PSL(2,Z) as a non distorted subgroup of Thompson's group T

TL;DR

This paper characterizes PSL(2,Z) within Thompson's group T using reduced tree pair diagrams and piecewise linear maps, demonstrating that PSL(2,Z) is a non-distorted subgroup and identifying non-distorted free non-abelian subgroups.

Contribution

It constructs normal form tree pair diagrams for PSL(2,Z) elements and proves its non-distortion within T, revealing new subgroup structures.

Findings

PSL(2,Z) is a non-distorted subgroup of T

Constructed normal form tree pair diagrams for PSL(2,Z) elements

Identified non-distorted free non-abelian subgroups in T

Abstract

In this paper we characterize the elements of PSL(2,Z), as a subgroup of Thompson group T, in the language of reduced tree pair diagrams and in terms of piecewise linear maps as well. Actually, we construct the reduced tree pair diagram for every element of PSL(2,Z) in normal form. This allows us to estimate the length of the elements of PSL(2,Z) through the number of carets of their reduced tree pair diagrams and, as a consequence, to prove that PSL(2,Z) is a non distorted subgroup of T. In particular, we find non-distorted free non abelian subgroups of T.