Solution (source code)

= Solution

The <Alexander numbering> of the three lobe regions is one and that of the central region is two, relative to the unbounded region numbered zero. Equivalently, abelianizing the three relators gives
$$
A-D+B=0,
\qquad B-D+C=0,
\qquad C-D+A=0.
$$
Thus $A=B=C$ and $D=2A$. The class $A$ is the positively oriented <meridian of a knot>, so
$$
\boxed{\phi(a)=\phi(b)=\phi(c)=\phi(\mu),
\qquad \phi(d)=2\phi(\mu).}
$$