Joints of Varieties
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39_2022_Article_597.pdf
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Author(s)
Tidor, Jonathan
Yu, Hung-Hsun H.
Zhao, Yufei
Date Issued
April 2022
Journal
Geometric and Functional Analysis
Publisher
Springer International Publishing
Citation
Tidor, Jonathan, Yu, Hung-Hsun H. and Zhao, Yufei. 2022. "Joints of Varieties."
Version
Final published version
Abstract
Abstract
We generalize the Guth–Katz joints theorem from lines to varieties. A special case says that N planes (2-flats) in 6 dimensions (over any field) have
$$O(N^{3/2})$$
O
(
N
3
/
2
)
joints, where a joint is a point contained in a triple of these planes not all lying in some hyperplane. More generally, we prove the same bound when the set of N planes is replaced by a set of 2-dimensional algebraic varieties of total degree N, and a joint is a point that is regular for three varieties whose tangent planes at that point are not all contained in some hyperplane. Our most general result gives upper bounds, tight up to constant factors, for joints with multiplicities for several sets of varieties of arbitrary dimensions (known as Carbery’s conjecture). Our main innovation is a new way to extend the polynomial method to higher dimensional objects, relating the degree of a polynomial and its orders of vanishing on a given set of points on a variety.
MIT Department
Massachusetts Institute of Technology. Department of Mathematics
Terms of Use
Creative Commons Attribution
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1007/s00039-022-00597-5
