  prefers(pál,beer).
  prefers(éva,cola).
  prefers(józsi,wine).
  prefers(jenő,beer).
  prefers(imre,beer).
  prefers(jani,cola).
  prefers(pista,wine).
  
  served(sarok,wine).
  served(sarok,beer).
  served(hullám,beer).
  served(hullám,wine).
  served(hullám,cola).
  
  visits(Student,Pub):-prefers(Student,Drink),
                    served(Pub,Drink).
                   
 
 
