Irrationality exponent and rational approximations with prescribed growth
Abstract
Let be a real irrational number. We are interested in sequences of linear forms in 1 and , with integer coefficients, which tend to 0. Does such a sequence exist such that the linear forms are small (with given rate of decrease) and the coefficients have some given rate of growth? If these rates are essentially geometric, a necessary condition for such a sequence to exist is that the linear forms are not too small, a condition which can be expressed precisely using the irrationality exponent of . We prove that this condition is actually sufficient, even for arbitrary rates of growth and decrease. We also make some remarks and ask some questions about multivariate generalizations connected to Fischler-Zudilin's new proof of Nesterenko's linear independence criterion.
Cite
@article{arxiv.0910.4448,
title = {Irrationality exponent and rational approximations with prescribed growth},
author = {Stéphane Fischler and Tanguy Rivoal},
journal= {arXiv preprint arXiv:0910.4448},
year = {2012}
}
Comments
11 pages, to appear in Proc. Amer. Math. Soc