Non-Zariski-dense best-approximation conjecture

Let XX be a smooth, projective variety defined over a number field kk, let PX(k)P\in X(k), and let AA be an ample line bundle on XX. Let α(P,A)\alpha(P,A) denote the infimum of approximation constants of sequences of kk-rational points approaching PP, and let αess(P,A)\alpha_{ess}(P,A) denote the corresponding infimum over Zariski-dense sequences. For a subvariety i ⁣:VXi\colon V\hookrightarrow X, write α(P,AV):=α(P,iA)\alpha(P,A|_V):=\alpha(P,i^*A). Non-Zariski-dense best-approximation conjecture. If α(P,A)<\alpha(P,A)<\infty, then there is a sequence of best AA-approximations to PP that is not Zariski dense. Equivalently, there is a proper subvariety VV such that

α(P,AV)αess(P,A).\alpha(P,A|_V)\leq\alpha_{ess}(P,A).

This is a weaker higher-dimensional analogue of the curve conjecture: unlike for surfaces, the argument only guarantees a proper subvariety rather than a curve.

Sources & referencesView supporting material

Primary source

Brian Lehmann, David McKinnon and Matthew Satriano, “Approximating rational points on surfaces”, arXiv:2403.02480 (2024).

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.