Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Universal and ultrahomogeneous abelian Polish metric group   We use Fra\" iss\' e theoretic methods to construct a universal and
ultrahomogeneous abelian separable metric group. We show that such a group is a
universal abelian Polish group, thus we provide another proof of a result
already discovered by Shkarin. We then construct universal and ultrahomogeneous
abelian periodic metric groups with bounded exponents; it follows that these
groups are also universal objects for the corresponding classes of abelian
Polish groups.

20
The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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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: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int