 2
  • 9
  • 24