Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A simple proof of ill-posedness for incompressible Euler equations in
  critical Sobolev spaces   We provide a simple proof that the Cauchy problem for the incompressible
Euler equations in $\mathbb{R}^{d}$ with any $d\ge3$ is ill-posed in critical
Sobolev spaces, extending an earlier work of Bourgain and Li in the case $d =
3$. The ill-posedness is shown for certain critical Lorentz spaces as well.

5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int