Solution (source code)

= Solution
{c}

Use the <symmetric group> $S_3$, composing <permutations> from right to left. Set $x=(12)$ and $y=(23)$. Each is a <transposition>, so $x^3=x$ and $y^3=y$, whereas $xy=(123)$ has <order of a group element> three. Consequently
$$
T(xy)=(123)^3=e,\qquad T(x)T(y)=(12)(23)=(123)\ne e.
$$
Thus the cubing map on $S_3$ is not a <group homomorphism>.