Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: HI in Early-Type Galaxies   We briefly discuss the main differences between the HI properties of luminous
and low-luminosity early-type galaxies. In luminous early-type galaxies the HI
is often irregularly distributed, but in a few cases regular HI disks, of low
surface density, are seen. In low-luminosity galaxies, the HI is more often in
a disk with high central surface densities. This suggests a different evolution
of the gas in these two groups of galaxies.

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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph