Oberlin's restricted projection conjecture in three dimensions

About 1 year old · traced to

Let t∈[0,3]t\in[0,3] and let s∈[0,min⁡{t,1}]s\in\left[0,\min\{t,1\}\right]. For a Borel set A⊆R3A\subseteq\mathbb{R}^3 with dim⁡A=t\dim A=t, write ρθ(A)\rho_\theta(A) for its restricted projection at angle θ∈[0,2π)\theta\in[0,2\pi). Oberlin's restricted projection conjecture. One should have

dim⁡{θ∈[0,2π):dim⁡ρθ(A)<s}≤max⁡{3s2−t2,0}.\dim\left\{\theta\in[0,2\pi):\dim\rho_\theta(A)<s\right\}\leq\max\left\{\frac{3s}{2}-\frac{t}{2},0\right\}.

The conjecture is an analogue of Oberlin's planar projection conjecture for restricted projections in R3\mathbb{R}^3. It is known when t≤1t\leq1 and s=ts=t, and when t≥1t\geq1 and s=1s=1; the case s=t/3s=t/3 is the paper's preceding proposition. The intermediate cases remain open.

References

Primary source

John Green, Terence L. J. Harris, Yumeng Ou, Kevin Ren and Sarah Tammen, “Incidence bounds related to circular Furstenberg sets”, arXiv:2502.10686 (2025).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.