{ "id": "2411.04959", "version": "v1", "published": "2024-11-07T18:37:13.000Z", "updated": "2024-11-07T18:37:13.000Z", "title": "Bounding the dimension of exceptional sets for orthogonal projections", "authors": [ "Peter Cholak", "Marianna Csornyei", "Neil Lutz", "Patrick Lutz", "Elvira Mayordomo", "D. M. Stull" ], "categories": [ "math.CA" ], "abstract": "It is well known that if $A\\subseteq\\R^n$ is an analytic set of Hausdorff dimension $a$, then $\\dim_H(\\pi_VA)=\\min\\{a,k\\}$ for a.e. $V\\in G(n,k)$, where $\\pi_V$ is the orthogonal projection of $A$ onto $V$. In this paper we study how large the exceptional set \\begin{center} $\\{V\\in G(n,k) \\mid \\dim_H(\\pi_V A) < s\\}$ \\end{center} can be for a given $s\\le\\min\\{a,k\\}.$ We improve previously known estimates on the dimension of the exceptional set, and we show that our estimates are sharp for $k=1$ and for $k=n-1$.", "revisions": [ { "version": "v1", "updated": "2024-11-07T18:37:13.000Z" } ], "analyses": { "keywords": [ "exceptional set", "orthogonal projection", "hausdorff dimension", "analytic set" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }