Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Counterexamples to $ C^{\infty} $ well posedness for some hyperbolic
  operators with triple characteristics   In this paper we prove that for a class of non-effectively hyperbolic
operators with smooth triple characteristics the Cauchy problem is well posed
in the Gevrey 2 class, beyond the generic Gevrey class $ 3/2 $ (see e.g.
\cite{Bro}). Moreover we show that this value is optimal.

37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th