Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Overview of the CLEF--2021 CheckThat! Lab on Detecting Check-Worthy
  Claims, Previously Fact-Checked Claims, and Fake News   We describe the fourth edition of the CheckThat! Lab, part of the 2021
Conference and Labs of the Evaluation Forum (CLEF). The lab evaluates
technology supporting tasks related to factuality, and covers Arabic,
Bulgarian, English, Spanish, and Turkish. Task 1 asks to predict which posts in
a Twitter stream are worth fact-checking, focusing on COVID-19 and politics (in
all five languages). Task 2 asks to determine whether a claim in a tweet can be
verified using a set of previously fact-checked claims (in Arabic and English).
Task 3 asks to predict the veracity of a news article and its topical domain
(in English). The evaluation is based on mean average precision or precision at
rank k for the ranking tasks, and macro-F1 for the classification tasks. This
was the most popular CLEF-2021 lab in terms of team registrations: 132 teams.
Nearly one-third of them participated: 15, 5, and 25 teams submitted official
runs for tasks 1, 2, and 3, respectively.

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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-lat
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The categories of this paper are: funct-an
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The categories of this paper are: physics
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph