Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Self-Compression of High-Intensity Femtosecond Laser Pulses in Low
  Dispersion Regime   Self-compression of femtosecond laser pulses and more than an order of
magnitude increase of the peak intensity is found in a positive dispersion
medium in low dispersion regime based on the (3+1)-dimensional nonlinear
Schr{\"o}dinger equation. A method of high-intensity femtosecond pulse
formation can be developed on that basis.

35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph