tpProlog/tp4/train.pl

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   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).
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  11 train(X,Y):-directTrain(X,Y).
  12 train(X,Y):-directTrain(Y,X).
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  15 travelBetween(X,Y):- train(X,Y).
  16 travelBetween(X,Y):- train(X,Z), travelBetween(Z,Y).
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