Friday, March 14, 2008

PI day Captcha

From Quantum Random Bit Generator Service via mathlog and wiskundemeisjes.

Captcha: "Completely Automated Public Turing test to tell Computers and Humans Apart".

PI Day, recycled.


  1. Would a politically correct human give the mathematically correct or incorrect answer? Head Start asserts there is quality in quantity. Physical reality demurs - but doesn't disgorge $billions of unregulated funding/year.

  2. Maybe we should replace the 'word verification'? I guess though it will be only a matter of time until these things can be cracked by robots (if not already the case). It can't be all that hard to extract the typically used equations for such purposes (that usually aren't scrambled like the otherwised used captchas).


  3. No Uncle Al, Headstart asserts that if you educate a large enough quantity some quality will raise to the top; otherwise you only get the George Bushes and Elliot Spitzers raising to the top. We already have enough them getting ahead on daddy's and grandmommy's money.

    I'm always willing to spend money on education and public libraries.

  4. Hee. It's true it's easy for a robot to crack but it's also the sort of thing that raises the barrier quite a bit as long as it's a minority practice. Especially when the equation is an image as here.

    Plus, it's fun practice for those of us who don't do such computations of a living. :)

    Do you think using residue-theorem integrals would positively affect the quality of your comments?

  5. Hi Bee,

    I’ve been trying to get through all day to make a comment, however the normal Captcha thing instead of showing distorted letters asked that I solve an equation involving trig functions and I didn’t have a damn calculator :-) Seriously, despite the recognition issue wouldn’t a computer easily be able to tackle such a test? I would think a better test would be to devise something that presents a query that would relate to the halting problem such as an extension of the Goldbach's Conjecture:

    Find a even number greater than 2 that is not the sum of up to n prime numbers.

    Of course if your Q Bit flippers at PI have the success that they believe possible, even this might not be able to do the trick ;-)



  6. Dear all,

    well, I don't think that they want to actively discriminate against people without knowledge of calculus - after all, the web site, Quantum Random Bit Generator Service, offers true random numbers generated from quantum physical process of photonic emission in semiconductors and subsequent detection by photoelectric effect for use in Monte Carlo simulations and similar scientific applications.

    So, to the potential users of the service, the Captcha problem should be solvable. And geeks finding delight in long sequences of random numbers probably also can do their chain rules ;-)

    Bee, Rilian - I agree: I'm also quite sure that the Captcha could be solved automatically - once one has understood the symbols (This should be possible by OCR? They have not been transformed, after all, so automatic pattern recognition might work?), the rest is a completely mechanical application of the rules of calculus.

    Anyway - I had a hearty laugh when I saw it, it's a great nerdy kind of joke ;-)

    - Stefan

  7. Hi Bee,

    With this use of the Captcha to distinguish bots from humans it truly comes down to what one is trying to prevent. If it is simply trying to prevent spamming the current system works pretty well as a determinant. Spamming depends on being able to get a lot out quickly to many with limited resource. Bill Gates several years ago suggested that when it came to email that each reception of a post should involve a mathematical query to the sending computer that would take it upwards of a few seconds to solve. It was reasoned that this delay for normal users even if it involved several recipients would not tend to be much of a bother. However, it would totally destroy the economy and thereby the feasibility for spammers. This proposal never went any further then this as I suspect since corporations would have been also affected by it in terms of their own use of spam. So this serves to prove that if you are rich and powerful its not spam, its acceptable business practice:-)



  8. Yeah. It's an excellent example for a co-evolution that is a complete waste of resources.

  9. Hi Bee,

    “Yeah. It's an excellent example for a co-evolution that is a complete waste of resources.”

    : Not actually on topic yet related

    I’m not surprised that you would view it this way in as you are a physicist. It seems that many equate the problem with only discovering how to find more rather then consider efficiency as being required. In looking around for what to amuse myself with last evening I had a look at the TED site to see what there was to find and stumbled across a recent talk given by the noted Biologist and genetics pioneer Craig Venter.

    His talk focused on our technical capability along with direction he suggested we take in the exploitation of it. He first let it be understood that we have moved beyond just simply being able to read the code of existing life forms to now the beginnings of the ability to design this code from the ground up. He saw the greatest initial value in all this is that it could and should be used in developing life forms that would use CO2 more efficiently then plants to create carbon base fuels.

    I came away wondering why he missed the point entirely that such fuels no matter how efficiently produced are still a far cry from what nature manages everyday with the consequence of fusion and doesn’t have carbon as a requirement although it too can be a consequence if fusion extends beyond basic hydrogen. Anyway, I found it ironic that biology would piggyback on the energy woes in an effort to increase funding, while still not recognizing that our current problems have not only to do with not having enough, yet rather the nature and economy of the source.



  10. Phil, another problem with the pay-in-CPU-time email filters are is that Moore's law makes it difficult to set the barrier height. Because cpu performance is increasing exponentially, what's appropriate for a new computer is prohibitive for one three years old. And what's appropriate for the median computer speed will be trivial for a high end machine bought in a year or two.

    And, like most modifications to the protocol, it either destroys the essential any-to-any nature of email, or it's only really useful if most people adopt it, and it's difficult to fluctuate into that kind of phase transition.

  11. This comment has been removed by the author.

  12. Hi Rillian,

    “another problem with the pay-in-CPU-time email filters are is that Moore's law makes it difficult to set the barrier height.”

    I’m aware of this difficulty and yet this applies to everything as it relates to computers; whether it be this, new software, web page content or media. Could this not all be mediated by the servers that form the gateway to the system? The problem of course is when something is shown to have little cost it is the often assumed to have similar value (can you imagine if we thought the same of air). I’d then rather have my email consume a bit more of my time and received a tad later then waste more time and expense by buying software and marking spam and yet still discovering that some reactive rather then proactive safeguard has marked a letter from a long lost friend as spam.

    “And, like most modifications to the protocol, it either destroys the essential any-to-any nature of email, or it's only really useful if most people adopt it, and it's difficult to fluctuate into that kind of phase transition.”

    I see these problems only as difficulties, not as reasons. The whole structure is built on protocol, driven by utility and supported by vision. Just like the example of Moore’s law you cited, I see no reason to believe that this will change in the near future. The only question we must ask is, should the whole thing exist to serve its users or should it serve those whose interest’s conflict with this purpose? I support the users and expect the others to realize that my time is as valuable, if not more, then the others interests.



  13. Hi All,

    I tried zero as answer and got thru it in a second... (thrice)


  14. That's a 'joke-captcha' ofcourse.
    In real world it would be hacked in days, there is nothing impossible for matlab, isn't there? :-)
    However there is a good point in such a capthca - it aims to make users ucomfortable. Not spamers.
    Spamers use captcha recognizers or captcha bypass services located in third world countries.
    So my guess - smart guys should locate another way to stop spam.

  15. capcha uses pi now


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