I place nine cards on a table, 1 through 9, face down. They are grouped in triplets. First you pick a triplet, and then I pick another triplet. Then we each reveal a random card from the triplet we picked, and the higher card wins.
I know what cards are in which triplets, but I don't know which random cards we will reveal within those triplets. How can I arrange the cards such that, no matter which triplet you pick, I am more likely to win than you?
(This game is taken from an article by Martin Gardner called "Nontransitive Paradoxes", which attributed it to Leo Moser and J. W. Moon.)