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for details.
We discontinued to sell IF/Prolog Dec 31. 2003.
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This site is maintained as a community service only.
The Smith family and their three children want
to pay a visit but they do not all have the time
to do so. Following are few hints who will go
and who will not:
o If Mr Smith comes, his wife will come too.
o At least one of their two sons Matt and John will come.
o Either Mrs Smith or Tim will come, but not both.
o Either Tim and John will come, or neither will come.
o If Matt comes, then John and his father will also come.
The following query will solve the problem:
[user] ?- Mr_Smith_comes => Mrs_Smith_comes,
| Matt_comes \/ John_comes <=> 1,
| Mrs_Smith_comes # Tim_comes <=> 1,
| Tim_comes <=> John_comes,
| Matt_comes => John_comes /\ Mr_Smith_comes,
| label(Mr_Smith_comes, Mrs_Smith_comes,
| Matt_comes, John_comes, Tim_comes]).
Mr_Smith_comes = 0
Mrs_Smith_comes = 0
Matt_comes = 0
John_comes = 1
Tim_comes = 1
yes
| 
