Remove the dependence on the number of distances in the finite-field subdivision threshold

Establish that the conclusions of Theorem 1.4 hold with the size threshold C=O(q^{(d+1)/2}), independently of the cardinality |R| of the set of permitted nonzero distances, for every subset E\subseteq\mathbb{F}_q^d and every R-distance subdivision of a complete graph satisfying the theorem’s distance, dimension, and spanning conditions.

Background

Theorem \ref{th:ffApplicationSmalld0} proves that a sufficiently large subset E of \mathbb{F}_qd contains every R-distance subdivision of a complete graph whose branch vertices are separated by a prescribed logarithmic distance. Its sufficient threshold is C=72|R|{1/2}q{(d+1)/2}, so allowing more possible edge distances increases the required size of E.

The paper notes that the dependence on the number of distances is best possible for the general jumbled-family theorem but conjectures that it is not necessary in this finite-field distance-graph application. The stated conjecture seeks the sharper threshold C=O(q{(d+1)/2}), matching the single-distance scale and removing the factor involving |R|.

References

The conclusion of Theorem \ref{th:ffApplicationSmalld0} holds for C = O(q{(d+1)/2}).

Embedding edge-colored graphs in expanders with roll-back  (2501.14286 - Lund et al., 24 Jan 2025) in Conjecture immediately following the proof of Theorem \ref{th:ffApplicationSmalld0}, Section 1.3, “Embedding distance graphs into subsets of finite vector spaces”