Indeed, it's quite complicated :) While the fly can react faster, we can react, slower, ...but potentially many moves ahead of it. I do not think of where the fly is going to go in one move, rather something more like the center point of where it could go in many moves. Their ability to move swiftly is higher, our ability to calculate complexity is higher. Amusingly, we are often evenly matched. Best not to seek each others demise if possible. --Mr. Miyagi