Chernikov's VC-density conjecture for NIP structures

Let (M;)(M;\ldots) be an NIP structure, and let S={Sb:bY}\mathcal{S}=\{S_b:b\in Y\} be a definable set system with YMnY\subseteq M^n. Define its VC-density by

vc(S)=lim suptlogπS(t)logt.\operatorname{vc}(\mathcal{S})=\limsup_{t\to\infty}\frac{\log\pi_{\mathcal{S}}(t)}{\log t}.

Chernikov's VC-density conjecture. The following assertions hold:

  1. vc(S)\operatorname{vc}(\mathcal{S}) is rational.
  2. If MM is o-minimal, there is a finite set Δ=Δ(n)[0,n]Q\Delta=\Delta(n)\subseteq[0,n]\cap\mathbb{Q} such that vc(S)Δ\operatorname{vc}(\mathcal{S})\in\Delta.
  3. If MM is o-minimal and weakly locally modular, then vc(S){0,1,,n}\operatorname{vc}(\mathcal{S})\in\{0,1,\ldots,n\}.

These statements formalize the proposed distinction between field-like and module-like structures through shatter-function growth. The source attributes this conjecture to Chernikov; its resolution status is not specified in the supplied text.

Sources & referencesView supporting material

Primary source

Abdul Basit and Chieu-Minh Tran, “On the shatter function of semilinear set systems”, arXiv:2501.10032 (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.