75392e54c7
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@757 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
64 lines
1.5 KiB
Plaintext
64 lines
1.5 KiB
Plaintext
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:- object(farmer,
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instantiates(state_space)).
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:- info([
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version is 1.0,
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author is 'Paulo Moura',
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date is 1998/3/23,
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comment is 'Farmer, cabbage, goat, and wolf state space search problem.']).
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initial_state(start, (north, north, north, north)).
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goal_state(end, (south, south, south, south)).
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next_state((Cabbage, Goat, Wolf, Farmer), (FCabbage, Goat, Wolf, FFarmer)) :-
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same_side(Farmer, Cabbage),
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\+ same_side(Goat, Wolf),
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flip(Farmer, FFarmer),
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flip(Cabbage, FCabbage).
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next_state((Cabbage, Goat, Wolf, Farmer), (Cabbage, FGloat, Wolf, FFarmer)) :-
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same_side(Farmer, Goat),
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flip(Farmer, FFarmer),
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flip(Goat, FGloat).
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next_state((Cabbage, Goat, Wolf, Farmer), (Cabbage, Goat, FWolf, FFarmer)) :-
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same_side(Farmer, Wolf),
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\+ same_side(Cabbage, Goat),
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flip(Farmer, FFarmer),
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flip(Wolf, FWolf).
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next_state((Cabbage, Goat, Wolf, Farmer), (Cabbage, Goat, Wolf, FFarmer)) :-
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\+ same_side(Cabbage, Goat),
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\+ same_side(Goat, Wolf),
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flip(Farmer, FFarmer).
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flip(north, south).
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flip(south, north).
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same_side(north, north).
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same_side(south, south).
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print_state((Cabbage, Goat, Wolf, Farmer)) :-
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(Cabbage = north -> write(c); write('_')),
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(Goat = north -> write(g); write('_')),
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(Wolf = north -> write(w); write('_')),
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(Farmer = north -> write('f.<__>.........._'); write('_..........<__>.f')),
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(Cabbage = north -> write('_'); write(c)),
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(Goat = north -> write('_'); write(g)),
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(Wolf = north -> write('_'); write(w)),
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nl.
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:- end_object.
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