How Claude Shannon used information theory to cheat at Vegas roulette


Originally published at:


Not sure I would call this “cheating” - they used freely available information to (drastically) improve their odds. I’m sure that by now casinos have gotten laws enacted that prohibit this sort of activity, but what they did was not illegal.


I’ve always thought that once an extra device comes into play, it’s considered cheating.


I’m pretty sure whatever each casino says is cheating, is cheating. It’s a totally arbitrary rule. They throw “cheaters” out who count cards in their heads.


Tell that to the guys with the baseball bats.


It would have been illegal because they were using electronics to communicate to themselves. I would think that’s the rub.

If they were timing it in their heads like the scene in Hudson Hawk I would think that’s not prosecutable.


I’m pretty excited by this book, not much out there about Shannon. Thorp has written a little about their projects, but it seems he is reluctant to provide much detail. An interesting book about the roulette hack is “The Eudaemonic Pie”, about a group of physicists lead by Doyne Farmer, who expanded on Shannon’s and Thorp’s work in the 1970’s.


Fortune’s formula covers this also along with some other interesting stories about Shannon and the “Kelly formula” it’s a great read.


Casinos can walk out anyone who they believe is winning too often; no proof of cheating is required.


+1 for the Hudson Hawk reference!


This is not “cheating”, and even the article you link to on Nautilus has corrected themselves. (It now reads “the Las Vegas shark” instead of “the Las Vegas cheat”, and the word “cheat” now appears nowhere in the article.) Please correct your article as well.

In response to the rising popularity of blackjack computers in the late 70’s and early 80’s, Nevada passed NRS 465.075 in 1985, prohibiting “use or possession of device, software or hardware to obtain advantage at playing” casino games. Many other jurisdictions enacted identical laws in subsequent years. It is still not cheating, but now it is illegal. When Shannon and Thorp were working on roulette, these laws were still 20+ years in the future, and their activities were completely legal.

Some of the comments seem confused about the difference between what is cheating, what is illegal, and what a casino can kick you out for.

  • Cheating is a specific term defined in law (NRS 465.015, in Nevada) regarding altering the results or payout of a game.
  • Any number of actions related to gambling can be illegal without being cheating. Being an unlicensed bookie, using a roulette computer, putting down a $20 sports bet for your buddy while he drinks at the bar…
  • A casino can kick you out for any reason at all. I’ve never been given a reason, actually. Just “we don’t want your business.”

The main risk Thorp and Shannon took wasn’t being arrested, it was being beaten up. Vegas casinos were pretty openly run by the mob in the 60’s and 70’s. They didn’t care too much about the legality of what players were doing, just that they were bad for the bottom line; and they didn’t care too much about the legality of their countermeasures, just that they were good for the bottom line.

(The corporate takeovers of the 80’s, and various lawsuits against casino thugs starting in the 90’s, helped change those calculations, so things are now a lot safer.)


Really? I find myself convinced that whatever a casino says is cheating most definitely isn’t cheating!


To prove his point, I myself am only one degree of separation from Claude Shannon (worked with a faculty member in college who worked closely with him at Bell Labs.)


When asked: Who invented the computer ? the response is Turing and von Neumann.
And who invented Information Theory ? Shannon.
We tend to forget his 1937 Master’s Thesis “A Symbolic Analysis of Relay and Switching Circuits”. In this paper he shows that electrical switches can be used to perform logic functions, calculation , etc…
So he is the co-inventor of modern computers.


That sounds about right. A buddy and I were kicked out of a casino for 21 card counting back in the 80’s. Thorpe was our guiding star, along with Ken Uston. We were only mildly concerned about being beaten up. The pit boss called over two guys who barely fit into their three piece suits to escort us out.

We hadn’t won all that much money but the obvious “tell” of a card counter going for maximum edge is how we vary our bets frequently. I think what pushed them over the edge was a relatively lucky string of calling too many insurance bets correctly.

We’d have loved to have used a “George,” one of the names for assistant electronics, but we had a much simpler system that still worked. I would play while my buddy stood, counted cards (3 level +/- with a side count of aces and fives), and signaled me with finger pressure on my back. Our signaling was undetectable. A friend standing nearby holding the back of your chair is common and his fingers themselves were hidden by my back and the chair. Our technique let me drink quite a bit and banter with the dealer and/or pit boss, allying much of their suspicion.


Depending on how much you’re betting and winning dealers will tolerate card counting. I have a friend who is really good at it and would double up with a buddy of his that was equally as good. They were playing blackjack at a casino once and another patron kept playing a certain way that was messing up their own plays, after the patron left the dealer told them something like: “Man that guy really fucked up your guy’s hands” in a friendly way that revealed he knew they were counting. They played some more and made back some money before they left.


Their ideal customer is someone who doesn’t even enter the casino. They want people to walk up to the casino’s mail slot and empty the cash contents of their wallet into it.


Claude Shannon is a personal hero of mine. Understanding some of his work in information theory was enlightening for me. When you get it, it is amazing… Trying to explain to another person that information is likely more fundamental the universe than time-space, mass, or energy is like telling Trump he is a cretin - Bloody frustrating at best…


Ooh! Details please! :stuck_out_tongue:


Do you think his device would work on Chat Roulette, as well?