%% traverse(+Antecedent,+Consequent,+List)
%% Checks an argument is valid, or proven by parts given
%% An argument is given by If <Antecedent>, then <Consequent>
%% List is a list of reasons for the argument

%% ?- traverse(a,c,[[a,b],[b,c]],_).
%% ?- traverse(a,d,[[a,c],[c,d],[a,b],[b,c]],_).

traverse(A,C,List) :-
	traverse1(A,C,List,_).

%% traverse(+Antecedent,+Consequent,+List,-List)
%% Most of the variables are the same as for traverse/3
%% List2 is List with all the found reasons removed

traverse1(_,_,[],[]).
traverse1(A,C,List,List4) :- 
	delete(List,[A,B],List1), delete(List1,[B,C],List2),
	traverse1(A,B,List2,List3), traverse1(B,C,List3,List4).