Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scattering of Open and Closed Strings in 1+1 Dimensions   The ground ring structure of 1+1 dimensional string theory leads to an
infinite set of non linear recursion relations among the `bulk' scattering
amplitudes of open and closed tachyons on the disk, which fix them uniquely.
The relations are generated by the action of the ring on the tachyon modules;
associativity of this action determines all structure constants. This algebraic
structure may allow one to relate the continuum picture to a matrix model.

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The categories of this paper are: acc-phys
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
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The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: econ
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an