# Sample Logic Problem
# p.5, Penny Press, Original Logic Problems, June 2002

                                # property value ...
wife    anne cathy eve fran ida
husband paul rob stan vern wally
day     1 2 3 4 5

%%                              # separator

# Anne was married on Monday, but not to Wally.

wife,day                a(anne, 1).             # 1x2-property constraint
wife,husband            b(anne, X) :- X \= wally.

# Stan's wedding was on Wednesday. Rob was married on Friday, but
# not to Ida.

husband,day             c(stan, 3).
husband,day             d(rob, 5).
husband,wife            e(rob, X) :- X \= ida.

# Vern (who married Fran) was married the day after Eve.

husband,wife            f(vern, fran).
                                                # 2x2-property constraint
husband,day wife,day    g(vern, X, eve, Y) :- X is Y + 1.