Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coupling the Dirac and Einstein equations through geometry   We show that the exterior algebra bundle over a curved spacetime can be used
as framework in which both the Dirac and the Einstein equations can be
obtained. These equations and their coupling follow from the variational
principle applied to a Lagrangian constructed from natural geometric
invariants. We also briefly indicate how other forces can potentially be
incorporated within this geometric framework.

13
The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc