I have a program I've written in prolog that deals with the classic rat in a maze example, but I'm trying to add to it a bit of functionality. Basically, I want to keep a count of how many rooms have been traversed so far, and ensure that a certain condition has been met at least once in the past three traversals (rooms in the maze).

The code I have so far is as follows:

connected(X,Y):- d(X,Y);d(Y,X).

path(A,B,Path):- go(A,B,[A],Q), reverse(Q,Path).

go(A,B,P,[B|P]):- connected(A,B).

go(A,B,Visited,Path):- connected(A,C), C\==B, not(member(C,Visited)), go(C,B,[C|Visited],Path).

cheese(X):- cheese(X).

I realize I probably don't need the last predicate since I could just directly say cheese(c), cheese(b), etc, but it's mostly there to remind myself of where I'm going with this and to actually write the check for cheese into the traversal. The main issue I'm having here is that I'm unsure how to have the counter increment/decrement appropriately on traversal or backtracking. Any help would be appreciated. Thanks.