formulas(favorable_models).
  ((s4 = 5) & (s5 = 6)) | ((s4 = 6) & (s5 = 5)) | ((s4 = 5) & (s6 = 6)) | 
  ((s4 = 6) & (s6 = 5)) | ((s5 = 5) & (s6 = 6)) | ((s5 = 6) & (s6 = 5)).
end_of_list.

