%% Connect strands of reasoning on an internet page together for the reader, as two notes converge

%% Finds all the strands of instructions which connect to a certain point, and connects them to it, and prints the graph in a depth first manner.

%% print(a,[[a,b],[c,d],[b,c]],Graph).

%% Graph = [[a, b], [b, c], [c, d]] ;

print(FirstItem,Items1,Graph) :-
	find_items(FirstItem,Items1,_Items2,[],Graph).
find_items(Item1,Items,Items,Graph,Graph) :-	
	not(member(Pair,Items)), Pair = [Item1,_Item2].
find_items(Item1,Items1,Items2,Graph1,Graph2) :-
	member(Pair,Items1), delete(Items1,Pair,Items3),
	Pair = [Item1,Item2], append(Graph1,[Pair],Graph3),
	find_items(Item2,Items3,Items2,Graph3,Graph2).

%% Finds duplicated content on the Internet

%% eliminate_duplicates([a,a,a,b,b,c],[],List).

%% List = [a, b, c] ;

eliminate_duplicates([],List,List).
eliminate_duplicates([Item|Items1],List1,List2) :-
	delete1(Items1,Item,[],Items2), append(List1,[Item],List3),
	eliminate_duplicates(Items2,List3,List2).
delete1([],_,Items,Items).
delete1([Item|Items1],Item,Items2,Items3) :- 
	delete1(Items1,Item,Items2,Items3), !.
delete1([Item2|Items1],Item1,Items2,Items3) :- 
	append(Items2,[Item2],Items4),
	delete1(Items1,Item1,Items4,Items3).