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Comment by rjmill | Hacker News Reader

> They were at a casino in Monte Carlo when Dán met her future husband, John von Neumann, for the first time. He explained that he had perfected a way to ensure that you could win roulette every time, and promptly lost all his money trying to prove his point.

Magnificent. I can't explain why I'm so delighted by this, but the mental image makes me happy.

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You left out the next sentence, which was hilarious too: "Afterwards, he asked Dán to buy him a drink."

She must have been instantly smitten, what a charmer.

This is the most hilarious "meet cute" I've ever read.

This implies that JvN was a gambler , but not a computer*

(*) Okay, not a 1980s-level computer

https://en.wikipedia.org/wiki/The_Eudaemonic_Pie

)

This was an earlier husband of hers, not von Neumann.

Yes, the first husband was an inveterate gambler, but she did meet JvN in a casino too, with an absurd story.

We know him for his researches in games of chance (& skill), but here he definitely took his chances :)

"Chess is not a game. Chess is computation." --JvN

Oops, I wasn't reading carefully and got this wrong -- this was in fact von Neumann.

I wonder if it was the basic gambler’s fallacy- which to be honest I still can’t grasp. I fully understand that conceptually every roll is completely independent and red/black is always ~50/50, but it’s very rare to see 20 straight black rolls in a row. Can someone try and explain it (if there even is anything to explain)?

Easier to explain with coin flips. Let’s say we do 100 flips - we know the “most likely” thing to happen is 50 heads and 50 tails. The actual probability of that is C(100, 50) / 2^100 = 0.079.

So about an 8% chance. You’re significantly more likely (ie 92% chance) to see _something else_. And that’s _the most_ likely outcome.

So tldr - it’s not so much that “you never see an all tails sequence in practice” - you’re actually unlikely to see any particular sequence. All the probabilities get astonishingly low very quickly.

Another point is that roulette is never 50/50 for red/black (there are 0, and sometimes 00 which are uncolored)

It is a fun story but it does not have to be true.

I think von Neumann would understand some basic probability already by then.

Or maybe not? But at least there is a non-zero probability that it did not happen like that.

Sure, he would have known probability, but apparently he knew how to make up a good story to charm someone.

Sounds like his losses were a good investment.

By that time he'd already created the foundations for game theory with his minimax theorem of zero-sum games. I think its more likely that he knew was he was doing and expected to lose the money.

Old roulette wheels had large flaws, even in the 1960s: https://thehustle.co/professor-who-beat-roulette. 30 years earlier they must have been worse. So there is a chance he noticed some anomaly that he tried to exploit.

That article was a good read. That is a possibility.

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