English

Lusin Approximation and Horizontal Curves in Carnot Groups

Metric Geometry 2015-11-26 v4

Abstract

We show that, given an absolutely continuous horizontal curve γ\gamma in the Heisenberg group, there is a C1C^1 horizontal curve Γ\Gamma such that Γ=γ\Gamma=\gamma and Γ=γ\Gamma'=\gamma' outside a set of small measure. Conversely, we construct an absolutely continuous horizontal curve in the Engel group with no C1C^1 horizontal approximation.

Keywords

Cite

@article{arxiv.1412.2531,
  title  = {Lusin Approximation and Horizontal Curves in Carnot Groups},
  author = {Gareth Speight},
  journal= {arXiv preprint arXiv:1412.2531},
  year   = {2015}
}

Comments

21 pages. Corrected a technical error in the argument for the Heisenberg group and added previously omitted proofs. Improved the exposition and corrected typos as suggested by referees. To appear in Revista Matematica Iberoamericana

R2 v1 2026-06-22T07:23:26.606Z