Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the number of coverings of the sphere ramified over given points   We present the generating function for the numbers of isomorphism classes of
coverings of the two-dimensional sphere by the genus $g$ compact oriented
surface not ramified outside of a given set of $m+1$ points in the target,
fixed ramification type over one point, and arbitrary ramification types over
the remaining $m$ points. We present the genus expansion of this generating
function and prove, that the generating function of coverings of genus $0$
satisfies some system of differential equations. We show that this generating
function is a specialization of the function from paper \cite{GJ} and,
therefore, satisfies the KP-hierarchy.

18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg