Mathematics – Group Theory
Scientific paper
2002-04-07
Mathematics
Group Theory
19 pages, 8 PostScript figures
Scientific paper
This note describes the first example of a group that is amenable, but cannot be obtained by subgroups, quotients, extensions and direct limits from the class of groups locally of subexponential growth. It has a balanced presentation \[\Delta = < b,t|[b,t^2]b^{-1},[[[b,t^{-1}],b],b]>.\] I show that it acts transitively on a 3-regular tree, and that $\Gamma=< b,b^{t^{-1}}$ stabilizes a vertex and acts by restriction on a binary rooted tree. $\Gamma$ is a "fractal group", generated by a 3-state automaton, and is a discrete analogue of the monodromy action of iterates of f(z)=z^2-1 on associated coverings of the Riemann sphere. $\Delta$ shares many properties with the Thompson group $F$. The proof of the main result (amenability of $\Delta$) is incomplete in the present form; please refer to the paper arxiv.org/math.GR/0305262, joint with Balint Virag, for a complete proof.
No associations
LandOfFree
Amenability of groups acting on trees does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Amenability of groups acting on trees, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Amenability of groups acting on trees will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-595263