This is the Peterson graph.  10 nodes, but best path back to start has
length 11.

(A B CONNECTED)
(B A CONNECTED)
(A C CONNECTED)
(C A CONNECTED)
(A I CONNECTED)
(I A CONNECTED)
(B F CONNECTED)
(F B CONNECTED)
(B H CONNECTED)
(H B CONNECTED)
(C D CONNECTED)
(D C CONNECTED)
(C E CONNECTED)
(E C CONNECTED)
(D H CONNECTED)
(H D CONNECTED)
(D J CONNECTED)
(J D CONNECTED)
(E F CONNECTED)
(F E CONNECTED)
(E G CONNECTED)
(G E CONNECTED)
(F J CONNECTED)
(J F CONNECTED)
(G H CONNECTED)
(H G CONNECTED)
(G I CONNECTED)
(I G CONNECTED)
(I J CONNECTED)
(J I CONNECTED)



(preconds (at truck A))

(effects (at truck A) (visited A) (visited B) (visited C) (visited D) 
(visited E) (visited F) (visited G) (visited H) (visited I) (visited J))