Show HN: Stellar Jackpot | Hacker News Reader

Show HN: Stellar Jackpot

stellarjackpot.com

56 pointsthijser30 comments

Neat. You're trusting a website that doesn't list who runs it (whois says it's a guy named Mathijs Vogelzang out of Paris) or what their intentions are to provide a fair lottery to anonymous addresses. Given enough lotteries you could backtrace the results and make sure the distributions are probabilistically random, but what's stopping the owner from entering a sufficiently large pool and 'randomly' selecting an address he controls as the winner?

Oh, and for providing this service you automatically lose 2% off the top.

There are far better ways to waste your virtual disney dollars.

I'm pretty sure the poster (thijser) is Mathijs Vogelzang based on his username. His HN profile is a few years old and he says where he works on his profile. I'm not saying whether people should trust this or not, but I think you may be being a bit unfair.

I don't this he is being the slightest bit unfair. At least in the US, lotteries make a lot of money for the people running them, but that is normally shared with local communities or governments. If you participate in lotteries, you pretty much are guaranteed to be throwing your money away, but at least losing people do get some benefits from the system, as the proceeds get spent in their area.

In this case, one guy just collects the money. No matter what his intentions or honesty, he collects.

If people want to throw him their "cash", fine... but they should absolutely realize what they are doing.

I'm the creator, thanks for the insights. This was really just a fun project to explore the Stellar API (which is really good, and I hope they will reach their goal and transform international payments).

It seems the attention on hacker news drew quite some payments into the system, whereas I had thought that it would just stay in the play money range forever. The lottery aspect I hadn't thought about. I'm eager to transform the model to make it less lottery like as I certainly don't want to violate any laws, but am a bit unsure about exactly how. There could be a small chance that 100% of the money goes to a charity, or that there is somehow a matter of skill involved in the exact amount you send. (FYI, the only other piece of information that can be sent along with a Stellar payment is one 32-bit integer ID). Any suggestions are welcome.

Don't listen to people trying to pressure you on how you spend you money. People love to shame others.

You made a lottery. Nobody has to play. Do whatever you want with the money. Don't give it to charity because someone else told you to.

I agree with this post, you created it and people are using it so do what you want with it. It is a great idea, So well done!

I think giving the margin to a charity would be a great idea. I was thinking of implementing a stellar charity lottery, but you have been faster it seems :) As an added benefit people might be more likely to play if they know they are doing so for a good cause. Everybody wins! :) I think there are a few charities on stellar already

"…redistribution game…" – what a lovely euphemism!

And finally, a website to directly address the problem that anonymous lottery operators have too little wealth, and credulous altcoin lottery players have too much.

I can't decide if this is fun, but fiscally pointless, or kinda brilliant.

It looks like a pretty simple app, which I doubt took too much time to put together, and is likely incredibly cheap to run. Assuming the most recent two hours are more representative of engagement than the previous two (not a given by any means, and no I haven't been tracking this before then), it looks like it's producing several hundred Stellars an hour minimum for the creators.

Stellars aren't worth much right now, and may never be (I'll leave that sort of speculation to those with more knowledge of the subject), but this seems like a cheap and quick way to build a stockpile.

Anyway, food for thought.

I just won the last jackpot of 37682.96 stellar. Not sure what I can do with it hehe.

play again :P

or give it to a charity, I think there are a few that have a stellar account, for example miri

I wonder if you could game that jackpot. Statistically, with even-odd tickets the net value of the ticket is always less than the ticket cost -- meaning statistically you loose money (ex: a $2 ticket, on average, has a return of $1.50). If you could monitor the jackpot and, at the very last minute, more than double the current pot then you'd have over a 50% chance of winning. You'd win some and loose some, but statistically over time I think you'd end up positive.

Any mathematicians want to chime in?

EDIT: As fela, zck, and thedufer pointed out below, this would not work in fact. Thank you guys for the math lesson!

If you exactly double the pot right before a drawing, you'll have a 50% of losing 50% of the pot (what you put in) and a 50% chance of winning 48% of the pot, with an expected value of, you guessed it, losing 2% of your money each time.

It's not a coincidence that this 2% is equal to the cut taken. That will always be your expected loss. Unless it does not behave as advertised, you can't game it.

I said "more than double the pot". So your odds would be over 50%. And you win the entire pot if you win, unless I'm misunderstanding? You don't have a 50% chance of winning 48%, you have a >50% chance of winning 98%.

The site says "The draw is weighted by payment amount". I'm assuming that's linear -- if I put in 1 stellar, and you put in 2, you're twice as likely to win than you are. If the weighting is different (say, you're four times as likely to win), then that changes the math.

Let's say that before you put anything in, the pot holds X stellar. You then put in Y stellar. So I'm assuming that you win with Y/(X+Y) probability. If you win, you win .98(X+Y). If you lose, you lose everything.

So your expected value is the chance you win (Y/(X+Y)) times the return (.98(X+Y)).

     Y      
    ---  * .98 * (X+Y)
    X+Y

The (X+Y) parts cancel, and you end up with .98Y, or less than what you put in. And since we didn't use the fact that Y>X, it's independent from the actual values of X and Y, so it holds no matter what they are^1.

[1] Assuming they're positive, and X+Y is nonzero.

I used 50% because it is easy to work with, and it shows that 50% isn't a magical breakeven point - which would have to exist if you agree that the expected return is a continuous function and you believe there is a point where your expected return is greater than 0.

> You don't have a 50% chance of winning 48%, you have a >50% chance of winning 98%.

You only win 48% in my model because the other 50% is your own money that you're getting back.

Anyway, let's do it generically. You have put in x of the money (more than 0.5 in your scenario, but it doesn't matter). Then there are two ways to formulate your expected return.

First, what I was doing before - if you lose, you lose x and if you win you win (.98-x). You have x chance of winning, so expected return is:

(1-x) chance of losing x + x chance of winning (.98-x)

(1-x) * -x + (.98-x) * x

(x-1 + .98-x) * x

-.02x

Alternatively, you initially give up x and then have x chance of winning the whole pot, .98:

give up x + x chance of winning .98

-x + .98x

-.02x

So either way, no matter what portion of the pot is yours, your expected return is to lose 2% of the money you put in.

Well no matter how you look at it, the expected value is .98 of whatever you paid. So in the long run you're certainly going to lose 2% of what you invested.

But you wouldn't be getting just your money back, you'd be winning the entire pot. Unless I misunderstand how this works.

say the pot contains 20, and you pay 80, you will have 80% chance of winning 18 in addition to your 80 and 20% chance of losing everything, if you do this many times you will still on average lose

Right, so (.80 * .98(100) + .20 * 0) = 78.4. Which is 2% less than the 80 you paid to entry...

This makes more sense when I use an absolute (100), I think my mistake was in trying to calculate 100 as a variable amount, I must've made an error there. Thanks for explaining :)

Is there any way I can get str's by buying them somehow? It seems like I'm a bit too late with registrating my Stellar account

https://justcoin.com/ would be an option (appears to currently have the largest Stellar volume out of the few exchanges that trade it). Here are the current prices: http://coinmarketcap.com/currencies/stellar/

Just for fun, what would be the optimal strategy to play this game?

If you have x amount to spare, you could either put all x in one round, or spend x/N in N rounds.

I guess, the probability of winning might be optimal for some N > 1, but I am not able to come up with a formula for it.

Further optimisation of the N>1 strategy could be to stop entering into a round after winning and making a profit.

The expected amount is always 98% percent of what you put in, so the optimal strategy is to not play at all :)

It depends what you are optimizing for. In most cases playing multiple times will make you win very slightly less in the median case, countered by the fact that you can win multiple jackpots (obviously not too likely an event)

And stopping strategies usually mean having a big probability of winning little but have a small chance of losing a lot. Basically a reverse lottery, but you still lose on average.

Take 2%. That is almost a standard credit card fee. We are trying to get away from those level of fees with new types of currency.

Apparently I won. :) So I know it pays back.

Awesome idea., I just sent some Stellar to it.

I take it you have a lottery license?

I take it he lives in a country where one is required?

I don't know of any modern country where it's not required.

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