The statement :
Four couples in all
Attended a costume ball.
2
The lady dressed as a cat
Arrived with her husband Matt.
3
Two couples were already there,
One man dressed like a bear.
4
First to arrive wasn't Vince,
But he got there before the Prince.
5
The witch (not Sue) is married to Chuck,
Who was dressed as Donald Duck.
6
Mary came in after Lou,
Both were there before Sue.
7
The Gipsy arrived before Ann,
Neither is wed to Batman.
8
If Snow White arrived after Tess,
Then how was each couple dressed?
My code is here , but it returns false :
sol(S):-
S=[[1,L1,M1,LD1,MD1],
[2,L2,M2,LD2,MD2],
[3,L3,M3,LD3,MD3],
[4,L4,M4,LD4,MD4]],
member([_,_,matt,cat,_],S),
member([ALR,_,_,_,bear],S),
(ALR =:= 1 ; ALR =:= 2),
not(member([1,_,vince,_,_],S)),
member([VN,_,vince,_,_],S),
member([PS,_,_,_,prince],S),
VN < PS ,
member([_,_,chuck,witch,donald],S),
not(member([_,sue,_,witch,_],S)),
member([MRY,mary,_,_,_],S),
member([LOU,_,lou,_,_],S),
member([SUE,sue,_,_,_],S),
MRY > LOU,
MRY < SUE,
member([GPS,_,_,gipsy,_],S),
member([ANN,ann,_,_,_],S),
GPS < ANN ,
not(member([_,_,_,gipsy,batman],S)),
not(member([_,ann,_,_,batman],S)),
member([SW,_,_,snowwhite,_],S),
member([TS,tess,_,_,_],S),
SW > TS ,
perm([sue,mary,ann,tess],[L1,L2,L3,L4]),
perm([matt,lou,vince,chuck],[M1,M2,M3,M4]),
perm([cat,witch,gipsy,snowwhite],[LD1,LD2,LD3,LD4]),
perm([donald,prince,batman,bear],[MD1,MD2,MD3,MD4]).
takeout(X,[X|R],R).
takeout(X,[F|R],[F|S]) :- takeout(X,R,S).
perm([],[]).
perm([X|Y],Z) :- perm(Y,W), takeout(X,Z,W).
Any solution ?