Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Elementary doublets of bound states of the radial Dirac equation   For non-relativistic Schroedinger equations the lowering of their degree by
substitution Psi(r) \to F(r) =Psi'(r) /Psi(r) is known to facilitate our
understanding and use of their (incomplete, so called quasi-exact) solvability.
We show that and how the radial Dirac relativistic equation may quasi-exactly
be solved in similar spirit.

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The categories of this paper are: cmp-lg
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The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc