  For semigroup $S$, a commutative congruence $\sigma_{orient}$ on $S$ and a
subsemigroup Orientable($S$) of $S$ were introduced in "Two cancellative
commutative congruences and group diagrams", Semigroup Forum (2011) 82:
338-353. Here we demonstrate that when the semigroup is in fact a group $G$,
then Orientable($G$) is the commutator subgroup $[G,G]$ and $ G /
\sigma_{orient}$ is the abelian quotient group $G / [G,G]$.
