Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An index for two-dimensional SPT states   We define an index for 2d $G$-invariant invertible states of bosonic lattice
systems in the thermodynamic limit for a finite symmetry group $G$. We show
that this index is an invariant of SPT phase.

37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: eess
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
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The categories of this paper are: econ
9
The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: solv-int
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The categories of this paper are: stat