NPC modeling

Protagoras · 2007-01-22T17:26:35

I'm curious as to whether there are any existing resources (ideally C++, but I'm flexible) for doing something like the following, or if anybody has a much better way to do this sort of thing than I'm describing. I'd like an NPC to use stereotypes and previous information to interpret new data and choose a response. Suppose the NPC is a merchant, who is supposed to haggle over the price of some good he sells. Consider two cases, first one where the player's initial offer is high (high enough to make the merchant consider it a profitable transaction), the second where the initial offer is low. First, high offer. There are lots of reasons someone might make a high offer. He might just be in a hurry. He might be generous. He might be rich. He might mistakenly think the item is worth much more than it is. The item may be worth more than the merchant thought. The potential buyer may be attempting some sort of con which will be facilitated by ingratiating himself with the merchant. How likely the merchant thinks each possibility is will depend on other things the merchant may believe. If the potential buyer is expensively dressed, the rich theory seems more likely. If the merchant doesn't actually know much about items like this, the theory that it's worth more than he thought becomes more likely. If the potential buyer is a stranger, the con hypothesis looks more likely. If he's a revered local hero, the generous theory looks more likely. Any theory looks better if all the others look bad. Depending on which theory the merchant accepts, he may react in different ways, and his beliefs may change. If the merchant decides the potential buyer is being generous, he'll likely develop a more favorable opinion of the potential buyer, and likely make a counter-offer that isn't much higher (or just accept the offer, depending on local customs concerning how long you're supposed to haggle). If the merchant decides the potential buyer is trying to con him, he'll both develop a more hostile attitude toward the potential buyer (making the con theory more likely in future interactions) and make an inflated counter-offer. I hope it's obvious how the converse would proceed. A low offer from somebody he likes might be accepted (it may be an emergency, after all), but will lower his opinion of the person making the offer, making it harder for the person to get more favors in the future. A low offer from a stranger reinforces the belief that strangers in general are obnoxious tightwads, and certainly this one in particular is, and thus make it more likely that if the person makes a high offer in the future for some other item the merchant will guess con or decide the item must be more valuable than he thought. And so forth. Anybody do AIs that model anything like this?