English

On the linear independence of values of $G$-functions

Number Theory 2021-05-18 v1

Abstract

We consider a GG-function F(z)=k=0AkzkK[[z]]F(z)=\sum_{k=0}^{\infty} A_k z^k \in \mathbb{K}[[z]], where K\mathbb{K} is a number field, of radius of convergence RR and annihilated by the GG-operator LK(z)[d/dz]L \in \mathbb{K}(z)[\mathrm{d}/\mathrm{d}z], and a parameter βQZ0\beta \in \mathbb{Q} \setminus \mathbb{Z}_{\leqslant 0}. We define a family of GG-functions Fβ,n[s](z)=k=0Ak(k+β+n)szk+nF_{\beta,n}^{[s]}(z)=\sum_{k=0}^{\infty} \frac{A_k}{(k+\beta+n)^s} z^{k+n} indexed by the integers ss and nn. Fix αKD(0,R)\alpha \in \mathbb{K}^* \cap D(0,R). Let Φα,β,S\Phi_{\alpha,\beta,S} be the K\mathbb{K}-vector space generated by the values Fβ,n[s](α)F_{\beta,n}^{[s]}(\alpha), nNn \in \mathbb{N}, 0sS0 \leqslant s \leqslant S. We show that there exist some positive constants uK,F,βu_{\mathbb{K},F,\beta} and vF,βv_{F,\beta} such that uK,F,βlog(S)dimKΦα,β,SvF,βSu_{\mathbb{K},F,\beta} \log(S) \leqslant \dim_{\mathbb{K}} \Phi_{\alpha,\beta,S} \leqslant v_{F,\beta} S. This generalizes a previous theorem of Fischler and Rivoal (2017), which is the case β=0\beta=0. Our proof is an adaptation of their article "Linear independence of values of GG-functions'' ([FR]), making use of the Andr\'e-Chudnovsky-Katz Theorem on the structure of the GG-operators and of the saddle point method.

Keywords

Cite

@article{arxiv.2105.07683,
  title  = {On the linear independence of values of $G$-functions},
  author = {Gabriel Lepetit},
  journal= {arXiv preprint arXiv:2105.07683},
  year   = {2021}
}