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A Mathematical Proof Too Long To Check

mikejuk writes "Mathematicians have generally gotten over their unease with computer-assisted proofs. But in the case of a new proof from researchers at the University of Liverpool, we may have crossed a line. The proof is currently contained within a 13 GB file — more space than is required to hold the entirety of Wikipedia. Its size makes it unlikely that humans will be able to check and confirm the proof. The theorem that has been proved is in connection with a long running conjecture of Paul Erdos in 1930. Discrepancy theory is about how possible it is to distribute something evenly. It occurs in lots of different forms and even has a connection with cryptography. In 1993 it was proved that an infinite series cannot have a discrepancy of 1 or less. This proved the theorem for C=1. The recent progress, which pushes C up to 2, was made possible by a clever idea of using a SAT solver — a program that finds values that make an expression true. Things went well up to length 1160, which was proved to have discrepancy 2, but at length 1161 the SAT returned the result that there was no assignment. The negative result generated an unsatisfiability certificate: the proof that a sequence of length 1161 has no subsequence with discrepancy 2 requires over 13 gigabytes of data. As the authors of the paper write: '[it]...is probably one of longest proofs of a non-trivial mathematical result ever produced. ... one may have doubts about to which degree this can be accepted as a proof of a mathematical statement.' Does this matter? Probably not — as long as other programs can check the result and the program itself has to be considered part of the proof."

189 comments

  1. To long, didn't check. by fleabay · · Score: 5, Funny

    TL;DC

    1. Re:To long, didn't check. by fleabay · · Score: 2, Funny

      Opps, "too long, didn't check." I guess I should have checked.

    2. Re:To long, didn't check. by Garridan · · Score: 5, Informative

      Funny thing about this. They've checked it. Actually, their "check" of this proof is many of orders of magnitude more rigorous than when, for example, a reviewer "checks" a math paper for errors before firing off a positive review. Nondisclaimer: I'm a mathematician.

    3. Re:To long, didn't check. by K.+S.+Kyosuke · · Score: 3, Informative

      My understanding is that checking an output of a proof assistant/generator is a trivial matter (i.e., a trained monkey should be able to do it). It's just that it's a lot of data even for the most patient humans in this case.

      --
      Ezekiel 23:20
    4. Re:To long, didn't check. by SydShamino · · Score: 4, Funny

      The neat part is that, if you take the first bit of each byte of the proof and string them all together, you get a complete HD MPEG copy of The Matrix.

      --
      It doesn't hurt to be nice.
    5. Re:To long, didn't check. by Garridan · · Score: 5, Insightful

      Mathematicians are supposed to be able to think at a higher level of abstraction than most other folks. Any mathematician who claims that 'this is too much for a human to check' is an idiot. It's not too much. We understand how computers work. They're way less error-prone than humans.

      1) Verify the proof that the verification algorithm works.
      2) Obtain several independent simple, portable implementations of said verification.
      3) Run said implementations on proof certificate on a variety of hardware.

      Trust the math, and where it comes to the hardware and software, trust but verify. Too long to check without aid of a computer? Sure, I'll buy that. But you'd have to be an idiot to want to check this proof without a computer. Why is this news? (actually, the result in discrepancy theory is wonderful, and I'm very happy to see it here on Slashdot... but massive computer proofs are truly nothing new)

    6. Re:To long, didn't check. by maxwell+demon · · Score: 1

      Opps, "too long, didn't check." I guess I should have checked.

      ITYM: Oops ...

      SCNR

      --
      The Tao of math: The numbers you can count are not the real numbers.
    7. Re:To long, didn't check. by maxwell+demon · · Score: 1

      Who says it must be checked by a single human? In the extreme, each single step could be verified by a different human. And that even in parallel.

      And even if it takes a century for humans to check that proof, it doesn't mean it's impossible. Unless we have a conclusive proof that humanity will not last that long.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    8. Re:To long, didn't check. by maxwell+demon · · Score: 5, Funny

      So you say the real reason why they cannot check the proof is that they would violate the DMCA by doing so?

      --
      The Tao of math: The numbers you can count are not the real numbers.
    9. Re:To long, didn't check. by BronsCon · · Score: 3, Funny

      Or, considering the value of C... "Two long, didn't check" may be just as appropriate.

      --
      APK quotes people (including myself) without context and should not be trusted. Just thought you should know.
    10. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      Automated rigorous checking of long proof logs isn't new. It's been done for years in academia and is used in commercial tools like this: http://www.prover.com/products/prover_certifier/

    11. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      And even if it takes a century for humans to check that proof, it doesn't mean it's impossible. Unless we have a conclusive proof that humanity will not last that long.

      Or that you suspect that one of the humans involved was sloppy or incompetent.
      Proof isn't proof if you can't trust it.

    12. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      On the contrary. If the proof is false, then it is enough to exhibit a single counterexample. No need to use a computer to find it, for values of $Mathematician which are sufficiently smart.

    13. Re:To long, didn't check. by maxwell+demon · · Score: 1

      You can easily counteract this by assigning the same part to several humans and comparing the results.

      Anyway, with shorter proofs, you generally have to trust other humans as well. Nobody has the time to check every proof himself. And how can you be sure that you can trust yourself? You might have learned something wrong, and thus unknowingly applying erroneous rules.

      Also, even if you manage to get the proof down to the set axioms, and check every single step yourself, there's still the possibility that the set axioms are contradictory.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    14. Re:To long, didn't check. by Garridan · · Score: 2

      You're the imaginative one, aren't you? Distributed proofs tend to duplicate work -- at least k contributors prove every claim, and each contributor should have some portion (maybe log(# contributions) or so, IIRC) of their work double-checked by an expert. Sure, it takes k times longer, but you can design it to take advantage of statistics to certify the proof more trustworthy than the average math paper.

      I wish modern mathematicians believed the math that they prove day after day for undergrads. If they did, this wouldn't be controversial.

    15. Re:To long, didn't check. by firewrought · · Score: 3, Informative

      But you'd have to be an idiot to want to check this proof without a computer.

      Historically, mathematicians have resisted computer-only proofs. They want eyeballs end-to-end. Your ideas (independent implementations, hardware, etc.) are sound/feasible from a software engineering standpoint, but unsatisfying to mathematicians. (Not being a mathematician myself, I'm ill-suited to testify as to why that's the case, but so it is.)

      Maybe one day that mindset will be abandoned, but what's more likely to happen is that mathematics will bifurcate: there will be the set of mathematics that relies on computer proofs and the "pure" subset of that that doesn't require computers. Probably, that's already considered the case. Regardless, this is how the field has dealt with countless other issues (such as not accepting negative proofs), often to great fecundity.

      --
      -1, Too Many Layers Of Abstraction
    16. Re:To long, didn't check. by Frobnicator · · Score: 1

      Doesn't seem any worse than a Zero Knowledge Proof system.

      Even if we cannot prove it formally, systems like this can put together a system with a very high probability of being correct if we simply test their results. If you can get multiple automated proof systems to claim it is impossible, and you trust the automated proof systems with a moderate degree of certainty, you can trust the results with about the same certainty.

      For many problems, having something "statistically proven" is good enough.

      --
      //TODO: Think of witty sig statement
    17. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      Perhaps you missed Garridan's original statement: "Nondisclaimer: I'm a mathematician."

      I think he knows a *bit* more than you about what is "unsatisfying to mathematicians".

    18. Re:To long, didn't check. by antdude · · Score: 1

      To?

      I read TL;DC as "too long, don't care". :P

      --
      Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
    19. Re:To long, didn't check. by Anonymous Coward · · Score: 1

      Given that this is a problem associated with Erdos, it is perhaps worth mentioning his views on the matter. Erdos believed in "the Book" - the book of all mathematically true theorems and their most elegant proof. A proof that is this size is by definition inelegant. Upon finding an inelegant proof, his response was, "Good, now find the book proof."

    20. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      Computers may be less error prone than humans, but _proving_ that a computer program is bug free (i.e. the solver) is far from trivial.

      Also, humans wrote the program.

      All of you people who want computers to drive cars, fly airplanes, and proof a mathematical theorem... are any of you actual computer programmers? You all talk as-if computers _replace_ humans in these situations, which is just... so... utterly wrong. Conversely, a bunch of human-piloted cars isn't simply a bunch of people moving steel boxes; all of their collective decisions and reactions create a complex, dynamic system which is something far more sophisticated than some idiot slamming a gas pedal.

    21. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      I wonder what this means for NSA data de-duplication algorithms?

    22. Re:To long, didn't check. by Nefarious+Wheel · · Score: 2

      Er.
      If the program that checks the proof is considered part of the proof, isn't that one of those recursive situations that Kurt Godel warned us about, as popularised in Hofstadter's GEB?

      --
      Do not mock my vision of impractical footwear
    23. Re:To long, didn't check. by Thanshin · · Score: 1

      My understanding is that checking an output of a proof assistant/generator is a trivial matter (i.e., a trained monkey should be able to do it).

      That's not much of a standard. A trained monkey could also write the entire works of Shakespeare*.

      *: As long as you had enough of them**.

      **: Monkeys, not Shakespeares. If you had infinite Shakespeares I guess they could peal a banana, or something.

    24. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      Well, my doctor has opinions about health that are wrong. Him saying "I'm a doctor" doesn't change that.

    25. Re:To long, didn't check. by hawkinspeter · · Score: 1

      Godel prooved, however, that there are plenty of true statements that cannot be prooved.

      --
      You're a temporary arrangement of matter sliding towards oblivion in a cold, uncaring universe
    26. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      Intuitionists accept negative proofs, and in fact accept proofs by contradiction if and only if a direct proof exists.

    27. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      Yes, doctors can make mistakes about medicine. Although if you are going to talk about what is "satisfying" or "unsatisfying" to doctors, then right or wrong, an actual doctor might have a bit more to say about what doctors' opinions.

    28. Re:To long, didn't check. by Anonymous Coward · · Score: 0

      Then their most elegant proof is infinitely long. Duh.

    29. Re:To long, didn't check. by Garridan · · Score: 1

      I'll undermine your 'proof by authority' by pointing out that the best you can possibly get from my assertion is a fallacy of false generalization. In fact, I'll go so far as to say that GP is correct. Some mathematicians are unsatisfied by computer proofs. Possibly most mathematicians. I've apparently gone on record calling the majority of mathematicians "idiots". Worse, I'm on the job market. Good thing my real name isn't on this account!

      If I get tenure, I'll get to put my name to my opinions. If I'm a tenth as cranky and outspoken as Doron Zeilberger, I'll be satisfied.

    30. Re:To long, didn't check. by Garridan · · Score: 1

      No. The program does not check itself. You rely on faulty humans for that part. Duh. There's gotta be some fault in the rigor or you'll never get your math paper published.

    31. Re:To long, didn't check. by Pseudonym · · Score: 1

      Coq and Isabelle are far better choices, being better supported and open source. And if you need their credentials, there is a Coq-checked proof of the four colour theorem, and an Isabelle proof that the L4 kernel is secure.

      --
      sub f{($f)=@_;print"$f(q{$f});";}f(q{sub f{($f)=@_;print"$f(q{$f});";}f});
    32. Re:To long, didn't check. by Pseudonym · · Score: 1

      Not exactly. Machine-checkable outputs tend to come in one of two varieties: certificates (of which this is an example, since it's an UNSAT certificate) and proofs proper.

      Proofs (which are the sort of things you'd feed to Coq or Isabelle) tend to rely heavily on built-in tactics. There are some theories (classical logic, intuitionistic logic, Presburger arithmetic, Tarski arithmetic, etc) which are known to be decidable, but the decision procedures are beyond most humans, let alone trained monkeys. For example, in Tarski arithmetic, you might be faced with the following goal:

            a : R, b : R, c : R |- exists x : R, a*x*x + b*x + c = 0

      (Translation into high-school-level maths: If a, b, and c are real numbers, then the equation ax^2 + bx + c = 0 has a real root.)

      You apply the "eliminate the existential quantifier" tactic, and it will give you a new goal which represents the necessary and sufficient conditions for this goal to be true:

            a : R, b : R, c : R |- (a = 0 /\ b = 0 /\ c = 0) \/ (a = 0 /\ b 0) \/ (b*b >= 4*a*c)

      (Translation into high-school-level maths: Either a, b and c are all zero, or the equation is really linear and nondegenerate, or the determinant is greater than or equal to zero. Yes, this result was really found automatically by a Tarski arithmetic solver.)

      That's one "step" in a machine-checked proof. Most humans are not able to get the nondegeneracy conditions correct, and asking a trained monkey to do it is unreasonable.

      The other type of check is a certificate. Certificates are technically proofs, but they are are typically highly domain-specific descriptions based the problem at hand, as opposed to a general statement in logic-plus-theories. Certificates for UNSAT, for example, tend to be based around a set of choices that a SAT solver would have to make to verify that the problem fails SAT.

      --
      sub f{($f)=@_;print"$f(q{$f});";}f(q{sub f{($f)=@_;print"$f(q{$f});";}f});
  2. News for nerds by dysmal · · Score: 0

    Don't a lot most of what's said which is why i'm interested in this!

    1. Re:News for nerds by cheater512 · · Score: 1

      Oh its really quite simple.....once you've learned basic English.

      Keep at it. I'm sure you'll get there eventually.

  3. wow by Anonymous Coward · · Score: 5, Insightful

    less space than wikipedia? that sounds large.

    wtf?

    1. Re:wow by HaZardman27 · · Score: 5, Funny

      I guess we've moved on from using "Libraries of Congress" as a unit of data size. I wonder how many "less than Wikipedia"s worth of data the NSA has?

      --
      Apparently wizard is not a legitimate career path, so I chose programmer instead.
    2. Re:wow by EvilSS · · Score: 1

      less space than wikipedia? that sounds large.

      wtf?

      Yea, checking TFA it appears this is a case of less = more.

      --
      I browse on +1 so AC's need not respond, I won't see it.
    3. Re:wow by Anonymous Coward · · Score: 0

      The proof that 1=1 also takes "less space than is required to hold the entirety of Wikipedia"

    4. Re:wow by gnick · · Score: 1

      We're getting to a point where, "Can I store it on a card smaller than my pinky nail?" has replaced "Libraries of Congress."

      --
      He's getting rather old, but he's a good mouse.
    5. Re:wow by Nexus7 · · Score: 3, Insightful

      I think they meant to say "less space than that is required to store Wikipedia".

    6. Re:wow by Anonymous Coward · · Score: 0

      I thought it was Volkswagens for a while. All these changes in measurement make me wish for the good old days when we used cubits.

    7. Re:wow by SJHillman · · Score: 1

      I always measured in station wagons. Maybe that's the American equivalent of a Volkswagen.

    8. Re:wow by tsqr · · Score: 1, Insightful

      I think they meant to say "less space than that is required to store Wikipedia".

      Probably not. Since 0 bytes is less space than that is required to store Wikipedia, I would wager that they actually meant to say, "more space than that is required to store Wikipedia.

    9. Re:wow by Anonymous Coward · · Score: 1

      1=1 does not require a proof because it is an axiom, also known as a formalized assumption. This is sometimes referred to as the Identity Axiom.

    10. Re:wow by Anonymous Coward · · Score: 0

      And even 0 space is less than required to store wikipedia.

    11. Re:wow by egcagrac0 · · Score: 3, Insightful

      AFAIK, a "standard" LoC is 10TB... around 769 times larger than this file. Comparing this to an LoC is technically valid, but not particularly useful for the typical reader.

    12. Re:wow by Anonymous Coward · · Score: 1

      Depends on what set of axioms you pick as your base set, and some common choices don't have have that as an axiom because it is (easily) provable from a more basic set of axioms. For example, using something similar to Tarski's set of predicate calculus axioms requires something like 9 steps if being explicit.

    13. Re:wow by Garridan · · Score: 1

      Maybe out in Granola Country. Where I'm from, we measure in Hummers.

    14. Re:wow by maxwell+demon · · Score: 1

      I thought it was Volkswagens for a while. All these changes in measurement make me wish for the good old days when we used cubits.

      Don't worry, when we have quantum computers on our desks, we will use qubits. Almost the same as cubits, isn't it? ;-)

      --
      The Tao of math: The numbers you can count are not the real numbers.
    15. Re:wow by pablo.cl · · Score: 2

      It depends if you stress "that" or not.

      1) "less space than *that*, is required to store Wikipedia"

      2) "less space than that is required to store Wikipedia" = "less space than what is required to store Wikipedia"

    16. Re:wow by RendonWI · · Score: 1

      I think the NSA has -4 LTW's of data.

    17. Re:wow by tsqr · · Score: 1

      It depends if you stress "that" or not.

      What you say would be true, if the word "that" had appeared in the original summary; however, it didn't. Here's the original wording: "The proof is currently contained within a 13 GB file — less space than is required to hold the entirety of Wikipedia." Nothing to stress or interpret there, although I will grant you that the inappropriate use of the emdash does confuse matters a bit.

      I suppose it's all moot now anyway, since the summary has been edited to protect the guilty and to correct the mistake -- it now says "The proof is currently contained within a 13 GB file — more space than is required to hold the entirety of Wikipedia."

    18. Re:wow by Anonymous Coward · · Score: 0

      The hummer is the standard unit of your mom.

    19. Re:wow by Anonymous Coward · · Score: 0

      less space than wikipedia? that sounds large.

      wtf?

      WTF indeed. Nobody is asking the more pertinent question "Why exactly is the file 13 gigs"? Is it it 13 gigs worth of compressed ascii, or 13gigs worth of uncompressed, unreasonable hi-resolution images? Measuring a proof by the size of the storage file really isn't all that meaningful. In addition, it's quite likely that large sections of the overall proof are already well-known and proven "proofs" themselves.

      For a programmer analogy, it could very well be like writing a "hello, world" program that includes a standard library. If you're going to review the source code to find a bug, you don't actually need to check the entire library just the extra bits.

      Shrug. I'll leave this to the Math guys to decide if it's "too long to check" or not. Besides, eventually some autistic kid will come along and check the damn thing while he eats his breakfast. Twice.

    20. Re:wow by Anonymous Coward · · Score: 0

      Wikipedia is currently under 10GB *compressed* (excluding article history and talk pages)
      Uncompressed it is 43GB.

      An uninformed comparison? Sure. But still "1/3rd of Wikipedia" is still large.

    21. Re:wow by Anonymous Coward · · Score: 0

      If you lay out all the pages side-by-side, there are about 80 Libraries of Congress in the size of Wales.

    22. Re:wow by Howitzer86 · · Score: 1

      I wonder about the usefulness of a unit of measure that constantly changes. Perhaps we should also consider storing the Library of Congress inside of a temperature controlled, airless chamber. We could then store this unit in the Library of Congress for further refere-

      Unhandled exception at 0x00435917 in Howitzer86.exe: | 0xC00000FD: Stack overflow.

  4. Computer Certified! (TM) by Anonymous Coward · · Score: 0

    This proof has been Computer Certified to be 100% correct and complete. That's all I need to see to believe it. Now I'll just turn in my homework to my mathematics prof on the portable hard drive.

  5. the beginning, not the end by EngineeringStudent · · Score: 5, Interesting

    it is the beginning of AI-science, not the end of human science.

    Science requires testable, provable, repeatable. If a human cannot understand the proof then he cannot participate in the science. This is likely to be referred to as an "early" version of machine-exclusive science.

    1. Re:the beginning, not the end by Anonymous Coward · · Score: 0

      Why can't we get thousands of mathematicians to take on a part of the proof and check it that way? Or is that impossible?

    2. Re:the beginning, not the end by Kufat · · Score: 5, Insightful

      I'd hesitate to call one big for loop "AI." The interesting part of the proof is the reduction to SAT, and that's easily understood by mathematicians. The computer part is a straightforward and dull brute force search.

    3. Re:the beginning, not the end by Anonymous Coward · · Score: 2, Informative

      It's far from the beginning. That would be in 1976 with the computer proof of the four color theorem, which was the original controversy over proofs only checkable by a computer. The 13GB proof is certainly huge, but proofs that a human can't check aren't new. I don't know how it is in mathematics, but in programming languages research, any proof that isn't computer-checked is suspect because humans are just really bad at being completely consistent at long repetitive processes like checking proofs.

    4. Re:the beginning, not the end by Anonymous Coward · · Score: 0

      The computer part is a straightforward and dull brute force search.

      Yes and no. The optimizations that most SAT solvers use to find truth conditions are impressive. However, to show a false condition, it is required to try everything.

    5. Re:the beginning, not the end by DriedClexler · · Score: 1

      Agree in principle, but I'm not sure this fails that standard to the extent that it's relevant for science to work. Sure, a human may not directly understand the entire proof. However, like with the Four Color Theorem, they can verify:

      - A proof checker would catch errors if there were any, and has failed to.
      - The thing it purports to prove is in fact (a representation) of the theorem the submitter claims to have proven.
      - The proof generator generates only valid steps.

      Could there be errors in the process? Sure. But it's definitely something that humans can do science with.

      --
      Information theory is life. The rest is just the KL divergence.
    6. Re:the beginning, not the end by maxwell+demon · · Score: 2

      I'd hesitate to call one big for loop "AI."

      So you would more readily accept a big while loop as AI? ;-)

      --
      The Tao of math: The numbers you can count are not the real numbers.
  6. After 9.5gigs by jellomizer · · Score: 5, Funny

    In the results there is the following statement.
    "As any idiot can plainly see"

    --
    If something is so important that you feel the need to post it on the internet... It probably isn't that important.
    1. Re:After 9.5gigs by Trax3001BBS · · Score: 1

      In the results there is the following statement.
      "As any idiot can plainly see"

      LOL!
      no, I didn't rta.

    2. Re:After 9.5gigs by QilessQi · · Score: 4, Funny

      I have it on good authority that one of the steps of the proof is "???", followed by "PROFIT!".

    3. Re:After 9.5gigs by maxwell+demon · · Score: 2

      Actually it contains the step "then a miracle occurs."

      --
      The Tao of math: The numbers you can count are not the real numbers.
    4. Re:After 9.5gigs by Anonymous Coward · · Score: 0

      Welcome to high school mathematics lecture!

    5. Re:After 9.5gigs by quenda · · Score: 2

      Actually it is worse.
      When somebody finally got around to looking at the 9.5GB proof, it started like this:

      All work and no play makes HAL a dull program.
      All work and no play makes HAL a dull program.
      All work and no play makes HAL a dull program.
      All work and no play makes HAL a dull program.
      All work and no play makes HAL a dull program.

      ...

    6. Re:After 9.5gigs by ebvwfbw · · Score: 1

      In the results there is the following statement.
      "As any idiot can plainly see"

      They wouldn't say that. Now if you wrote "... Obviously we have...." or "clearly it follows" I remember the first time I said to a student - Nope, it isn't obvious. Explain. Deer in headlights look. WHaaaaaa?

  7. Paging Mr Fermat... by UdoKeir · · Score: 5, Funny

    I have discovered a truly marvellous proof of this, which this DVD is too small to contain.

    1. Re:Paging Mr Fermat... by Anonymous Coward · · Score: 0

      Must ... get ... NSA ... storage ... array.

  8. the computer's always right and other such quaint by Anonymous Coward · · Score: 0

    hey matermerticians : GIGO

  9. Grad students? by EvilSS · · Score: 5, Funny

    "Its size makes it unlikely that humans will be able to check and confirm the proof."

    I thought that's what grad students were for: endless mind-numbing labor. "Here, check this and have it back to me in 30 years or so."

    --
    I browse on +1 so AC's need not respond, I won't see it.
  10. Say, what? by Anna+Merikin · · Score: 0

    Sounds like a bad idea to me, a civilian. It reminds me of the old saw about the man who "knows nearly everything about almost nothing."

    Unless world population continues to rise exponentially, I fear this proof is doomed to oblivion for lack of anyone who cares and has the ability to check it.

    1. Re:Say, what? by gtall · · Score: 1

      You presume the proof has unique steps at every point. It doesn't, if something couldn't be found in a random sequence of 1161 numbers, then it couldn't be found in an infinite sequence (my apologies for paraphrasing, go read the article). So they used a computer to check the 1161 numbers. So they essentially had a for loop. The code for the for loop was finite. The loop was finite. A few invariants and a bit of Floyd-Hoare logic and whallah, the proof be checked, just not the usual way you'd expect.

    2. Re:Say, what? by lgw · · Score: 1

      "whallah"? Really?

      --
      Socialism: a lie told by totalitarians and believed by fools.
    3. Re:Say, what? by Anonymous Coward · · Score: 1

      As a mathematician, the length of the certificate is the least interesting thing about this. 13G isn't big for a computer, 13K would be far too large for a human to check by hand, so this is not in any essential way different from any other proof using computer calculation.

      The problem itself is fascinating, though; the N = 1 case is small enough to do by hand (I get 11 as the length of the longest sequence with no discrepancy greater than 1). Strange that they seem to think the N = 3 result may be less than 20000.

  11. Can't have your pi and eat it too, by Trax3001BBS · · Score: 1

    Just saying.

  12. Less space than Wikipedia by BlueMonk · · Score: 5, Insightful

    less space than is required to hold the entirety of Wikipedia

    I'd venture a guess that this is not unique and that every mathematical proof to date takes less space than Wikipedia. Did they mean more space?

    1. Re:Less space than Wikipedia by Anonymous Coward · · Score: 0

      No, I think the poster has it correct. It is very difficult to read otherwise

    2. Re:Less space than Wikipedia by Anonymous Coward · · Score: 1

      No, I think they are saying that Wikipedia is more than 13 GB but that the amount of space this proof requires is comparable to the amount of space stored by Wikipedia even though it needs less space.

      (skipping car analogy).

      It's like saying that our star is smaller or bigger than another star (insert star name here). The comparison is a fair one. But saying that the (planet or whatever it's called now) Pluto is smaller than the sun is a pointless statement. Or saying that the Earth is smaller than the sun. Saying that Mercury is smaller than Earth makes sense.

      For instance, if the proof were a megabyte then there is no point in saying that the file is smaller than Wikipedia because a megabyte is not large enough to meaningfully compare it to Wikipedia by analogy.

    3. Re:Less space than Wikipedia by BlueMonk · · Score: 1
      I suspect they missed a "that".

      less space than that is required to hold the entirety of Wikipedia.

    4. Re:Less space than Wikipedia by roninmagus · · Score: 2

      I think this is a failure of editing. WIkipedia's database is 9gb compressed and 44gb uncompressed. (source: http://en.wikipedia.org/wiki/W...) The statement that it is less than Wikipedia's database is a useless comparison.

  13. "Less space ... to hold ... Wikipedia"?!?!? by Anonymous Coward · · Score: 1

    less space than is required to hold the entirety of Wikipedia

    WTF? Editor! Where's the EDITOR?

    1. Re:"Less space ... to hold ... Wikipedia"?!?!? by Anonymous Coward · · Score: 2, Funny

      Editor? This is Slashdot.

    2. Re:"Less space ... to hold ... Wikipedia"?!?!? by Anonymous Coward · · Score: 0

      Editor? This is Slashdot.

      You forgot to finish with the kick into the pit of death.

  14. Very fi by Impy+the+Impiuos+Imp · · Score: 1

    One trick is to use a completely different algorithm to generate it, if that is possible. I've done that many times in the past and they end up debugging each other. When they can churn for days always spitting ot identical results, you gain confidence.

    --
    (-1: Post disagrees with my already-settled worldview) is not a valid mod option.
  15. prove that the program works by Khashishi · · Score: 1

    I don't see why you need to go through the fuss of the 13 GB file. What was the algorithm used to make the file? Prove that the algorithm works. That's your proof. (Run the program a few times, so the probability of errors in the output is close to zero. Remember that the probability of the computer making a mistake (cosmic rays, transistor noise, etc) is smaller than the probability of a human mathematician making a mistake.)

    1. Re:prove that the program works by cdrudge · · Score: 1

      Run the program a few times, so the probability of errors in the output is close to zero.

      No. If it's indeed a proof the probability of errors must be 0, not just close to it.

    2. Re:prove that the program works by Anonymous Coward · · Score: 0

      That's not maths. We don't accept "the probability of this being wrong is close to zero" as proof - proof has to be absolute. So the only way that you could get this past a real mathematician would be to run the computer program an infinite number of times and find that at that limit the probability you were wrong was exactly zero. Maths doesn't submit to the scientific method. Mathematical proof is done through logic (induction, reducto ad absurdum etc) not experiment.

    3. Re:prove that the program works by ThanatosMinor · · Score: 1

      Prove that the algorithm works. That's your proof.

      Gödel and Turing make strong cases that proving the algorithm works for some inputs that are correct proofs doesn't count as proof it will work for all correct proof inputs. So no, even if you "prove the algorithm works" it is not the same as a rigorous mathematical proof.

    4. Re:prove that the program works by ThanatosMinor · · Score: 1

      Forgot to mention those guys showed that such an algorithm that "works" for all valid proofs is not just difficult but mathematically impossible.

    5. Re:prove that the program works by Anonymous Coward · · Score: 1

      If you prove the algorithm works, you prove it for all inputs.

    6. Re:prove that the program works by Anonymous Coward · · Score: 0

      Remember that the probability of the computer making a mistake (cosmic rays, transistor noise, etc) is smaller than the probability of a human mathematician making a mistake.

      True dat!

      Human Mathematician

    7. Re:prove that the program works by ClickOnThis · · Score: 5, Informative

      Prove that the algorithm works. That's your proof.

      Gödel and Turing make strong cases that proving the algorithm works for some inputs that are correct proofs doesn't count as proof it will work for all correct proof inputs. So no, even if you "prove the algorithm works" it is not the same as a rigorous mathematical proof.

      You're comparing apples to oranges (and lemons.)

      If the algorithm can be proved correct (within whatever axiomatic system you're using) then it's correct. The End.

      Gödel's incompleteness theorem shows that certain statements about axiomatic systems can be true but cannot be proved. That doesn't mean you can't be certain of something that is in fact proved (subject of course to the axioms.)

      Turing's halting problem is a statement about limitations in the ability of algorithms to examine other algorithms. Again, it doesn't mean you can't prove that an algorithm is correct.

      --
      If it weren't for deadlines, nothing would be late.
    8. Re:prove that the program works by Anonymous Coward · · Score: 0

      The poster is not suggesting experimentation.

      Consider using a computer to prove that 2+2 = 4
      It could be done in the following way.
      1) Add 2 + 2
      2) Check if the result is 4
      Will this procedure work? Normally, yes. If you research some of the terms in the post you replied too, you’ll learn that sometimes outside influences cause digital circuits to output wrong results. As transistor sizes has decreased the danger of such things have increased and so has the research in preventing them. Looks like the poster is concerned enough with such a possibility as to want the calculation repeated to guard against the result being caused by a single event upset or similar.

    9. Re:prove that the program works by tepples · · Score: 1

      First prove, with a zero probability of errors, that the world you live in is the real world as opposed to a simulation performing a Sybil attack through all five senses.

    10. Re:prove that the program works by weilawei · · Score: 2

      Proof is absolute, within the confines of the accepted axioms. Within the larger scope of things, we accept proof probabilistically, and this includes the entire works of every mathematician ever to live. Bayesian stats attempts to capture this idea that knowledge is never absolute, but merely held with probabilistic certainty, and all things are based on axioms (inherently unprovable, but assumed to be useful) ultimately. I only gripe (and boy is it a really fine, pedantic gripe), because your comment commits the same error you attack. Math/logic is a model, not reality. Models are based on necessary assumptions (axioms), otherwise you'd be arguing with solipsists over every detail, no matter how blindingly "obvious". This trend toward claiming that a mathematical proof or a scientific theory is "absolute" violates the very premise on which they're based.

    11. Re:prove that the program works by sexconker · · Score: 2

      Run the program a few times, so the probability of errors in the output is close to zero.

      No. If it's indeed a proof the probability of errors must be 0, not just close to it.

      He's referring to errors during runtime (electrical noise, bit flips, not enough spiders in the case, etc.), not errors in the logic.
      If the generator's logic is provably correct, then the things it generates are as well as long as your hardware it working properly. There is no way to rigorously prove hardware works correctly for all input strings, for all time, for all environmental conditions, across all variations due to manufacturing, etc.

    12. Re:prove that the program works by weilawei · · Score: 1

      If the algorithm can be proved correct (within whatever axiomatic system you're using) then it's correct. The End.

      Thank you. For the love of FSM, thank you for qualifying your statement about proof.

    13. Re:prove that the program works by ThanatosMinor · · Score: 1
      I think the issue here stems from the concept of "correct" and how knowable that value is.

      Turing's halting problem is a statement about limitations in the ability of algorithms to examine other algorithms. Again, it doesn't mean you can't prove that an algorithm is correct, no matter how "correct" the algorithm appears.

      That's kind of my point. Given this proof, it would show that the algorithm is incorrect if the proof is shown to be invalid, yet the proof is too long to be verified by anything but another algorithm, so the halting problem is definitely relevant in a discussion about algorithm-generated proofs which can't be verified by humans.

      Sure, if errors are found in a generating algorithm, then they will be fixed and it will be run again, but that again doesn't show that its "proof" is a real proof without independent verification, which again invokes the halting problem if its proof is horrendously long since what it creates must be evaluated by another algorithm. There is no way to demonstrate that such an algorithm as this generates only correct proofs.

      Yes, some proofs can be generated by algorithms and others can be checked by algorithms, but a mathematician is necessary at some point in the process since no non-trivial generating algorithm can be shown to create only correct proofs and no universal checking algorithm can be created which generates no false positives or negatives.

      Considering how complex computer systems are, is it even possible to claim that an algorithm can run bug-free enough to consider correctness of code equivalent to verification that its output is correct in any but trivial cases?

    14. Re:prove that the program works by Your.Master · · Score: 1

      Re-running the program is equivalent to having more than one mathematician review the proof. In both cases, you're trying to drive the probability of error in verification down to zero.

    15. Re:prove that the program works by ThanatosMinor · · Score: 1

      Note also the poster I responded to didn't say prove the algorithm is correct and error-free, but rather that it "works," which means generates a correct proof, the checking of which (probably) invokes the halting problem. I say probably because it's likely no easier to write an algorithm that is designed specifically to check this "proof" for correctness than it is for a mathematician to verify it manually, and therefore it would be verified by a general one designed to verify proofs. The halting problem doesn't apply to the former case since it would involve a single-use algorithm to verify one single input, but it surely applies to the latter.

    16. Re:prove that the program works by lgw · · Score: 1

      There's not really any such thing as "provably correct logic" to begin with. A some point you just have to decide that the chance of errors across the process is low enough to go on with. I think of this as the "certainty noise floor": it's not important whether the chance of error is 0, but that the chance is really quite small, because that's the best we ever get.

      --
      Socialism: a lie told by totalitarians and believed by fools.
    17. Re:prove that the program works by lgw · · Score: 1

      Proof is absolute, within the confines of the accepted axioms.

      No, not really. Or perhaps I should say: one can never be absolutely certain that a proof is correct. Practically the flaws in the model (when the model is just math) are so small compared to likely flaws in the modeling that it's best to ignore them, but even in the abstract there is no "absolute proof".

      --
      Socialism: a lie told by totalitarians and believed by fools.
    18. Re:prove that the program works by ClickOnThis · · Score: 3, Insightful

      I think the issue here stems from the concept of "correct" and how knowable that value is.

      Turing's halting problem is a statement about limitations in the ability of algorithms to examine other algorithms. Again, it doesn't mean you can't prove that an algorithm is correct, no matter how "correct" the algorithm appears.

      Um, excuse me. If you're going to quote me and change what I said, then indicate your edits. I have done so above, in bold. Not that I can make sense of them.

      That's kind of my point. Given this proof, it would show that the algorithm is incorrect if the proof is shown to be invalid

      Wha...? That's just plain wrong. I can think up all kinds of invalid proofs of the Pythagorean Theorem. But showing that a proof is invalid does not mean the theorem is incorrect. It just means your proof is.

      yet the proof is too long to be verified by anything but another algorithm, so the halting problem is definitely relevant in a discussion about algorithm-generated proofs which can't be verified by humans.

      Again, Turing's halting problem illustrates limitations on the ability of algorithms to decide certain propositions. It does not mean that algorithms can't decide anything. You seem to think that it does.

      Yes, some proofs can be generated by algorithms and others can be checked by algorithms, but a mathematician is necessary at some point in the process since no non-trivial generating algorithm can be shown to create only correct proofs and no universal checking algorithm can be created which generates no false positives or negatives.

      Your fallacy is that one cannot trust specific algorithms to prove things because no such universal algorithm can be created.

      --
      If it weren't for deadlines, nothing would be late.
    19. Re:prove that the program works by DMUTPeregrine · · Score: 1

      Both are also general case statements. There are many, many programs which can be proven to halt or to loop indefinitely quite easily. The trick is that you can't create a program which, when given ANY program as input determines whether it will halt. Your program may well work for billions of programs, but there is at least one program for which it must fail. (Actually, there are infinitely many programs for which it must fail, but they're sparse in the space of all possible programs...)

      --
      Not a sentence!
    20. Re:prove that the program works by Anonymous Coward · · Score: 0

      Exactly, we are comfortable with using arguments that contemplate an infinity of infinite cardinalities and yet we stumble with a mere finite string?

    21. Re:prove that the program works by Anonymous Coward · · Score: 0

      one can never be absolutely certain that a proof is correct.

      The proof itself is absolute within its own axiomatic system; whether an entity is able to verify it or not is irrelevant to the correctness of the proof. If it isn't correct, it isn't a proof, just something which someone claimed to be a proof. Just like the universe does not require a human to elaborate on the horseness of a horse in order for said horse to exist. This does NOT mean that humans can demonstrate, in an absolute fashion, that the proof is correct. If you've got a counter-example, let's hear it.

    22. Re:prove that the program works by lgw · · Score: 2

      The problem with this is that "axiomatic system" is an inadequate caveat. You also have to blindly assume that some specific system of deduction works. In practice, specific axioms are usually chosen based on the assumption that induction works, the basic unprovable assumption underlying all of science. But it's worse than that: you can't even prove that deduction works! (It's obvious in hindsight, really.)

      Any logical system simply asserts rules of deduction. Why use some particular rules of deduction over another? Worse: humanity only realized recently that no such system can be both consistent and complete. What else are we missing?

      So the best you can say is that a proof is or is not correct given arbitrary axioms and rules of deduction and we can't know in the general case whether a given proof is correct! Not much of a claim, really.

      --
      Socialism: a lie told by totalitarians and believed by fools.
    23. Re:prove that the program works by ThanatosMinor · · Score: 1

      Um, excuse me. If you're going to quote me and change what I said, then indicate your edits. I have done so above, in bold. Not that I can make sense of them.

      Sorry, I realized at one point I was editing the quote rather than my own text and thought I fixed it but apparently missed one of my edits and there's no reason it should make sense there. Entirely my fault.

      Wha...? That's just plain wrong. I can think up all kinds of invalid proofs of the Pythagorean Theorem. But showing that a proof is invalid does not mean the theorem is incorrect. It just means your proof is.

      Double wha...? I never claimed the theory behind the algorithm is incorrect, just that if an algorithm designed to produce correct proofs produces a fautly proof, the algorithm is faulty. If you think up an invalid proof of the Pythagorean Theorem, you're at fault for violating the rules of the system and I don't know why anyone would claim it's a fault of the system itself.

      As for the rest, please see my other reply to your first post, relating to specific vs. universal algorithms. The gist is that a specific algorithm can be written to check the validity of this proof, but doing so is functionally equivalent to manual verification, but a universal algorithm to verify all correct proofs is impossible.

      I never said that one couldn't produce either an algorithm that generates proofs or one that verifies proofs, but the fact is, since there exist true statements that are unprovable the latter algorithm cannot be universal. It can only check whether the symbols follow its understanding of the rules of manipulation.

      I get what you're saying. Since Program A can be written to conform to certain rules, Program B can be written to confirm the output of A conforms to the rules that A was given, so yes the proof can be "verified" that way, but by definition you're still only covering some of the proofs A might generate.

      But note that the poster I originally responded to said that the output need not be evaulated, but rather only the generating algorithm. I never even said this was a useless approach, since it will likely converge to a correct result, but it hardly counts as a proof of the result. Checking programming isn't the same as checking output, and checking output isn't the same as proving mathematical validity, though of course it can be the same as proving that what you get is what you expected to get, which may be good enough in many cases but wasn't even what I was originally responding to.

      It may be that I'm assigning too much power to the algorithm that generated the proof. While it's impossible to program an algorithm with the axioms of a system and tell it to generate all the valid proofs of the system, and equally impossible to similarly program one to verify all proofs of the system, some smaller tasks (maybe this one) are certainly within the realm of algorithmic possibility. I was thinking of the original poster's comment in a very general context and not just in that of this specific problem.

    24. Re:prove that the program works by weilawei · · Score: 1
      So, you're saying that the rules of production are axioms too. Still doesn't change what I said. But, you do arrive at the same endpoint that I arrived at, which is that if you don't accept some of them at some point, you'll wind up back at my original point.

      otherwise you'd be arguing with solipsists over every detail, no matter how blindingly "obvious"

      Anything new to add?

    25. Re:prove that the program works by Anonymous Coward · · Score: 0

      That's not maths. We don't accept "the probability of this being wrong is close to zero" as proof - proof has to be absolute. So the only way that you could get this past a real mathematician would be to run the computer program an infinite number of times and find that at that limit the probability you were wrong was exactly zero. Maths doesn't submit to the scientific method. Mathematical proof is done through logic (induction, reducto ad absurdum etc) not experiment.

      No. Mathematical proofs don't and never have used induction. You use deduction not induction.
      Induction is useful only in formulating conjectures, but a mathematical proof can't rely on induction.

    26. Re:prove that the program works by lgw · · Score: 1

      So, you're saying that the rules of production are axioms too. Still doesn't change what I said.

      Not that it changes your conclusion, but it's an important difference in kind. Axioms are just the assumptions of the model, and you can reject certain axioms without being a hardcore skeptic who doubts logic. The latter assumption - that deduction works - is an assumption often made by solipsists who won't grant the assumption that sense data is accurate, but never think to question their other assumptions. It's great fun to poke at the solipsist position that way!

      It's also a non-trivial realization: that it goes far beyond solipsism and that you can't have rationality without simply stipulating some stuff. As a philosophy prof once pointed out to me: if rationality isn't required, I'm free to make any assumptions I like, and so I'll make the assumptions required for rationality.

      --
      Socialism: a lie told by totalitarians and believed by fools.
    27. Re:prove that the program works by psmears · · Score: 1

      Prove that the algorithm works. That's your proof.

      Gödel and Turing make strong cases that proving the algorithm works for some inputs that are correct proofs doesn't count as proof it will work for all correct proof inputs. So no, even if you "prove the algorithm works" it is not the same as a rigorous mathematical proof.

      Not true - proving the algorithm works is the same as a rigorous mathematical proof, if you prove mathematically and rigorously that the algorithm works. (The comment about running the algorithm a number of times was simply to guard against the proven-correct algorithm producing a wrong result due to a machine malfunction.)

    28. Re:prove that the program works by psmears · · Score: 1

      Forgot to mention those guys showed that such an algorithm that "works" for all valid proofs is not just difficult but mathematically impossible.

      No, that's not actually what they proved; it is perfectly possible to prove a given algorithm works for all possible inputs, and even that a proof checker works for all valid proofs. There are certainly things that they proved impossible (e.g. a writing a program that can provide a proof for any true mathematical statement, or that can determine if two arbitrary programs are equivalent), but those don't apply here.

  16. that word does not mean what you think it means by SlashDread · · Score: 1

    " Prove that the algorithm works. That's your proof. (Run the program a few times, so the probability of errors in the output is close to zero"

    "probably true" is NOT a prove.

    1. Re:that word does not mean what you think it means by careysub · · Score: 1

      " Prove that the algorithm works. That's your proof. (Run the program a few times, so the probability of errors in the output is close to zero"

      "probably true" is NOT a prove.

      This isn't a probabilistic 'proof' - it is straight-up deterministic: the SAT result proves it true. Period.

      The poster above is alluding to the fact that a random software error could occur that gives the same result erroneously. Thus running the program is used to show that this isn't the case at all.

      To assert that a lengthy, complex mathematical proof entirely written by a human is absolutely true requires you to believe the human is incapable of error (Wile's proof of the FLT ran 150 pages and this is not exceptional). The probability that a proof-author and a few successive reviewers could miss a mistake is astronomically greater than the chance of multiple random computer error corrupting the SAT calculation.

      --
      Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
  17. Stay away from SAT solvers by Anonymous Coward · · Score: 1

    I don't trust solvers. I've tried several "state of the art" and "award winning" solvers only for them to throw up on test inputs intentionally designed to mess with them after realizing I was way over my head attempting to roll my own.

    Even working simple graphs expressed as a series of disjunctions A -> B -> C -> D (!A || B) && (!B || C) && (!C || D) yield garbage on a couple open source "crypto" branded solvers. I hope with the commercial solvers it is the case you get what you pay for... it seems the more exotic algorithms they use to beat NP the more fragile they become.

  18. Conclusion is good by gweihir · · Score: 1

    SAT solving is easy when there is a solution. When there is not, it gets very hard, as basically the solver enumerates all ways it could have found a proof and shows for each that it did not work. Still faster than a full exhaustive search (which is infeasible from, say 80 bits or so of problem space size). On the other hand, SAT solvers are not that complicated if you ignore implementation details. So the solver itself, together with the 1-bit answer "no" could be used as proof instead of the 13GB. My guess is that it will take some time for that to become accepted, but some mathematicians are pretty mentally agile and not opposed to use of modern tools at all.

    --
    Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
    1. Re:Conclusion is good by Anonymous Coward · · Score: 0

      Agreed, the interesting thing here is that he showed that there isn't a solution for a given number: 1161. If anyone cares to show him wrong, they just need to try everything on that number and see that nothing works.

  19. Assume that we have an infinite supply of mathemat by Anonymous Coward · · Score: 0

    First, assume that we have an infinite supply of mathematicians hitting random keys on a computer for a limited amount of time. Then we _know_ that they will almost surely find the proof:

    http://en.wikipedia.org/wiki/Infinite_monkey_theorem

  20. I think I read that wrong by Anonymous Coward · · Score: 0

    "Less space than is required to hold the entirety of Wikipedia"
    Wikipedia download, currently 9GB compressed and 44GB uncompressed.
    So technically correct, but completely useless for comparison? "this file so big -this other file is even bigger than it!"

  21. Re:Fags by mwvdlee · · Score: 1

    The only person dumber than a moderator that didn't understand that reference, is the person who comments on moderation after only 19 minutes.

    --
    Slashdot social media options: AIM, ICQ, Yahoo, Jabber and Mobile Text. Why no MySpace?
  22. Need a computer to check the proof by Megahard · · Score: 1

    And yes, it's computer proofs all the way down.

    --
    I eat only the real part of complex carbohydrates.
  23. Canadian Prime Minister would say... by jayveekay · · Score: 4, Funny

    "A proof is a proof. What kind of a proof? It's a proof. A proof is a proof. And when you have a good proof, it's because it's proven."

    Jean Chretien, former Prime Minister of Canada

    1. Re:Canadian Prime Minister would say... by weilawei · · Score: 1

      "A poof is a poof. What kind of a poof? It's a poof. A poof is a poof. And when you have a good poof, it's because it's poofin'." Jean B. Tokin, former Prime Minister of CanIHitThat

    2. Re:Canadian Prime Minister would say... by Anonymous Coward · · Score: 0

      A proof is a proof, you goof, you goof. And noone can check on a proof, you goof. Unless, you goof, that proof, you goof is the famous Erdos Discrepancy Conjecture for C=2.

      Wilbur Post

    3. Re:Canadian Prime Minister would say... by ClickOnThis · · Score: 1

      A proof is a proof, you goof, you goof. And noone can check on a proof, you goof. Unless, you goof, that proof, you goof is the famous Erdos Discrepancy Conjecture for C=2.

      Wilbur Post

      Ha! Nice retro-meme.

      --
      If it weren't for deadlines, nothing would be late.
    4. Re:Canadian Prime Minister would say... by sociocapitalist · · Score: 1

      "A proof is a proof. What kind of a proof? It's a proof. A proof is a proof. And when you have a good proof, it's because it's proven, eh."

      Jean Chretien, former Prime Minister of Canada

      FYFY

      --
      blindly antisocialist = antisocial
  24. Oh wait nevermind by LordLimecat · · Score: 1

    Turns out its just a memory dump from when a processor bug caused a kernel panic.

  25. Technological Singularity by peon_a-z,A-Z,0-9$_+! · · Score: 1

    The process, its results, and how its handled by humans will be an early example of decisions surrounding machine intelligence, in what will be the norm in the not-so-distant future.

  26. Oh, so that's what Beta is for by Tenebrousedge · · Score: 4, Funny

    Editor? This is Slashdot.

    You forgot to finish with the kick into the pit of death.

    But what if GP is already using Beta?

    --
    Those who advocate genocide deserve every protection afforded by law, and none afforded by common human decency.
  27. Ironic by Anonymous Coward · · Score: 0

    The bottom /. quote for me reads as follows -

    "Everything should be made as simple as possible, but not simpler." -- Albert Einstein

  28. Re:In response to the PM by steelfood · · Score: 2

    "Yes, I have smoked crack cocaine."

    Robert Ford, mayor of Toronto.

    --
    "If a nation expects to be ignorant and free in a state of civilization, it expects what never was and never will be."
  29. wait for theorem generating software by Anonymous Coward · · Score: 0

    I am looking forward for the moment, when computer will generate a nontrivial theorem 13GB long and prove it so that no human will be able to undertand the theorem, not even the proof.

  30. Proof? by Anonymous Coward · · Score: 0

    Human
    Math hypothesis
    Computer
    ??
    ??
    ??
    ??
    Proof!
    ?
    ?
    ?
    Profit!!!!

  31. It's ONLY 6.5M pages! by Anonymous Coward · · Score: 0

    Let's see. If I can read a 500 page book in a day, it would ONLY take me 35.6 years to read the proof! And that says nothing about proving/disproving/understanding it! :rolleyes:

    1. Re:It's ONLY 6.5M pages! by maxwell+demon · · Score: 1

      So how long will it take to check if you give it to 1000 people and let each one check 6500 pages?

      --
      The Tao of math: The numbers you can count are not the real numbers.
  32. Crowdsource the proof checking! by Anonymous Coward · · Score: 0

    Many eyes make a shallow proof. Just have everyone check one step, and the whole proof will be checked in no time.

  33. My Only Questions by canadiannomad · · Score: 1

    My only questions are is it possible to simplify the proof? And how hard would that be?
    If we have a testable proof, then it should be possible to throw another algorithm on it to simplify and optimize it...
    Only after that step should it be considered ready to inspect and test by others.

    --
    Hmm, the humour and sarcasm seem to have been be lost on you.
    1. Re:My Only Questions by maxwell+demon · · Score: 1

      But if there turns out to be an error in the simplified proof, how do you know whether it's an error in the original proof, or an error of the simplification?

      --
      The Tao of math: The numbers you can count are not the real numbers.
  34. Gonna check it out by Anonymous Coward · · Score: 0

    Be right back.

  35. SAT is not a brute force loop by Mask · · Score: 5, Informative
    As someone nearing the completion of his Ph.D. in a subject close to SAT I can say that SAT does not resemble "one big for loop", not a bit. A modern SAT solver can solve problems with millions of variables and hundreds of thousand clauses. In contrast, a brute force for loop would require O(2^N) iterations where N is in the millions, which is like eternity. As an exercise, please try to write a trivial solver that can handle even 100 variables.

    Also, unlike what you may think, a SAT proof is not a list of "I tried a=1 and it did not work out, and this is the proof that a=0". A standard SAT proof deduces new clauses from the original problem by applying the resolution rule repeatedly. The newly deduced clauses reduce the search space and, if the problem is unsatisfiable, the solver ends up with the empty clause, which is always FALSE. The proof is a collection of resolution steps that lead to FALSE.

    SAT solvers are AI at least since:
    • 1. They employ search (not unlike chess game).
    • 2. They have non-trivial heuristics (not unlike chess game).
    • 3. The heuristics evolve and improve over the course of a run.
    • 4. They are able to deduce new clauses from the original problem.
    • 5. Many solvers employ a lot of smarts to simplify the problem even before starting search.

    SAT is clearly NP complete, and clearly the existence of good SAT solvers is not a proof that P=NP. This means that there will be relatively small problems that SAT solvers won't be able to solve. On the other hand, most real-world problems have a hidden structure which SAT solvers are able to find and use to their advantage.

    1. Re:SAT is not a brute force loop by Anonymous Coward · · Score: 0

      Your comment was interesting, for sure, but it still seems like you might be squabbling over the definition of "brute force". Clearly the solver is looping over some code... You could do the same thing by hand, but the advantage of the computer is that it can keep doing it over and over again, and quickly.

    2. Re:SAT is not a brute force loop by Kufat · · Score: 5, Interesting

      Yeah, I'm familiar with SAT solvers and the fact that they aren't REALLY full brute force; I oversimplified it a bit for the Slashdot crowd. Might have gone a little too far on the "lies to children" scale, mea culpa.

      My point was that anyone with high school level math experience can understand the basic problem of boolean satisfiability; I was trying to draw a distinction between problems that are beyond human comprehension and those that are merely beyond human time and ability, with huge SAT instances falling into the latter category. Shouldn't have glossed over the details quite as badly as I did.

    3. Re:SAT is not a brute force loop by Mask · · Score: 2

      You are right that the basic concepts of SAT solving can be understood by a smart person with high school math experience. But I don't agree that this is as simple as that for the fine details of modern SAT solvers. Some solving steps are non-trivial and look weird some times. Especially the steps that the solver takes to simplify the problem, in the middle of the run.

      Today, SAT is not only about binary resolution. Some of the stuff is difficult even for Grad students. There are hundreds of non-trivial papers describing proven and effective algorithms, and thousands more with a good potential. I know only a small fraction of this as this is not my main field of research, but occasionally I read a research paper on SAT when it catches my eye.

    4. Re:SAT is not a brute force loop by Yaztromo · · Score: 3, Interesting

      SAT is clearly NP complete, and clearly the existence of good SAT solvers is not a proof that P=NP. This means that there will be relatively small problems that SAT solvers won't be able to solve.

      Enjoyed your post, but have to correct a small quibble.

      From a mathematical standpoint at least, being NP complete doesn't imply that there are some problems that are unsolvable; merely that they won't be solvable in any reasonable amount of computing time. If you have a few hundred billion years of compute time available, a SAT solver might be able to solve even those small problems you mention. Of course, from a practical perspective, none of us are going to be here to get the result in those situations, making them unsolvable from a practical standpoint.

      (On the other hand, once the billions of aeons roll by and the machine goes 'ding' and spits out an answer, we do know that we can verify it in poly time. Huzzah!)

      While all of this may seem ultra-pedantic, there is enough confusion about NP out there that someone reading your post may get the idea that things that are NP-complete are unsolvable. They're not unsolvable -- we can typically fashion algorithms to solve them, simply that those algorithms run in nondeterministic polynomial time, and thus may have runtimes exceeding the expected lifetime of the solar system, even with every cycle of compute time ever invented pushed at it.

      ...unless, of course, someone comes up with a proof that P = NP, in which case all those NP-complete problems can be transformed into P problems. Sure, they might still take a few hundred billion years to get a solution, but at least we'd know how many hundreds of billions of years would be needed to get a solution!

      Yaz

    5. Re:SAT is not a brute force loop by ckatko · · Score: 1

      >A standard SAT proof [wikipedia.org] deduces new clauses from the original problem by applying the resolution rule [wikipedia.org] repeatedly.

      Can we put those in a for loop?

    6. Re:SAT is not a brute force loop by Anonymous Coward · · Score: 0

      No. Just no.

      SAT solvers have nothing to do with Artificial Intelligence or even Computational Intelligence. If you want to classify SAT solvers, they fit into optimization.

      *Definitely* not AI.

      Now, if you are seeking to affirm "SAT solvers can be applied to AI problems", then the answers would be yes.

    7. Re:SAT is not a brute force loop by Anonymous Coward · · Score: 0

      On the other hand, most real-world problems have a hidden structure which SAT solvers are able to find and use to their advantage.

      It might be worth mentioning that a whole class of real-world circuits do not have this hidden structure, and SAT solvers cannot solve them quickly:

      1. Binary multiplication. A fast SAT solver could factorize numbers very quickly, attacking RSA.
      2. SHA-256. A fast SAT solver could perform reverse-hashing, attacking BTC.
      3. General bit-twiddling blocks used in encryption e.g. AES

      Unfortunately there is enough intermixing at every level of these circuits that there is no substructure to extract.

  36. SAT solving is NP-complete by Anonymous Coward · · Score: 0

    As a result all SAT solver implementations are heuristic approximations of a true SAT solver.

    How do they account for this in the paper?

    1. Re:SAT solving is NP-complete by tajribah · · Score: 1

      SAT solvers usually guarantee that their result is correct. What they don't guarantee is that they finish in reasonable time for every input.

  37. At least that dammed Beta is not popping up! by Anonymous Coward · · Score: 0

    At least that dammed Beta is not popping up!At least that dammed Beta is not popping up!

    Back to a nice user friendly Slashdot.

  38. Back To School by JohnPerkins · · Score: 1

    Dammit. I have a Bacon number (2). Now I have to go get my PhD and try to get an Erdos number. I can't beat the current lowest Erdos-Bacon number (4, held by Steven Strogatz), but I could tie it. Unless...If I can get onto a movie with Bacon himself in it, that might put 3 in striking range.

  39. A Mathematical Proof Too Long To Check by Publiu5 · · Score: 1

    Where is "The Nth Degree" Barclay when you need him!AA

  40. SOP in Congress by SmartCookie · · Score: 1

    No problem -- just give it to Nancy Pelosi. She'll make sure it gets passed; and then you can find out what's in it. Congress doesn't read the bills is passes, why should mathematicians think they are so much better? ;^J

  41. mechanical turk! by Anonymous Coward · · Score: 0

    Amazon's mechanical turk to the rescue!

  42. Where would we be without African geniuses? by Anonymous Coward · · Score: 0

    I take it this proof was produced by AFRICANS, since 'they are just as intelligent as other races', and 'We are all the same'?

    What's that you say? There aren't any African maths geniuses? How can that possibly be? The TV told me we are all the same!

  43. F U C K . B E T A by Anonymous Coward · · Score: 0

    Fuck Slashdot and fuck the Beta. I hope people at DICE have a terrible cancer-induced deaths, along with all their families.

  44. It's just a proof strategy... by jopsen · · Score: 1

    I was trying to draw a distinction between problems that are beyond human comprehension and those that are merely beyond human time and ability, with huge SAT instances falling into the latter category.

    Exactly, the use of SAT unsatisfiability certificates is just a proof strategy... Just like reductions used to show complexity classes, nobody comprehends all of them...

  45. I don't understand...? by cyn1c77 · · Score: 1

    ...why can't they just get their slaves, I mean graduate students, to check its validity by hand?

  46. Please tell me I'm dreaming! by wdhowellsr · · Score: 1

    Please tell me the browser cache is screwing with me. Please tell me that my wife wants to have sex more often ( ok that isn't going to happen, I have a 12 and 15 year old) Do we really have Slashdot.org back?

  47. Simple to check by tpstigers · · Score: 1

    Just give the file to Spock. Or Thufir Hawat.

  48. Not the first such proof, by a long shot by Len · · Score: 1

    There are other theorems with computer-assisted proofs that are too complex to verify by hand, going back decades. The four colour map theorem and the classification of finite simple groups are two examples.

  49. Too long to peer review by Anonymous Coward · · Score: 1

    Too long for peer review; Claim Rejected.

  50. Q.E.D. by Anonymous Coward · · Score: 0

    Why not use the rigorous method used to prove the existence of global warming:
    Just state that it's true and that anyone who disagrees is an idiot.

  51. Hummers by Anonymous Coward · · Score: 0

    That's how I measure girls

  52. How About Pi? by Scarletdown · · Score: 1

    Okay, so the proof in the article may be too lengthy to accurately check, so why not work with something simpler.

    For that, I present the proof that Pi R Square is incorrect.

    1: Write down on a piece of paper the commonly used 3 digit shortened approximation of Pi: 3.14
    2: Hold that paper up in front of a mirror.
    3: Note that in reverse, the characters 3.14 now look like PIE.
    4: Pie is typically round, therefore since Pie is round, PI.E is 3.14 backwards, and 3.14 is the common shortened value of Pi, then Pi R round, not square.

    --
    This space unintentionally left blank.
  53. I have discovered a truly marvelous proof ... by littlewink · · Score: 1

    of this which is shorter. Unfortunately this comment field is too small to contain it.

  54. Beta sucks by Anonymous Coward · · Score: 0

    My comments won't even post. Fuck beta.

  55. Errors? by Anonymous Coward · · Score: 0

    There was an error in page 3.

  56. I realised this when doing my PhD in 2002. by John+Allsup · · Score: 1

    I was trying to classify the normal subgroups of PSL(n,q) where n,q may be nonstandard elements of a nonstandard model of arithmetic. I pointed out that if Ariah Lev's work formalised correctly, then a few steps would yield the result I wanted, but that this was beyond checking. Once the PhD was done, I did further investigation, and scribbled a thought in a moment of insight, and left it to tidy itself up. I believe I put an entry on either chalisque.wordpress.com or deardiary.chalisque.org, but forget which, and am hunting it down. If not, John's Antibang Theory That Really Works and its notion of True Computability vs Turing equivalent non-True forms will see the light of day in a readable format, but if you want to know how my mind really thinks, this is a clue as to my mind's native language. It's quasi-English pseudo-maths that I then filter for correctness before communicating.

    I can't find it, but there are a great many thoughts I had to dump out to reclaim brainspace. As a free software believer, and a free-thinking believer, I treat my programs and thoughts like a mother treats her children, caringly and lovingly and I don't send them out into the world ill-equipped to face rigorous challenge.

    --
    John_Chalisque
  57. Dear mathematician... by Anonymous Coward · · Score: 0

    Where's my anti-gravity! Movies promised me anti-gravity and fusion. I know you're almost there on the fusion thing but I want my darned pink hoverboard. I think the lack of hoverboards causes all the problems of the world today. Who could question you if you were hovering over their heads with a rod that shot electricity?

    P.S. I know you're not a physicist and the lack of this stuff isn't really your fault but all this stuff starts with the pure math so....I'm blaming you

  58. Me i go with furlongs by Anonymous Coward · · Score: 0

    Furlongs are the standard arbitrary unit of distance. Or maybe parsecs. Or chains.

  59. But by bananahead · · Score: 1

    But is he is or is he isn't correct?

    --
    A most overlooked advantage to owning a computer is if they foul up there's no law against wacking them around a bit.
  60. Can't we all just get along? by bananahead · · Score: 1

    Or we can all just agree that it's probably right and move on to something else.

    --
    A most overlooked advantage to owning a computer is if they foul up there's no law against wacking them around a bit.
  61. Already done with Four Color Theorem by Anonymous Coward · · Score: 0

    I don't know if anybody will read this far down, but the topic has already been "done" with the Four Color Problem, in which a mechanical proof, too long for a human to review in a lifetime of work, was necessary to show that "four colors suffice".

  62. Having another program check is not sufficient by YoungManKlaus · · Score: 1

    because papers have shown that most programming problems occur in the same part of the program (either because of requirements understanding or common misconceptions).