/* Describing when two elements in a list are consecutive */
consec(U,V, U.V.X).
consec(U,V, W.X) :- consec(U,V,X).


nothead(V,[]).
nothead(V,W.X) :- V \== W.
notconsec(U,V,[]).
notconsec(U,V,[W]).
notconsec(U,V,W.X) :- U \== W, notconsec(U,V,X).
notconsec(U,V,U.X) :- nothead(V, X).