% CPSC 312
% Author: Steven Wolfman
% Based on work by David Poole

% month_num(MonthName, MonthNumber) is true if MonthNumber is the 1-based equivalent
% to the three-letter constant MonthName for a month (in English on the solar calendar).
month_num(jan, 1).
month_num(feb, 2).
month_num(mar, 3).
month_num(apr, 4).
month_num(may, 5).
month_num(jun, 6).
month_num(jul, 7).
month_num(aug, 8).
month_num(sep, 9).
month_num(oct, 10).
month_num(nov, 11).
month_num(dec, 12).

% A date is of the form ce(Y, M, D) where:
% + Y is the year as a number; 1971 in our example above
% + M is the month as a three-letter constant; dec in our example above
% + D is the day of the month as a number; 25 in our example above.

% before(D1, D2) is true when date D1 is before date D2
before(TODO, TODO).