This game is similar to "rock, paper, scissors" in that two players independently pick one of the six things, and if one thing somehow "beats" the other, then that player wins. If both players pick the same thing, they repeat until someone wins.

Life grows on Earth.
Water douses Fire.
Air resists Cold.
Life drinks Water.
Fire consumes Air.
Cold freezes Water.
Earth smothers Fire.
Life breathes Air.
Fire and Earth both warm Cold.
Air and Water both erode Earth.
Fire and Cold both destroy Life.
Water displaces Air.

A program that plays this game has a single set of probabilities for picking each of the six things. Assuming that the program's opponent knows what these probabilities are, what probabilities will give the program the best chances of winning?

What if the rules of the game are changed so that "Water displaces Air" is replaced with "Air ripples Water"?

(In reply to re(2): First part solution? / Second part solution by Matt)

Matt, I don't know where you're getting your numbers from, but if the opponent picks Fire, he will only win if the computer picks Air (10%), Cold (10%) or Life (20%), which only gives him a 40% chance of winning. It is the same for whatever he picks. The opponent only will win 40% of the time.

Posted by yocko on 2005-06-21 08:59:11