English

Directional Pliability, Whitney Extension, and Lusin Approximation for Curves in Carnot Groups

Differential Geometry 2025-05-21 v1

Abstract

We show that, in arbitrary Carnot groups, pliability in a subset of directions is sufficient to guarantee the existence of a Whitney-type extension and a Lusin approximation for curves with tangent vectors in the same set of directions. We apply this to show that every horizontal curve in the Engel group must intersect a C1C^{1} horizontal curve in a set of positive measure.

Keywords

Cite

@article{arxiv.2505.14678,
  title  = {Directional Pliability, Whitney Extension, and Lusin Approximation for Curves in Carnot Groups},
  author = {Gareth Speight and Scott Zimmerman},
  journal= {arXiv preprint arXiv:2505.14678},
  year   = {2025}
}

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22 pages