Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Algebraic Structure of the Holomorphic Anomaly for N=2
  Topological Strings   The special geometry ($(t,{\bar t})$-equations) for twisted $N=2$ strings are
derived as consistency conditions of a new contact term algebra. The dilaton
appears in the contact terms of topological and antitopological operators. The
holomorphic anomaly, which can be interpreted as measuring the background
dependence, is obtained from the contact algebra relations.

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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: math
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The categories of this paper are: comp-gas
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The categories of this paper are: atom-ph