Due: Wednesday, May 12, 1999
Questions to leora@watson.ibm.com

The problem is to formalize a slight modification of the first half of Wolves and Rabbits

Develop a theory justifying the following:

If you put a half dozen rabbits in a pen and care for them suitably for a period of a few months, you will generally end up with more than a half dozen rabbits in the pen. If however, you fail to feed them, then you will end up with no (live) rabbits in the pen. If they are all of one sex, and none of the rabbits is pregnant to start with, you will end up with no more than a half dozen rabbits no matter how long you wait. Indeed, in this case if you wait long enough, you will eventually have no live rabbits at all.

This problem is relatively open-ended. It's not possible to fully formalize this within a six-week period. You certainly don't want to get down to the level of detail of how much food a rabbit needs to survive. You want to ignore certain problems, such as the problem of one female rabbit and five male rabbits (or the converse), and whether the next generation will suffer more birth defects as as a result.

On the other hand, you will have to deal with certain issues. You definitely want to use a nonmonotonic logic. You will have to use a temporal representation that is more flexible than the standard situation calculus. You will have to talk about overlapping events, the duration of events, and events that "just happen." (Rabbits don't plan to multiply.) You will need to reason about conflicting defaults. (Rabbits typically stay alive from one moment to the next; but rabbits who are starved typically die. If there are n objects in a pen at one time, there will typically be n objects in the pen at the next time; but rabbits typically multiply.) some conflicting defaults are harder to represent than others.

Getting the temporal representation right is an important step, and worth a lot of credit in itself. Deciding how to simplify the problem so that you can get some results is another important part of the research project.

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