The group of strong automorphisms of the differential field of transseries

Abstract

We describe the group of strongly additive automorphisms of the differential field $\mathbb{T}$ of transseries as a non-trivial semidirect product. We show that this group is torsion-free and has trivial center, and that many naturally arising differential subfields of $\mathbb{T}$ are definably closed in $\mathbb{T}$.

arXiv comment59 pp