It's ready! Acuitas can play the text version of Allergic Cliffs and is often able to determine one of the secret rules by which the cliffs operate. Watch the video watch the video
In a previous blog I discussed how Acuitas chooses moves based on a simple heuristic that tries to replicate successes and avoid repeating failures. The part I haven't fully discussed yet is the final version of rule formation. Acuitas attempts to generalize from the results of past moves to derive rules of cause and effect that indicate when the cliffs sneeze. At this time all possible move results are reduced to the two goal-relevant outcomes (succeed or fail), and generalizations are made by looking at commonalities among all actions that share the same result. I started by just comparing pairs of actions, then upgraded the algorithm to look at the entire pool of past actions for feature combinations common across two or more of them.
For the moment, all rules are given in positive form. So, supposing the rules for the current game round divide the zoombinis onto the lefthand bridge if they have a blue nose or the righthand bridge if they do not, you'll never hear Acuitas say, "If a guide puts a zoombini who does not have a blue nose on a lefthand bridge, a guide fails," or "If a guide puts a zoombini does not have a blue nose on a righthand bridge, a guide succeeds." Instead you would get "If a guide puts a zoombini who has a blue nose on a righthand bridge, a guide fails," or any of "If a guide puts a zoombini who has a [red, orange, green, purple] nose on a lefthand bridge, a guide succeeds."
I ended up not having time (in my completely self-imposed schedule) to implement experiments (purposely choosing moves that will falsify or confirm tentative rules) or rule-following (informing moves by rules to increase chances of success). So Acuitas still plays the whole game using the "similar to previous move" heuristic. At the end of the game, he scores all tentative rules that have not yet been falsified and selects the one with the highest score to announce out loud. The scoring system is of interest.
Rules with more evidence behind them (more moves which had those combinations of features in common) score higher, naturally. But I found that I needed another trick to more successfully pick out which tentative rule was among THE rules of the current round. Any action which is the cause in one of THE rules tends to have a counterpart which differs by one feature and produces a different effect. So if you have a rule like "Put a zoombini with an orange nose on the lefthand bridge and you will succeed," then if THE rules are about orange noses, there ought to be opposing rules such as "Put a zoombini with an orange nose on the righthand bridge and you will fail," or "Put a zoombini with a blue nose on the lefthand bridge and you will fail." If these opposite counterparts don't exist, then the orange nose + lefthand bridge = success association is probably incidental; some other feature is driving the cliffs' behavior, and it just *happened* that all the zoombinis allowed to cross the lefthand bridge also had orange noses.
There's a lot more fun I could have with this and many directions to extend it, obviously, but for now I'm finished. I'm toying with the idea of possibly sharing the Allergic Cliffs text adventure (not any part of Acuitas, just the independent game script) for others to use. I would want to polish it first, add documentation, and possibly implement the higher difficulty levels, so I can't say when that might happen.
Until the next cycle,
Jenny
