Longest Path

longest path.

% longest path (without loops)
:- import bagMax/2 from aggregs.
:- import member/2 from basics.

longpath(X,Y,P)(D) :- edge(X,Y,D), P=[F|R], \+member(F,R).
longpath(X,Y,P)(D) :- 
	bagMax(longpath(X,Z,[Z|P]),D), edge(Z,Y,D), Y\==Z, \+member(Y,P).

:- hilog maximum.  maximum(X,Y,Z) :- X @< Y -> Z=Y ; Z=X.

edge(a,b,5).
edge(a,b,6).
edge(a,d,4).
edge(d,b,5).
edge(b,c,3).
edge(b,c,4).