2016/08/16 by Greenleaf, Allan, Iosevich, Alex, Liu, Bochen +1 · 1 citation
#Classical Analysis and ODEs (math.CA) #Combinatorics (math.CO) #FOS: Mathematics
paper · doi:10.48550/arxiv.1608.04777
We prove that if the Hausdorff dimension of E ⊂ \Bbb Rd, d ≥ 3, is greater than min \ (dk+1)/(k+1), (d+k)/(2) \, then the k+1 \choose 2-dimensional Lebesgue measure of Tk(E), the set of congruence classes of k-dimensional simplexes with vertices in E, is positive. This improves the best bounds previously known, decreasing the (d+k+1)/(2) threshold obtained in Erdoğan-Hart-Iosevich (2012) to (d+k)/(2) via a different and conceptually simpler method. We also give a simpler proof of the d-(d-1)/(2d) threshold for d-dimensional simplexes obtained in Greenleaf-Iosevich (2012), Grafakos-Greenleaf-Iosevich-Palsson (2015).