Projections of planar sets in well-separated directions
Classical Analysis and ODEs
2016-04-21 v5
Abstract
First, let be a set with , and write for the orthogonal projection of into the line spanned by . For , write where is the -covering number of the set . It is well-known -- and essentially due to R. Kaufman -- that . Using the polynomial method, I prove that I construct examples showing that the exponents in the bound are sharp for . The second theorem concerns projections of -Ahlfors-David regular sets. Let and be given. I prove that, for large enough, the finite set of unit vectors has the following property. If is non-empty and -Ahlfors-David regular with regularity constant at most , then for all small enough . In particular, for some .
Keywords
Cite
@article{arxiv.1504.07189,
title = {Projections of planar sets in well-separated directions},
author = {Tuomas Orponen},
journal= {arXiv preprint arXiv:1504.07189},
year = {2016}
}
Comments
20 pages, 3 figures. v5: Corrected typos and updated references. To appear in Adv. Math