The discretized Kakeya conjecture

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Let T\mathbb{T} be a set of δ\delta-tubes in Rn\mathbb{R}^n pointing in δ\delta-separated directions, and write ⪆\gtrapprox for an inequality up to factors of δ−ε\delta^{-\varepsilon} for every ε>0\varepsilon>0.

Discretized Kakeya conjecture. The following two assertions should hold:

(A)

∣⋃T∈TT∣⪆∑T∈T∣T∣.\left|\bigcup_{T\in\mathbb{T}}T\right|\gtrapprox\sum_{T\in\mathbb{T}}|T|.

(B) If Y(T)⊂TY(T)\subset T is measurable and ∣Y(T)∣≥(log⁡1/δ)−1∣T∣|Y(T)|\geq(\log 1/\delta)^{-1}|T| for every T∈TT\in\mathbb{T}, then

∣⋃T∈TT∣⪆∑T∈T∣T∣.\left|\bigcup_{T\in\mathbb{T}}T\right|\gtrapprox\sum_{T\in\mathbb{T}}|T|.

Assertion (A) implies the Minkowski-dimension part of the Kakeya set conjecture, while (B) implies the Hausdorff-dimension part. The source presents these as conjectural discretized analogues; no resolution status is supplied.

References

Primary source

Joshua Zahl, “A Survey of the Kakeya conjecture, 2000-2025”, arXiv:2512.09397 (2025).

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