The additive group of the rationals does not have an automatic presentation
arXiv:0905.1505
Abstract
We prove that the additive group of the rationals does not have an automatic presentation. The proof also applies to certain other abelian groups, for example, torsion-free groups that are -divisible for infinitely many primes , or . The proof is combinatorial and uses most notably Freiman's theorem on sets with small doubling.
11 pages