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arXiv · 1901.06665

On $\mathrm{G}_2$ and Sub-Riemannian Model Spaces of Step and Rank Three

Eirik Berge·Erlend Grong
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Abstract

We give the complete classification of all sub-Riemannian model spaces with both step and rank three. They will be divided into three families based on their nilpotentization. Each family will depend on a different number of parameters, making the result crucially different from the known case of step two model spaces. In particular, there are no nontrivial sub-Riemannian model spaces of step and rank three with free nilpotentization. We also realize both the compact real form $\mathfrak{g}_2^c$ and the split real form $\mathfrak{g}_2^s$ of the exceptional Lie algebra $\mathfrak{g}_2$ as isometry algebras of different model spaces.

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Eirik Berge, Erlend Grong. 2019-01-20. On $\mathrm{G}_2$ and Sub-Riemannian Model Spaces of Step and Rank Three. https://arxiv.org/abs/1901.06665

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