assign(domain_size,13).         %ambigous date has day less than 13
assign(max_models,-1).
set(arithmetic).

formulas(ambigous_dates).
  day   != 0.                   %day in [1..12]
  month != 0.                   %month in [1..12]
  day != month.                 %if day = month there is no ambiguity
  month = 12. 
end_of_list.

