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arXiv · 2506.14031

Left-invariant ${\rm G}_2^*$-structures of type III

Viviana del Barco·Ana Cristina Ferreira·Ines Kath
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Abstract

We investigate left-invariant ${\rm G}_2^*$-structures on 7-dimensional Lie groups, focusing on those whose holonomy algebras are indecomposable and of type III, the latter meaning that the socle of the holonomy representation is maximal. Building on the classification of indecomposable holonomy algebras contained in $\mathfrak g_2^*$, we determine which ones arise as infinitesimal holonomy algebras of type III for left-invariant ${\rm G}_2^*$-structures. Our main result shows that only abelian subalgebras occur, and these are necessarily of dimension two or three. Moreover, we provide explicit Lie groups with left-invariant ${\rm G}_2^*$-structures realizing these abelian holonomies.

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Viviana del Barco, Ana Cristina Ferreira, Ines Kath. 2025-06-16. Left-invariant ${\rm G}_2^*$-structures of type III. https://arxiv.org/abs/2506.14031

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