Skip to main content

Questions tagged [cohomological-dimension]

6 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
12 votes
0 answers
891 views

What is the intuition for $\mathbb{Q}^{ab}$ having cohomological dimension $1$?

I frequently talk to people who think of finite fields as arithmetic analogs of punctured discs. This makes some sense: the absolute Galois group of a finite field is the profinite completion of $\...
4 votes
0 answers
215 views

cohomological dimension for coarser/finer topologies

Given a sheaf $\mathcal{F}$ with respect to some Grothendieck topology, is the cohomological dimension for this sheaf less than or equal to the cohomological dimension of a finer topology? Example: $...
user12832's user avatar
  • 417
2 votes
0 answers
95 views

Cohomological dimension of functors from fields to vector spaces

Let $K$ be an algebraically closed field. Denote by $\mathcal F_d$ the category of extensions $K\to F$ of transcendent degree $d$.(Objects are pairs $F,j$ consisting of a field $F$ and the embedding $...
Galois group's user avatar
2 votes
0 answers
600 views

cohomological dimension of the push-forward functor

Let $\ell$ be a prime number and let $f:X \to Y$ be a morphism of schemes of finite type over the complex numbers (or a regular scheme of dimension at most 1, in which $\ell$ is invertible). How to ...
shenghao's user avatar
  • 4,265
1 vote
0 answers
223 views

Cohomological dimension of continuous étale cohomology of finitely generated fields

Given a finitely generated field $F$ with prime field $k$, we assume $k$ is finite, of characteristic $p$. Fix a prime $\ell$ invertible in $k$. In the discussion right after [K, Lemma 2.3], the ...
user127776's user avatar
  • 5,901
1 vote
0 answers
288 views

Rational cohomological dimension of the lattices in $SL_n(\mathbb{Q}_p)$

What is the rational cohomological dimension of the lattices in $SL_n(\mathbb{Q}_p)$, where $n\geq 3$ ? A reference would be appreciated. For the definition of "cohomological dimension of a group ...
Kajal Das's user avatar
  • 105