Packing dimension of vertical projections in the Heisenberg group
Classical Analysis and ODEs
2026-03-10 v10 Metric Geometry
Abstract
It is shown that if is a Borel subset of the first Heisenberg group, with Hausdorff dimension satisfying , then the packing dimensions of vertical projections of are almost surely not less than , where both packing and Hausdorff dimensions are defined with respect to the Kor\'anyi metric. For the Hausdorff dimension of the projections, a weaker almost sure lower bound is obtained which improves the known bound in the range . The bound is slightly larger than and behaves similarly near . Both proofs rely on a variable coefficient local smoothing inequality.
Keywords
Cite
@article{arxiv.2407.11475,
title = {Packing dimension of vertical projections in the Heisenberg group},
author = {Terence L. J. Harris},
journal= {arXiv preprint arXiv:2407.11475},
year = {2026}
}
Comments
34 pages. V8: Proof fixed by using packing instead of Hausdorff dimension. V10: Added partial result for Hausdorff dimension which restores result from V4 with small improvement