permutation(L,P).
permutation([],[]).
permutation([a],[a]).
permutation([b,c],[b,c]).
permutation([b,c],[c,b]).
permutation([d,e,f],[d,e,f]).
permutation([d,e,f],[d,f,e]).
permutation([d,e,f],[e,d,f]).
permutation([d,e,f],[e,f,d]).
permutation([d,e,f],[f,d,e]).
permutation([d,e,f],[f,e,d]).

permutation([X],[X]).
permutation([Y,Z],[Y,Z]).
permutation([Y,Z],[Z,Y]).

