The next problem may be way too easy, but will post it anyway.
Riddick, trying to escape from the space police, lands on a deserted planet. How many cops should the space police send to the planet, so that Riddick will be eventually caught?
We assume that the planet is a perfect sphere and the speed of Riddick and all cops is the same. All of the characters have perfect information about the location of the others and make instant decisions in real-time. Also, they are dots.
P.S. The question seems very natural, I hope it is not a repeat.