Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Differentially Private Release of Public Transport Data: The Opal Use
  Case   This document describes the application of a differentially private algorithm
to release public transport usage data from Transport for New South Wales
(TfNSW), Australia. The data consists of two separate weeks of "tap-on/tap-off"
data of individuals who used any of the four different modes of public
transport from TfNSW: buses, light rail, train and ferries. These taps are
recorded through the smart ticketing system, known as Opal, available in the
state of New South Wales, Australia.

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The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex
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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: math-ph