Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exactness of Second Order Ordinary Differential Equations and
  Integrating Factors   A new problem is studied, the concept of exactness of a second order
nonlinear ordinary differential equations is established. A method is
constructed to reduce this class into a first order equations. If the second
order equation is not exact we introduce, under certain conditions, an
integrating factor that transform it to an exact one.

17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga