?- consult('combinatorial_sets.pro').
true.

?- perm(s(cat,dog),p(A,B)).
A = cat,
B = dog .

?- perm(s(cat,dog),p(A,B)),write(p(A,B)),nl,fail.
p(cat,dog)
p(dog,cat)
false.

?- perm(s(red,yellow,blue),p(X,Y,Z)),write(p(X,Y,Z)),nl,fail.
p(red,yellow,blue)
p(red,blue,yellow)
p(yellow,red,blue)
p(yellow,blue,red)
p(blue,red,yellow)
p(blue,yellow,red)
false.

?- comb(set(2,3,5),comb(A,B),extras(C)).
A = 2,
B = 3,
C = 5 .

?- comb(set(2,3,5),comb(A,B),extras(C)),write(result(combo(A,B),extras(C))),nl,fail.
result(combo(2,3),extras(5))
result(combo(2,5),extras(3))
result(combo(3,5),extras(2))
false.

?- comb(set(2,3,5,7),comb(A,B),extras(C,D)),write(result(combo(A,B),extras(C,D))),nl,fail.
result(combo(2,3),extras(5,7))
result(combo(2,5),extras(3,7))
result(combo(2,7),extras(3,5))
result(combo(3,5),extras(2,7))
result(combo(3,7),extras(2,5))
result(combo(5,7),extras(2,3))
false.

?- comb(set(2,3,5,7,9),comb(A,B),extras(C,D,E)),write(result(combo(A,B),extras(C,D,E))),nl,fail.
result(combo(2,3),extras(5,7,9))
result(combo(2,5),extras(3,7,9))
result(combo(2,7),extras(3,5,9))
result(combo(2,9),extras(3,5,7))
result(combo(3,5),extras(2,7,9))
result(combo(3,7),extras(2,5,9))
result(combo(3,9),extras(2,5,7))
result(combo(5,7),extras(2,3,9))
result(combo(5,9),extras(2,3,7))
result(combo(7,9),extras(2,3,5))
false.

?- comb(set(cat,dog,bird,bees,chicken),comb(A,B),extras(C,D,E)),write(result(combo(A,B),extras(C,D,E))),nl,fail.
result(combo(cat,dog),extras(bird,bees,chicken))
result(combo(cat,bird),extras(dog,bees,chicken))
result(combo(cat,bees),extras(dog,bird,chicken))
result(combo(cat,chicken),extras(dog,bird,bees))
result(combo(dog,bird),extras(cat,bees,chicken))
result(combo(dog,bees),extras(cat,bird,chicken))
result(combo(dog,chicken),extras(cat,bird,bees))
result(combo(bird,bees),extras(cat,dog,chicken))
result(combo(bird,chicken),extras(cat,dog,bees))
result(combo(bees,chicken),extras(cat,dog,bird))
false.

?- halt.