“…We construct the graph G ′ from G, see Figure 2. It is not difficult to verify that (V (1,1) , V (1,2) , V (2,3) , V (3,4) , V (4,2) , V (2,5) , V (5,5) ) is the shortest V (1,1) -V (5,5) path in G ′ , whose cost is ǫ. However this V (1,1) -V (5,5) path does not correspond to a path in G, but to a walk.…”