Similar problems arise in contract bridge, where players have a name for it--"restricted choice". I've actually always wondered if mathematicians have a name fo

Similar problems arise in contract bridge, where players have a name for it--"restricted choice". I've actually always wondered if mathematicians have a name for it. Anyone know? The most common example is this: say you and your partner have nine cards combined in a suit, and you're missing four cards: the queen, the jack, and two unimportant low cards. Bridge is played like hearts or spades, where one person leads a card and everyone else has to follow suit. It's your lead. You want to find the queen and the jack. If you guess right, you win the contract (= win a lot of points). If you guess wrong, you lose the contract. Your opponents want to hide the queen and the jack. Assume that your opponents, if one had both missing high cards, are devious enough to randomly play one or the other. You play the ace, and one defender drops the queen. What are the odds they have the jack? Hint: they're not 50/50.