Equality of rank-dimension and coarse dimension for quantifier-free types

Let (F,Frob)S(F,\operatorname{Frob})\in\mathcal{S}. For any countable set AFA\subseteq F and complete quantifier-free Lσ\mathcal{L}_\sigma-type p(x)Snqf(A)p(x)\in S^{qf}_n(A), the two dimensions are defined by the rank-dimension dimrk\operatorname{dim}_{rk} and the coarse dimension δF\pmb{\delta}_F. Equality conjecture. The following holds

δF(p(x))=dimrk(p(x)).\pmb{\delta}_F(p(x))=\operatorname{dim}_{rk}(p(x)).

The conjecture asks whether the two integer-valued additive dimensions coincide on quantifier-free types. The inequality δFdimrk\pmb{\delta}_F\leq\operatorname{dim}_{rk} is established in the paper, while the reverse inequality is not known even in this quantifier-free setting; a positive answer would allow the equivalence to be extended to existential types.

Sources & referencesView supporting material

Primary source

Tingxiang Zou, “Pseudofinite difference fields and counting dimensions”, arXiv:1806.10026 (2020).

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.