Cayley graph of the fundamental group of the 2-torus

1.1k Views Asked by At

Does anybody knows some description or some good picture on the internet for the Cayley graph of the fundamental group of the 2-torus, when this is constructed by connected sum of two torus. I know, by van-Kampen theorem, this group is an product of two 2-free groups amalgamated by Z, but I really need to literally see that.

1

There are 1 best solutions below

4
On

It looks like this:

A closed orientable surface of genus $2$ admits a hyperbolic metric, so corresponds to some quotient of the hyperbolic plane $\mathbb{H}$. The action of the fundamental group on $\mathbb{H}$ can be used to draw a Cayley graph in $\mathbb{H}$. This is what this picture is depicting, in the Poincaré disk model of $\mathbb{H}$.