Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Decomposability of quotients by complex conjugation for rational and
  Enriques surfaces   The quotients $Y=X/conj$ by the complex conjugation $conj\: X\to X$ for
complex rational and Enriques surfaces $X$ defined over $\R$ are shown to be
diffeomorphic to connected sums of $\barCP2$, whenever $Y$ are simply
connected.

15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th