Lower Bounds on the Growth of Grigorchuk's Torsion Group

Abstract

In 1980 Rostislav Grigorchuk constructed a group $G$ of intermediate growth, and later obtained the following estimates on its growth $\gamma$: $e^{\sqrt{n}}\precsim\gamma(n)\precsim e^{n^\beta},$ where $\beta=\log_{32}(31)\approx0.991$. He conjectured that the lower bound is actually tight. In this paper we improve the lower bound to $e^{n^\alpha}\precsim\gamma(n),$ where $\alpha\approx0.5157$, with the aid of a computer. This disproves the conjecture that the lower bound be tight.