% Source: http://www.cs.bgu.ac.il/cgi-bin/genaim/TerminWeb/term_check?example=sublist

append([],Ys,Ys).
append([X|Xs],Ys,[X|Zs]) :- append(Xs,Ys,Zs).

sublist(X,Y) :- append(P,_,Y), append(_,X,P).