Consider the space
Letand let a be a loop in
with base point
which goes clockwise once around the circle. Let the set of loops in
be labeled
For each
and
define
whereis the identity function.
Note thatif and only if
For
there is
such that
Thus there is an isomorphismbetween the quotient group
and
where
if
and
loop the same number of times in the same sense, given by h([n,a]) =n.
The groupis generated by the element