Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Approximating classifying spaces by smooth projective varieties   We prove that for every reductive algebraic group $H$ with centre of positive
dimension and every integer $K$ there is a smooth and projective variety $X$
and an algebraic $H$-torsor $P \to X$ such that the classifying map $X \to
\Bclass H$ induces an isomorphism in cohomology in degrees $\le K$. This is
then applied to show that if $G$ is a connected non-special group there is a
$G$-torsor $P \to X$ for which we do not have $[P]=[G][X]$ in the (completion
of the) Grothendieck ring of varieties.

5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph