Texas A&M University, Department of
Mathematics, 216 Milner Hall, 7th of December 2005, 3:00-3:50
Groups and Dynamics Seminar
On geodesics and
dead ends in Grigorchuk group
Zoran Sunik of Texas A&M University
We present our current knowledge of the set L of geodesics in the
Cayley graph of the first Grigorchuk group G. In particular, we present
an indexed language that describes all the geodesics coming from
geodesics in Schreier graphs. This language, as well as the full
language of geodesics L, is closed under the endomorphism used in the
Lysionok presentation of G. Further, we show that half of a Lysionok
word is always a geodesic representing a dead end. We present some
conjectures on flat tetrahedra and dead ends in the Cayley graph. Some
of the difficulties in dealing with the set of geodesics L in G is
apparent from the fact that L does not contain any infinite
context-free subset.