18 replies to this topic

[Yoruichi-san]

You and I are playing a little game (that is in no way whatsoever related to any game played on this site *cough*). There are 12 objects, 4 of which have the property M. The goal is to choose an object with the property M.

However, you and I are playing by different rules. For each round, first there is the N phase, in which you secretly choose an object (write down its number or something), then there is the D phase, during which I pick an object and it is revealed whether or not the object has property M.

If the object I pick has the property M, I win, if not we keep going. During any N phase, after you choose an object, you can call 'STOP' and the game will end. Then you reveal your choices, and if at least one has the property M, you win. If none have the property M, I win.

What is your play?

Bonus: Generalize to a case of n objects, k of which have the property M.

[Yodell]

Spoiler for

not related in any way to a game on this site ???

wd Y-san .. u did it ...

edit... added spoiler

Edited by Yodell, 22 June 2012 - 10:01 AM.

[CaptainEd]

I guess neither of us knows which objects have property M, and we rely on a third party to give us a determination at the end of each N phase or the STOP event?

[Yoruichi-san]

I guess neither of us knows which objects have property M, and we rely on a third party to give us a determination at the end of each N phase or the STOP event?

Yes, or they could be, like, upside down cards or mahjong tiles or something like that that we shuffled.

[Yoruichi-san]

Or beakers of acid/base we test with litmus paper...or glasses of pepsi/coke we taste test...but not beakers of acid/base that we taste test...

(sorry, couldn't resist ;P)

[phil1882]

let me see if i have the riddle correct with an example.
let's say i have 12 playing cards, 4 of which are spades. all cards are over turned, so no one knows which is which.
player 1 chooses 1 card, and keeps it down turned.
then player 2 chooses 1 card. player 2's card is revealed. if it's a spade, he wins, else keep playing.
player 1 picks another card (assuming player 2 didn't win.) player 1 can call stop. if either of the two cards are spade, player 1 wins.
else, player 2 wins.
sound good?

[CaptainEd]

I think the second player could choose one of the cards chosen by the first player, as the first player's choices are secret.

[bonanova]

Spoiler for my guess

The game seems simply to determine when to say Stop.
Seems that 2 draws puts your winning chances above 50%.
So I'm stopping after my 2nd draw.

[bonanova]

let me see if i have the riddle correct with an example.
let's say i have 12 playing cards, 4 of which are spades. all cards are over turned, so no one knows which is which.
player 1 chooses 1 card, and keeps it down turned.
then player 2 chooses 1 card. player 2's card is revealed. if it's a spade, he wins, else keep playing.
player 1 picks another card (assuming player 2 didn't win.) player 1 can call stop. if either of the two cards are spade, player 1 wins.
else, player 2 wins.
sound good?

Only possible difference is that player 2 [I think] doesn't know which card[s] player 1 has chosen.
E.g. P2 might choose one of them herself, and thus can 'steal' some of p1's chances.

[Yoruichi-san]

Yes, your choice is secret, and the object (beaker/tile/card) is not removed from the selection process.

And if I choose your card, your chances for stopping the second round aren't as good.