2 directTrain(forbach,saarbruecken).
3 directTrain(freyming,forbach).
4 directTrain(fahlquemont,stAvold).
5 directTrain(stAvold,forbach).
6 directTrain(saarbruecken,dudweiler).
7 directTrain(metz,fahlquemont).
8 directTrain(nancy,metz).
11 train(X,Y):-directTrain(X,Y).
12 train(X,Y):-directTrain(Y,X).
15 travelBetween(X,Y):- train(X,Y).
16 travelBetween(X,Y):- train(X,Z), travelBetween(Z,Y).