Will the day that the prisoner dies in my Unexpected Hanging Paradox markets be a surprise?
60
1.6K
1.2K
resolved Aug 22
Resolved
YES

I just made five markets for the Unexpected Hanging Paradox group that ask on what day the prisoner in the paradox will die. These will be resolved on August 21 - August 25, with one of them resolving to YES on the day the fictional prisoner dies, and the others resolving to NO.

/JosephNoonan/unexpected-hanging-paradox-will-the

/JosephNoonan/unexpected-hanging-paradox-will-the-b868b0ea1944

/JosephNoonan/unexpected-hanging-paradox-will-the-3ec27a5399f0

/JosephNoonan/unexpected-hanging-paradox-will-the-439dbd22774d

/JosephNoonan/unexpected-hanging-paradox-will-the-77d7ee47594c

This market resolves to YES if, on the day that the prisoner dies, the corresponding market is trading, on average, below 50% prior to resolution. I will be using midnight in the Central time zone as the cutoff between days.

At the request of a trader, I'm adding a sha256 hash of some text that reveals the answe (obviously, it's more than just stating the day, since then you could crack it in five guesses). No one will be able to tell what this is the hash of until resolution, but this will ensure that I can't change the day now that it's already decided.

3f75dc7c733335e5af1dcf7b90f384a16e6943e8e44bd95b7c4544185a7c04b3

Get Ṁ200 play money

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predicted YES

I've been wanting to make a sequel to this series of markets but didn't have another paradox that would fit well with the prediction market format. But I recently came across Cover's paradox, which works perfectly for a prediction market.

predicted YES

The input for the hash code was

Surprise! Were you expecting me? Hm, maybe not. Today is Tuesday, the day of your doom.

You can check it here: https://emn178.github.io/online-tools/sha256.html

predicted YES

Does anybody want me to calculate the exact average, or are we all fine with resolving it YES now?

bought Ṁ100 of NO

@JosephNoonan oh shit I missed the "on average" part

bought Ṁ1,500 of YES

Seems unnecessary to me

sold Ṁ104 of NO

@JosephNoonan anyway, I guess I'll bite that bullet. I've sold now just resolve

bought Ṁ15,000 of YES

Since there may be some confusion behind my trading on this market, let me share the reason for the YES.

Many traders suggested I should commit to it being a surprise, and this seems like the perfect way to do it. It is an experiment to learn the result of such training, and I allocated myself a large budget for it.

I just wanted to learn some market dynamics, guys.

bought Ṁ0 of NO

@JosephNoonan I feel like someone has filled my NO limit orders using insider knowledge...

predicted YES

@FlorisvanDoorn To be fair, you probably shouldn't have placed limit orders on a market where the top YES holder is known to have inside info. But I can pay you back for the cost of the limit orders if you want. The total amount was 200, right?

bought Ṁ1,000 of YES

@JosephNoonan I didn't realize you allowed yourself to continue trading once the week started. But that was just my mistake: I assumed it, but it was well within your right to do it.

And don't worry about paying back: I think I made more by quickly trading on the other markets once I realized what happened.

predicted YES

@FlorisvanDoorn Yeah, I see you made 840 on the Tuesday market

bought Ṁ10 of NO

@FlorisvanDoorn What did you realize happened? I'm trying to work out why the tuesday market spiked before resolving

predicted YES

@HastingsGreer The market creator bought 15k shares of YES on this market to ~98%. I reasoned that they would only do that if they knew that this market would resolve YES, and that could only be the case if the chosen day was Tuesday.

So my limit orders were helpful to generate a notification for this purchase, but 3 limit orders of 200 mana each was a bit expensive for that notification. :-)

predicted YES

@JosephNoonan OK, I don't see any objections, so I resolved it.

predicted YES

@HastingsGreer

I'm trying to work out why the tuesday market spiked before resolving

The prisoner heard the executioner's footsteps coming.

predicted YES

Maybe my 500 mana bet wasn't enough to convince people it will be a surprise. Do people think I should bet more?

predicted NO

@JosephNoonan I gotta say people's probabilities have been way off what i would have expected.

predicted YES

@JosephNoonan Yes! I trusted you that you wouldn‘t screw this up, but I‘m getting less and less convinced the longer it takes.

Edit: Thanks!

predicted YES

The markets currently give the prisoner a 108% chance of dying.

predicted YES

@JosephNoonan Poor guy :)

This might have worked better as a single multi-choice market

predicted YES

@rpominov There are some drawbacks to it, but actually I'm glad I did it as five separate markets. I kind of had to do it that way because I don't know how to get the probabilities of individual options in a multiple choice market from the API, but I do know how to get the probability from a binary market. So I have to have them as binary markets in order to resolve this one.

Regardless, I think there are other benefits of having it be five separate markets:

  • If the prisoner survives a day, then I can immediately resolve that market to NO at the end of the day, rather than having to wait until the prisoner dies.

  • For some reason, it just feels more exciting/suspenseful for there to be a market for each day.

  • Having five markets instead of one increases the chance that people will see them.

  • They start out with double the liquidity (of course, this also means it cost me double to make them, but they made back that cost long ago through UTBs, so I actually profited overall from that decision).

  • Binary markets still have better UI features, like the ability to sell shares and see everyone's position and profits.

  • At the beginning, most of the markets were hovering around 20% based on some traders assuming that the probabilities should be equal. Now, the consensus has changed to "Friday is less likely than the other days", but still, having every option start out at 20% as they do in a binary market might have discouraged people from trading early on (whereas, having them in their current state encourages trading for arbitrage if nothing else).

I don't think the total probability adding up to >100% is that big of a problem. It just means that someone can make some free mana by betting them down a little (in fact, it appears that someone has already done that, since the probabilities are back down).

predicted YES

@JosephNoonan Yeah, it's great as is too!

predicted YES

@JosephNoonan This is a useless warning considering that you already decided the day, but Tuesday really is likely to be the last day that has the probability under 50%.

predicted YES

@JosephNoonan Now the probabilities add up to 109%. Seemingly due to the lack of time decay on the Monday market.

predicted YES

@JosephNoonan I thought that once Monday resolves NO, the probabilities would be back in line, but people have already overcorrected and brought the remaining markets up to 110%.