Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Combinatorial specifications for juxtapositions of permutation classes   We show that, given a suitable combinatorial specification for a permutation
class $\mathcal{C}$, one can obtain a specification for the juxtaposition (on
either side) of $\mathcal{C}$ with Av(21) or Av(12), and that if the
enumeration for $\mathcal{C}$ is given by a rational or algebraic generating
function, so is the enumeration for the juxtaposition. Furthermore this process
can be iterated, thereby providing an effective method to enumerate any
'skinny' $k\times 1$ grid class in which at most one cell is non-monotone, with
a guarantee on the nature of the enumeration given the nature of the
enumeration of the non-monotone cell.

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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ph
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The categories of this paper are: mtrl-th
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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: cmp-lg
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The categories of this paper are: supr-con
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The categories of this paper are: q-bio
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The categories of this paper are: atom-ph
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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: physics
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The categories of this paper are: eess
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas