Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The GraviGUT Algebra Is not a Subalgebra of $E_8$, but $E_8$ Does
  Contain an Extended GraviGUT Algebra   The (real) GraviGUT algebra is an extension of the $\mathfrak{spin}(11,3)$
algebra by a $64$-dimensional Lie algebra, but there is some ambiguity in the
literature about its definition. Recently, Lisi constructed an embedding of the
GraviGUT algebra into the quaternionic real form of $E_8$. We clarify the
definition, showing that there is only one possibility, and then prove that the
GraviGUT algebra cannot be embedded into any real form of $E_8$. We then modify
Lisi's construction to create true Lie algebra embeddings of the extended
GraviGUT algebra into $E_8$. We classify these embeddings up to inner
automorphism.

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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: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: astro-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: quant-ph