SEMINAR: Groups and Combinatorics Seminar, Groups and first-order logic

André Nies (University of Auckland)

will speak on

Groups and first-order logic

at 3pm Friday January the 31st in Blakers Lecture Theatre.

Abstract :

We study the expressive power of first-order logic for groups. A finitely generated group is called quasi-finitely axiomatizable if a single sentence characterizes it within the class of finitely generated groups. I showed in 2005 that, for instance, the Heisenberg group is quasi-finitely axiomatizable. Recent work of Lasserre provides new examples, such as the Thompson groups.

A group is homogeneous if the orbit of every tuple under the action of automorphisms is described by its first-order properties. I proved (J. Algebra, 2003) that the free group F_2 has this property. Recent work of Perrin and Sklinos (Duke Math. J. 2013) extends this to F_n for larger n.