= Solution
Write $F,R,C$ for the three item constants, $E,W$ for the banks, $L,U,M$ for the corrected load, unload and move actions, and $K_s$ for $\mathrm{Check}(s,p_F,p_R,p_C)$ instantiated with the items' actual current locations. A fully executable plan in the <STRIPS> model of part (g) is
$$
\begin{aligned}
&L(R,E),\ K_E,\ M(E,W),\ U(R,W),\\
&K_W,\ M(W,E),\\
&L(F,E),\ K_E,\ M(E,W),\ U(F,W),\\
&L(R,W),\ K_W,\ M(W,E),\ U(R,E),\\
&L(C,E),\ K_E,\ M(E,W),\ U(C,W),\\
&K_W,\ M(W,E),\\
&L(R,E),\ K_E,\ M(E,W),\ U(R,W).
\end{aligned}
$$
Thus the seven crossings carry \b[rabbit west, nothing east, fox west, rabbit east, carrot west, nothing east, rabbit west].
Immediately before those crossings, the items left on the departure bank are respectively $\{F,C\},\{R\},\{C\},\{F\},\{R\},\{F,C\},\varnothing$. None contains an incompatible pair, so each displayed $K_s$ has its safety <preconditions>. Each loaded crossing carries exactly one item, and all three finish west.
Back to article page
