Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intersecting families of sets and permutations: a survey   A family $\mathcal{A}$ of sets is said to be \emph{$t$-intersecting} if any
two sets in $\mathcal{A}$ have at least $t$ common elements. A central problem
in extremal set theory is to determine the size or structure of a largest
$t$-intersecting sub-family of a given family $\mathcal{F}$. We give a survey
of known results, conjectures and open problems for various important families
$\mathcal{F}$, namely, power sets, levels of power sets, hereditary families,
families of signed sets, families of labeled sets, and families of
permutations. We also provide some extensions and consequences of known
results.

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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: astro-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org