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Are Computers Ready to Create Mathematical Proofs?

DoraLives writes "Interesting article in the New York Times regarding the quandary mathematicians are now finding themselves in. In a lovely irony reminiscent of the torture, in days of yore, that students were put through when it came to using, or not using, newfangled calculators in class, the Big Guys are now wrestling with a very similar issue regarding computers: 'Can we trust the darned things?' 'Can we know what we know?' Fascinating stuff."

94 of 441 comments (clear)

  1. Rumsfeld, anyone? by dolo666 · · Score: 5, Funny

    > 'Can we know what we know?' Fascinating stuff.

    Reminds me of Rumsfeld... "Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."

    1. Re:Rumsfeld, anyone? by kfg · · Score: 2, Funny

      Are you sure?

      KFG

    2. Re:Rumsfeld, anyone? by Tower · · Score: 5, Informative

      Actually, this is three of the four quadrants of knowledge...

      KK | KD
      ___|____
      |
      DK | DD

      So, you can:
      Know that you Know something
      Know that you Don't Know something (the second most common)
      Don't Know that you Don't Know something (most things fall in this category for most people)
      Don't Know that you Know something (the most interesting of the categories)

      Big, huge, red tape operations can easily fall into the latter category (DK)... since it is rather easy for a group to obtain knowledge, yet be unaware of it [political commentary omitted].

      --
      "It's tough to be bilingual when you get hit in the head."
    3. Re:Rumsfeld, anyone? by Deraj+DeZine · · Score: 4, Funny

      Well, I had been in the don't care that I don't know category; now I'm in the don't care that I know. Great.

      --
      True story.
    4. Re:Rumsfeld, anyone? by cs · · Score: 5, Interesting

      Can't remember where I came across this, but for entertainment:

      Men are four:
      He who knows and knows that he knows; he is wise, follow him.
      He who knows and knows not that he knows; he is asleep, wake him.
      He who knows not and knows that he knows not; he is ignorant, teach him.
      He who knows not and knows not that he knows not; he is a fool, spurn him!

      I'm sure it's coloured my attitude to supporting users:-)

      --
      Cameron Simpson, DoD#743 cs@cskk.id.au http://www.cskk.ezoshosting.com/cs/
    5. Re:Rumsfeld, anyone? by jgabby · · Score: 5, Funny

      Then there's:

      My boss, who knows that he knows not;
      But pretends that he knows that he knows;
      And he's so convincing at it, that;
      People who know that he doesn't know;
      Beleive that he knows that he knows anyway.

    6. Re:Rumsfeld, anyone? by sbaker · · Score: 4, Interesting

      I'm not sure that there are only those four catagories.

      Godels theorem pretty much says that there are things that you can NEVER know are true or false...and that in some cases you can PROVE that you can never know them.

      This leads to some other states that your knowledge can be in:

      CERTAINTY OF UNCERTAINTY: In some cases you can know (by solid mathematical proof) that you can never know some particular thing. For example. we know with absolute certainty - that you can't solve the 'Halting Problem' (to prove whether an arbitary computer program will eventually halt or whether it'll run forever). That's something we KNOW we'll never be able to do no matter how smart we get. That's not the same as KK/KD/DK or DD. It's tempting to lump this in with KD - but in the case of simply being aware that we are ignorant of something, we might take steps to resolve that ignorance. In this case, we know that this is something we cannot EVER know.

      CERTAINTY OF POTENTIAL CERTAINTY: If you know the current "largest prime number" - then by definition, you don't know of a larger prime - but you DO know that you could definitely find a larger prime if you really wanted to.

      UNCERTAINTY OF POTENTIAL CERTAINTY: Then there are other things that you might not know whether they are knowable or not - such as the proof of some of the classic mathematical problems. Before Fermat's last theorem was proved, nobody was sure whether it could be proved or not.

      --
      www.sjbaker.org
    7. Re:Rumsfeld, anyone? by benna · · Score: 2, Insightful

      There was a young man who said, "though
      it seems that I know that I know,
      what I would like to see
      is the I that sees me,
      when I know that I know that I know."

      Great poem, Alan Watts used to quote it alot when talking about the illusion of the ego.

      --
      "It is not how things are in the world that is mystical, but that it exists." -Ludwig Wittgenstein
  2. Can someone elaborate on... by Anonymous Coward · · Score: 2, Interesting

    ...precisely why it's so hard to see that a pyramid of cannonballs is an optimal stack? This seems almost axiomatic.

    I guess the obvious Monte Carlo simulation doesn't constitute "proof," but still, what exactly is the big question here?

    1. Re:Can someone elaborate on... by stephentyrone · · Score: 5, Informative

      It's not hard to *see*. It's hard to *prove*. Very little of mathematics is consumed with proving deep, mystical statements that no one would ever anticipate to be true. Much (maybe most) of mathematics is built around proving (relatively) obvious things. Why bother? because sometimes, relatively obvious things turn out to be false, and there's no way to know that they won't until you've prooved them true. In general, showing that discrete (or semi-discrete) phenomena are optimal is fairly tricky; you can't just appeal to calculus to optimize some function. You often have to somehow break the search space up into a bunch of disjunct cases that span all the possibilities, and be able to prove that they span all possibilities. Then, if you're lucky, you can use some kind of calculus-type argument on the continuous spaces you're left with.

    2. Re:Can someone elaborate on... by baywulf · · Score: 2, Insightful

      Sometimes a precise mathematical analysis can lead to startling insights. Perhaps there are multiple solutions equally optimal. Perhaps it gives a general algorithm that works for other shapes.

    3. Re:Can someone elaborate on... by uncleO · · Score: 3, Informative

      What if the stack is very large, for instance? Is it still obvious that the pyramid is best? Consider a similar problem, that of packing squares in a rectangle. When the rectangle is small, it is obvious that the best way is to pack them together starting from one corner, leaving a little wastage on the opposite two sides. It seems strange, but it is true, that when the recangle is very large, this strategy is not optimal. More squares can be packed when they are not packed in such a regular pattern. This is the main difficulty with proofs of this type. It can be easy to prove that a given strategy is not optimal, but not so simple to show that no better strategy can exist.

    4. Re:Can someone elaborate on... by JoranE · · Score: 2, Interesting

      Definition of optimal: At least as good as EVERY other possible configuration of (in this case infinitely many) oranges in 3-space.

      If by "see" you mean "conjecture" then, yes, it is easy to see. If by "see" you mean "prove", and thereby catch a glimpse into the fundemental reasons WHY this is the best possible stacking, then it is exceedingly difficult.

      How would you go about designing a proof that would take into account every single one of the infinitely many configurations of oranges? Could you even list them? Indeed, I read somewhere that Hales said that the hardest part was reducing all the infinitely many configurations into something like 5,000 cases.

      Focus on the infinite part of this problem: we're looking for an arrangement of infinitely many oranges in space such that we maximize the density of the oranges. Now, is it obvious to you that an (infinite) pyramid is denser than packing them somehow into a sphere-ish shape (with infinite radius of course)? It certainly isn't to me...

      I'm not sure is this is very convincing, but it's the best I can do without really researching the problem.

    5. Re:Can someone elaborate on... by adamruck · · Score: 2, Insightful

      um.... your wrong about that... and alot of people dont understand this either.

      all of our knowledge is based upon assumptions. For instance when it comes to the number systems... we have a set of assumtions that we say are true.. and there is no arguing about it. For instance in the binary system. We say the language only consists of 0 and 1. We say there are two operators and define there operations. AND/OR... we say 0 and 0 is 0.... we say 1 and 1 is one. There is NO PROOFING THIS... its a given. We can PROOF things like demorgans therom.

      This applies to many many areas... geometry... algebra.. calc... logic... etc. There are a list of assumptions that are given to be true. You could argue that calc is just an extention of algebra and geometry... but thats another matter.

      The question I think this article is asking ... is can we program this truths into a computer... give a program a problem... have it randomly(or not for the ai people) apply some theory.. and get an actual answer?

      In my own personal opinion, I think this would work. I think if you took it far enough.. giving information about math... chemistry and physics and electronics.... I think it would be possible to have a computer design a better computer.

      --
      Selling software wont make you money, selling a service will.
    6. Re:Can someone elaborate on... by CommieOverlord · · Score: 3, Insightful
      Because if you do that you've failed to do two things:
      1. Failed to demonstrate that the observed phenomenon is consistent across all possible sets (up to infinite size) of oranges, instead of the one set you have.
      2. Failed to demonstrate that the oberved phenomenon is consistent across every possible method of stacking.

        What you've done is shown that for a subset of the sets of oranges and a subset of the sets of stacks the pyramid is better.

        A mathematical proof shows something is true for every single element of the sets.
  3. Create vs. Verify by Squeamish+Ossifrage · · Score: 5, Informative

    The headline does a slight disservice in describing the article that way: Whether or not computers can create proofs isn't an issue. The problem comes when the resulting proof is too involved to be verified by a human, and so the computer's work has to be trusted.

    1. Re:Create vs. Verify by Vancorps · · Score: 4, Insightful
      If humans created the computer to do the task should they not trust that it would do the task and do it well? Perhaps, perhaps not.

      A computer could quite easier come up with a very complex answer simply because it can do more calculations in a given second than a human can. Of course humans take in a lot more variables at a given time so the numbers are actually very opposite but I'm sure you get my point.

      I think you test it with progressively more different problems, if the answers come out precise and accurate then you can build your level of trust in the system. Kind of like the process of getting users to trust saving to the server after a bad crash wiped everything because the previous admin was a moron.
    2. Re:Create vs. Verify by Xilo · · Score: 4, Insightful

      involved, not complicated - like the Four Color [Conjecture]. Noone could figure out a way to actually prove it, so some one (or group of someones) wrote a program to systematically determine all the possible arrangements of regions in a simplified series of maps, and then figure out how to color each of those maps. The involved part was .. well, all of it. It wasn't necessarily very complicated, just labor-intensive. Computers are perfectly suited for tedium.

      --
      Read; Write; Execute
    3. Re:Create vs. Verify by Llywelyn · · Score: 4, Insightful

      Sometimes it is enough to know that something is *true* or *false* without having to know the details of the in-between steps.

      I'll give some trivial examples to illustrate:

      For a famous example, it would provide a great deal of peace of mind if we could prove that P != NP. It wouldn't matter that we understand that proof so much as that it is *provably true*. If, on the other hand, it is proven false that is just as important (if not more so) and while an understanding of the proof might lead more easily to examples of such, we would know (for certain) that trusting public key encryption over the long run would be a Bad Idea(TM) (for example) and that it is just a matter of time before a polynomial time algorithm is developed.

      (Not that such will necessarily be fast, mind you, but we would know it would exist).

      For another example--there are certain things that can be inferred if Poincare Conjecture is true for N=3. If we can prove the Poincare Conjecture is true (and it is now thought that it might be) it means things to physicists, even if we don't know why it is true.

      The bigger question here is "can we trust it if we can't verify it by hand."

      --
      Integrate Keynote and LaTeX
    4. Re:Create vs. Verify by cgenman · · Score: 3, Insightful

      Don't we already have tons of resources devoted to verifying the accuracy of a computing environment? If we verify the logic and accuracy of the computer, much like the axioms of mathematics, cannot we then say that the resulting proof must be valid?

      Of course, if it can't be understood by humans, it doesn't really help anything, as one of the main points of proving things is to gain insight into how to prove other things. But wouldn't building the system to proove proofs be itself a different but valuable tool?

    5. Re:Create vs. Verify by panaceaa · · Score: 5, Funny

      Fortunately for you software researchers haven't programmed computers to create their own long sentences with so many prepositions that human readers of the created sentences are unable to remember the subject or figure out which verb, or possibly adjective, the trailing adverb applies to by the time they have read the entire sentence yet!

    6. Re:Create vs. Verify by eightheadsofdoom · · Score: 5, Insightful

      That's exactly the case. I had Ken Appel as a professor, and he mentioned the 4-color theorem a couple of times. As he put it, the math wasn't intensive, but actually doing the work the computer was able to do would have taken an army of grad. students years to finish. The way he saw it, the proof was understandable, just extraordinarily, arduously long. That's when they decided to use a computer to solve the problem. Unfortunately, there are still many pure mathematicians who shun computer-based proofs because they (or their grad. students) are not working things out with their own pencils. Unfortunately, I don't think that's a problem that's going away, but I do think it opens up some interesting doors such as writing program A to prove a theorem, and then haveing to prove program A's correctness, for which you write program B and so forth.

    7. Re:Create vs. Verify by sisco · · Score: 2, Funny

      "For a famous example, it would provide a great deal of peace of mind if we could prove that P != NP."

      Well, P == NP for N = 1.

      That's the beauty of a counter example.

      --
      DATA comments; PROC SORT DATA = comments BY score; PROC DELETE comments >> 1; RUN; DATA entertainment SET commen
    8. Re:Create vs. Verify by eliza_effect · · Score: 5, Funny

      Can you please tell us The Question?

      The Ultimate Question?

      Yes!

      Of Life, The Universe..

      And everything?

      And Everything.

      Yes.

      Tricky..

      But can you do it?

      ...No. But I'll tell you who can.

      Who? Tell us!

      I speak of none, but the computer that is to come after me.

      What computer?

      A computer whose merest operational parameters I am not worthy to calculate and yet I will design it for you. A computer which can calculate The Question to the Ultimate Answer. A computer of such infinite and subtle complexity that organic life itself will form part of it's operational matrix. And it will be called.. The Earth.

      What a dull name.

    9. Re:Create vs. Verify by njj · · Score: 4, Interesting

      If we can prove the Poincare Conjecture is true
      OK, yes, that would definitely be worth doing. Various chunks of 3-dimensional geometric topology currently include the caveat ``... if the 3-dimensional Poincare Conjecture is true.''

      (and it is now thought that it might be)
      Depends who you talk to, of course. Perelman reckons he's got an outline proof of Thurston's Geometrisation Conjecture, which implies the Poincare Conjecture as a corollary. But as I understand it he's not actually proved it, just described how one would go about proving it - essentially saying ``It's over the other side of that hill''. Now Perelman is a very bright lad (cleverer than I am) but the Poincare Conjecture has a long history of almost being proved (my research supervisor (I've just finished a PhD in algebraic and geometric topology) almost did it about twenty years ago, for example, but there was a very subtle and unresolvable flaw in his argument) so I'm going to reserve judgement until the paper turns up in the Annals of Mathematics.

      I wouldn't be surprised if the Conjecture turned out to be true, as the corresponding result is known to be true in dimensions 1,2,4,5,... (well, to be picky, the smooth 4-dimensional case hasn't been proved yet, but the topological and piecewise-linear ones have). But equally, I wouldn't be shocked if it weren't - 3-dimensional topology is a weird subject, as there's enough room to start discussing interesting things, but there's not so much room that everything trivialises.

      Quick precis of the Conjecture:
      ``If it looks like a sphere, it is''.

      Slightly less quick precis of the Conjecture:
      Given any topological space X, we can assign a sequence of groups (`homotopy groups') pi_n(X) to it, so that pi_n(X) in some sense describes the n-dimensional structure of X. An n-manifold (a topological space which locally `looks like' ordinary, flat n-dimensional space) which has the same sequence of homotopy groups as the 3-dimensional sphere, is called a `homotopy 3-sphere'. The Poincare Conjecture is that the 3-sphere itself is the only homotopy 3-sphere.

      So, to prove it, we have to show that every homotopy 3-sphere is topologically equivalent (`homeomorphic') to the 3-sphere. And to disprove it, we just have to find one counterexample - a homotopy 3-sphere which isn't equivalent to the 3-sphere itself.

      Now to use a computer to prove the Conjecture, we need to find some way of verifying that every possible homotopy 3-sphere is equivalent to the 3-sphere. This is theoretically doable - there's an algorithm (the Rego-Rourke algorithm) which lists (with redundancy), all possible homotopy 3-spheres. There's another algorithm (the Rubenstein-Thompson algorithm) which, given a homotopy 3-sphere, can tell if it is equivalent to the 3-sphere. So in theory we just feed the output of the RRA into the RTA.

      Except that there are an infinite number of possible homotopy 3-spheres to check, so if the Conjecture is true, this program will never terminate.

      Now if you can find some way of reducing the cases under consideration to some finite subset (by, for example, showing that all but a finite number of homotopy 3-spheres obviously satisfy the conjecture) then using a computer suddenly becomes a worthwhile endeavour. This is basically what Appel and Haken did with the Four-Colour Map Theorem.

      The computer approach is also useful for searching for counterexamples, and for verifying that all cases up to some level of complexity satisfy the Conjecture.

      But where computers aren't currently going to help, is in the actual creative side of things - a lot of important modern mathematics (and the related theorems and proofs) has come from very clever humans saying ``OK, what happens if we try this (utterly weird and counterintuitive) thing here'' and having the aesthetic sense to tell when something's actually interesting or just irrelevant. Until computers are capable of this kind of creative/intuitive/aesthetic/etc behaviour, I doubt they're going to be replacing human research mathematicians any time soon.

      nicholas

  4. 'Can we trust the darned things?' by FFFish · · Score: 4, Funny

    Depends whether it's a Pentium with an FDIV bug, I imagine...

    --

    --
    Don't like it? Respond with words, not karma.
    1. Re:'Can we trust the darned things?' by Anonymous Coward · · Score: 2, Insightful

      You know what? I work for Intel. My company paid 1/2 billion dollars replacing Pentium chips with that bug that nobody would ever notice except maybe six people. Software vendors get away with murder. They don't even have to replace their product even if it is not fit for it's stated purpose. The FDIV bug was a typo in some kind of table. Doesn't that make it software in a way? One little bug years ago and still people laugh about it (SCORE:4, Funny).

  5. Will this complicate what we can understand? by Anonymous Coward · · Score: 3, Interesting

    I think the issue will become: can we learn anything on our own, we don't want to rely on imposibly long proofs. My calc teacher hates us using calculators, she thinks it will be the end of calculus as we know it.

    1. Re:Will this complicate what we can understand? by djplurvert · · Score: 2, Insightful

      If you are still trying to learn how to add in calculus class then there are bigger problems.

      It is one thing to deride the use of cacluators because they are crutches, it is another thing altogether to deride them because you are a technophobe.

      Technology is extremely useful in aiding understanding and exploration of mathematics. If you eliminate calculators and computers in schools, even high schools, you may hurt the chances of your students to succeed in an increasingly technical world.

      As usual, I think the correct response is a balanced response. Demonstrate how to use technology as a tool and provide assessment that requires demonstration of ability without the use of a calculator as a crutch.

      In a calculus class, for example, divide the exams into two parts, or alternate between calculator allowed, and calculator disallowed exams.

      Of course, this has little to nothing to do with the nytimes article but it always seems to come up in these discussions.

      plurvert

    2. Re:Will this complicate what we can understand? by azaris · · Score: 2, Insightful

      Simple. The student should know the value of pi to a certain number of significant figures.

      Why? Einstein was once asked how many digits of Pi he could remember. He replied "maybe three or four". The interviewer then exclaimed: "But Sir, some people have memorized hundreds of digits!" Einstein's reply was: "Ah, but I know where to look them up if I need them."

      With a calculator, they're just typing in 3*pi and getting an answer with 8+ significant digits. Without a calculator, they're actually calculating the answer as close as they can based on how many significant digits they know.

      Wrong, wrong, wrong. If the answer to some problem is 9 Pi then the answer to that problem is 9 Pi, not 28.274333882308139146163790449516.

      That's a better test of who's mastering mathematics.

      Memorizing Pi and doing multiplication on paper has almost no relevance at all to "mastering mathematics".

  6. I think so, yes. by James+A.+M.+Joyce · · Score: 3, Informative

    I mean, we've used computers to prove much of boolean and linear algebra. The most famed result in the field is that of the Robbins Conjecture, proven entirely by computer. The computer produced a very "inhuman" proof...

    1. Re:I think so, yes. by Quill345 · · Score: 5, Insightful

      Automated theorem provers have been around for a long time, if you can express your thoughts using first order logic. Here's a program from 1986... lisp code

  7. It was a big help with the 4-color map proof... by The+Beezer · · Score: 5, Informative

    and there are already programs out that help with this. Here's one for example...

  8. Re:I don't care by Vancorps · · Score: 3, Interesting
    That can actually be a good point, when you make a task faster and easier then you can sacrifice a little accuracy here and there.

    When the results become too inaccurate then you have to change your tools, so unless accuracy is key, such as NASA's calculations and the likes then you work on making a computer do as much as possible to eliminate human error and humans can be there to adjust the almost mythic fudge factor

  9. Text of the article by Anonymous Coward · · Score: 2, Informative


    In Math, Computers Don't Lie. Or Do They?
    By KENNETH CHANG

    Published: April 6, 2004

    leading mathematics journal has finally accepted that one of the longest-standing problems in the field -- the most efficient way to pack oranges -- has been conclusively solved.

    That is, if you believe a computer.

    The answer is what experts -- and grocers -- have long suspected: stacked as a pyramid. That allows each layer of oranges to sit lower, in the hollows of the layer below, and take up less space than if the oranges sat directly on top of each other.

    While that appeared to be the correct answer, no one offered a convincing mathematical proof until 1998 -- and even then people were not entirely convinced.

    For six years, mathematicians have pored over hundreds of pages of a paper by Dr. Thomas C. Hales, a professor of mathematics at the University of Pittsburgh.

    But Dr. Hales's proof of the problem, known as the Kepler Conjecture, hinges on a complex series of computer calculations, too many and too tedious for mathematicians reviewing his paper to check by hand.

    Believing it thus, at some level, requires faith that the computer performed the calculations flawlessly, without any programming bugs. For a field that trades in dispassionate logic and supposedly unambiguous truths and falsehoods, that is an uncomfortably gray in-between.

    Because of the ambiguities, the journal, the prestigious Annals of Mathematics, has decided to publish only the theoretical parts of the proof, which have been checked in the traditional manner. A more specialized journal, Discrete and Computational Geometry, will publish the computer sections.

    The decision represents a compromise between wholehearted acceptance and rejection of the computer techniques that are becoming more common in mathematics.

    The debate over computer-assisted proofs is the high-end version of arguments over using calculators in math classes -- whether technology spurs greater achievements by speeding rote calculations or deprives people of fundamentals.

    "I don't like them, because you sort of don't feel you understand what's going on," said Dr. John H. Conway, a math professor at Princeton. But other mathematicians see a major boon: just as the computers of today can beat the grand masters of chess, the computers of tomorrow may be able to discover proofs that have eluded the grandest of mathematicians.

    The packing problem dates at least to the 1590's, when Sir Walter Raleigh, stocking his ship for an expedition, wondered if there was a quick way to calculate the number of cannonballs in a stack based on its height. His assistant, Thomas Harriot, came up with the requested equation.

    Years later, Harriot mentioned the problem to Johannes Kepler, the astronomer who had deduced the movement of planets. Kepler concluded that the pyramid was most efficient. (An alternative arrangement, with each layer of spheres laid out in a honeycomb pattern, is equally efficient, but not better.) But Kepler offered no proof.

    A rigorous proof, a notion first set forth by Euclid around 300 B.C., is a progression of logic, starting from assumptions and arriving at a conclusion. If the chain is correct, the proof is true. If not, it is wrong.

    But a proof is sometimes a fuzzy concept, subject to whim and personality. Almost no published proof contains every step; there are just too many.

    The Kepler Conjecture is also not the first proof to rely on computers. In 1976, Dr. Wolfgang Haken and Dr. Kenneth Appel of the University of Illinois used computer calculations in a proof of the four-color theorem, which states that any map needs only four colors to ensure that no adjacent regions are the same color.

    The work was published -- and mathematicians began finding mistakes in it. In each case, Dr. Haken and Dr. Appel quickly fixed the error. But, "To many mathematicians, this left a very bad taste," said Dr. Robert D. MacPherson, an Annals editor.,

    To a

  10. I see no good reason why not.... by kommakazi · · Score: 4, Interesting

    Computers are a human creation...it's not a matter of whether we can trust the computer, but rather a matter of can we trust that the people who built the computer and coded the software it runs knew what they were doing and didn't make any errors. Computers can only do what we tell them to...so really it was humans who indirectly made the proofs by producing a system capable of doing so. All it really boils down to is whether the folks who made the system and it's software knew what they were doing or not and whether they made any errors or not.

    1. Re:I see no good reason why not.... by Rosyna · · Score: 2, Insightful

      See the problem is humans can only program a computer to do something the human coding it knows how to thoroughly describe. It is also why you won't see a computer naturally speaking, showing emotions, or doing anything else we cannot describe today.

      It is amusing to see computers being used as proof bringers when you usually need a proof to program the darn things.

  11. no by sporty · · Score: 2, Funny

    no.

    q.e.d.

    --

    -
    ping -f 255.255.255.255 # if only

  12. Theorem Provers by bsd4me · · Score: 4, Informative

    Theorem provers have been around for a long time. A net search should turn up a ton of hits. The key is to implement a system that can be verified by hand, and then build on it.

    --

    (S(SKK)(SKK))(S(SKK)(SKK))

  13. new facet of an old issue by colmore · · Score: 5, Insightful

    20th century mathematics has seen some pretty amazing things, but at the same time, there are very real questions as to what constitutes "proof" any more.

    consider this: the hypothesis of the famous Riemann Zeta problem has been tested for trillions of different solutions, and it has held true in every case. (If you want an explanation of the Zeta problem, look elsewhere, I don't have the time)

    Now that means that it's *probably* true, but nobody accepts that as mathematical proof.

    On the other hand, the classification problem for finite simple groups has been rigorously solved, but the collected proof (done in bits by hundreds of mathematicians working over 30 years) is tens of thousands of pages in many different journals. given the standards of review, it is a virtual certainty that there is an error somewhere in there that hasn't been found. So, again, the solution to this problem is *probably* right, but it has been accepted as solved.

    What's the difference between these two cases really? What's the difference between these and relying on computer proofs that are, again, *probably* right?

    In this light, the math of the late 19th century and early 20th century was something of a golden age, modern standards of logical rigor were in place, but the big breakthroughs were still using elementary enough techniques that the proofs could be written in only a few pages, and the majority of mathematically literate readers could be expected to follow along. These days proofs run in the hundreds of pages and only a handful of hyper-specialized readers can be expected to understand, much less review them.

    --
    In Capitalist America, bank robs you!
    1. Re:new facet of an old issue by qbwiz · · Score: 2, Interesting

      On the other hand, the classification problem for finite simple groups has been rigorously solved, but the collected proof (done in bits by hundreds of mathematicians working over 30 years) is tens of thousands of pages in many different journals. given the standards of review, it is a virtual certainty that there is an error somewhere in there that hasn't been found. So, again, the solution to this problem is *probably* right, but it has been accepted as solved.

      Wouldn't this be a good use for the computer, then - attempting to verify these disjointed proofs and combine them into one unified whole?

      --
      Ewige Blumenkraft.
    2. Re:new facet of an old issue by I+Be+Hatin' · · Score: 5, Insightful
      consider this: the hypothesis of the famous Riemann Zeta problem has been tested for trillions of different solutions, and it has held true in every case. (If you want an explanation of the Zeta problem, look elsewhere, I don't have the time) Now that means that it's *probably* true, but nobody accepts that as mathematical proof.
      On the other hand, the classification problem for finite simple groups has been rigorously solved, but the collected proof (done in bits by hundreds of mathematicians working over 30 years) is tens of thousands of pages in many different journals. given the standards of review, it is a virtual certainty that there is an error somewhere in there that hasn't been found. So, again, the solution to this problem is *probably* right, but it has been accepted as solved.
      What's the difference between these two cases really?

      That one claims to be a proof and the other doesn't? You simply can't prove the Riemann Hypothesis by testing trillions of numbers (though if you find one case where it fails, you have disproved it). As a simple example, I can find trillions of numbers whose base-10 expansion is less than a googolplex digits long. Does this mean that all integers have this property? Of course not... So even if all of the calculations are right, you still don't have a proof.

      On the other hand, the classification of finite simple groups does claim to be a proof, and if there are no errors, it is a proof. You're right that there are probably errors, but these may be only minor errors that can be fixed. At least no one seems to have found evidence that the proof is completely flawed yet. But it's certainly possible that someone will find an insurmountable error in one of the proofs. There have been cases of propositions that were "proved" true for more than 80 years before a counterexample was found.

      What's the difference between these and relying on computer proofs that are, again, *probably* right?

      Again, it depends upon what the computer is trying to show. The computer proofs I'm familiar with are ones where the methods are documented, it's just that the computations are too tedious to do by hand. So you can read the proof and say "modulo software bugs, it's a proof". And then it works the same as science: anyone who wants to can repeat the proof for themselves, and see that they get the same answer. As more people validate these results, the likelihood of bugs goes down exponentially, and the likelihood of the proof being accepted increases.

      --
      I know god exists. I read it on the internet, so it must be true.
    3. Re:new facet of an old issue by Anonymous Coward · · Score: 2, Interesting

      For those who don't understand why mathematicians are always striving for better than "probably true", the Mertens Conjecture [Mathworld] is the commonly given example. It was thought to be true. As the Mathworld article notes, as late as 1985, arguments were made that there was no counter-example for numbers less than 10^20 or even 10^30. However, in 1987, someone proved a counter-example DOES exist. It is somewhere between 10^12 and 10^65. In short, you could process billions of integers and find that the conjecture held, leading you to believe it was "probably true". But it is actually false.

    4. Re:new facet of an old issue by illuminatedwax · · Score: 2, Interesting
      Better example of why finding trillions of correct values for the Riemann hypothesis:

      The Mobius function is a number theoretic function with the value:

      M(n)= 1 if n=1
      = -1^r if n = p1*p2...*pr where p1-pr are distinct primes
      = 0 otherwise.

      A mathematician, Frantz Mertens, conjectured in 1897 that sum(M(k), k=1 to n) < sqrt(n). This conjecture has been proven by computer for all n < 10^9. However, in 1984, Andrew Odlyzko and Herman te Riele proved that this conjecture was false for some n <= 3.21 * 10^64.

      This is why we have to prove the Riemann hypothesis. Not only does the problem quit bugging us, but we learn new things along the way. When Andrew Wiles proved Fermat, proving Fermat gave no immediate benefit, but it also proved an important conjecture about elliptical curves and I believe it provided the mathematics community with Galois theory.

      (IANAM.)

      --Stephen

      --
      Did you ever notice that *nix doesn't even cover Linux?
  14. Rumsfeld, anyone?-Overload. by Anonymous Coward · · Score: 3, Funny

    ???
    BOOM!

    "Cleanup in aisle 10"

  15. maturity by jdkane · · Score: 2, Insightful
    whether technology spurs greater achievements by speeding rote calculations or deprives people of fundamentals.

    As far as calculator example goes, I believe a person should understand the fundamentals before using the calculator. Don't give a power tool to a kid. Somebody with an understanding of the fundamentals can wield the tool correctly and wisely whereas some cowboy is just dangerous. The old saying comes to mind "know just enough to be dangerous". As far as those oranges in the article, well somebody had better figure out a way to confirm the computer answer, without having to go through the exact same meticulous steps. Don't put your trust in technology without the proof to back it up, because technology built by people is prone to error. Now I'm sure the orange problem won't cause harm to anybody, however I hope I never read such an article about a nuclear power plant!

  16. Re:Are Computers Ready to Create Mathematical Proo by superpulpsicle · · Score: 2, Informative

    The question is whether the people setting up to create mathematical proof are ready themselves?

    So many times I see people use programs like MAPLE to show something mathematical, and it ends up a disaster.

    Problems is the brain on the chair, not brain on machine.

  17. I don't see what the big deal is by ameoba · · Score: 4, Interesting

    I don't see what the big deal is; not only is the general problem of proving mathematical statements undecidable (even without considering Godel's theorem) but even solvable problems require a lot of human intervention to get solved. Most problems (ie - examples out of math textbooks) aren't going to come up with a proof in any reasonable amount of time by simply dropping it into a theorem prover and pushing "go".

    "Automated theorem proving" is less an automatic process (like you'd get with an automated production line) and more of a mechanical assistance to the job (like using a fork-lift to move heavy things faster than you could by hand).

    It not only takes work to convert a problem into a good representation, but then you have to structure the problem statement in such a way that a theorem prover can make optimal use of it. Often times, you're forced to, upon following the output, prove lemmas (sub-proofs).

    Then, when you finally get a proof, you get the joy of trying to simplify it to something that -can- be understood by a person; again, this is part of the process that can't really be automated well.

    --
    my sig's at the bottom of the page.
  18. change the title by NotAnotherReboot · · Score: 4, Insightful

    Change the title to: "Are Computers Able to Verify Mathematical Proofs Beyond All Doubt?"

  19. Godel? by Anonymous Coward · · Score: 2, Informative

    Doesn't the Godel incompleteness theorem say they can't?

  20. Wait, I know this one... by bomb_number_20 · · Score: 4, Funny

    The answer is left as an exercise for the reader.

    --
    That's ok, Jesus likes me anyway.
  21. indeed by rebelcool · · Score: 4, Insightful
    On a similar topic, today I attended a lecture by Tony Hoare on compilers that can generate verified code and tools that guide the human programmer into designing programs that can be easily validated (from the compiler's stance). One very good question raised afterwards was, well how do you know you can trust the compiler generating the verified program?

    Though Dr. Hoare danced around that question a little, presumably that aspect of the project would have to be done by hand, a monumental task to say the least.

    --

    -

    1. Re:indeed by Squeamish+Ossifrage · · Score: 4, Informative

      At least some provable properties can be "pushed" through the compilation process all the way to the resulting object code. If you're interested, you can look into proof-carrying code and typed assembly language (papers by Necula, Appel, Walker, Zdanzewic, Crary and a cast of thousands.)

      The resulting proofs are still hairy enough that they have to be checked by machine, but the size and complexity of the proof-checker is much less than that of the compilation toolchain. That means that while there's still some code that has to be trusted, it's much less. Here's my informal scariness hierarchy:

      Normal model (you have to trust everything) > type safe languages (you have to trust the compilers / interpreters) > proof-carrying code (you have to trust the proof-checker*).

      If you haven't already, you should definitely read Ken Thompson's Turing Award lecture, "Reflections on Trusting Trust" here.

      * - Pedantry point: If you're talking about Necula's original PCC work, you also have to trust the verification condition generator, which is some fairly deep voodoo. Appel's Foundational PCC addresses this to a signficant extent.

    2. Re:indeed by Squeamish+Ossifrage · · Score: 5, Interesting

      No! Definitely not! Really! :-)

      Most faults are software problems, not hardware, so having different machines won't help. Further, interestingly, most major software faults (at least, of the sort that make it through serious testing) tend to be conceptual problems, not coding ones, and different people tend to make the same mistakes. This means in practice that even when you have completely independent software implementations (called n-version programming), they're frequently all wrong in the same way at the same times. See the famous Knight & Leveson paper.

    3. Re:indeed by maxwell+demon · · Score: 4, Interesting

      While the article spaks about intentional errors, I could imagine the same to be true for bugs (while introducing a self-replicating bug by accident is unlikely, I'm not sure if it's unlikely enough to never occur).

      Say, an optimizer is buggy. Say, in a certain line of code in the compiler, there's a '>' instead of a '<' sign. Unfortunately, this causes, under certain, rare conditions, the optimizer to miscompile '<' into '>'. Now, since triggering that bug is rare, it goes unnoticed for a while, and the buggy compiler is installed as default compiler for further development.

      Now, at some later time, the bug is found, a developer looks at the code and finally finds the error. He replaces the '>' by '<' in the hope of fixing the bug. Unfortunately, he doesn't recognise that this very comndition now triggers the bug, having the compiler internally replacing '<' to '>' again, replicating the bug again.

      Now, the test case will show that the bug is still there, but the developer will simply not find the bug in the code. After all, the bug isn't in the source any more. It's only there in the compiled program. At some later time, though, it might magically disappear by some unrelated change nearby, which causes the bug not to be triggered any more.

      --
      The Tao of math: The numbers you can count are not the real numbers.
  22. making hard things easy... by Polo · · Score: 3, Funny

    Mathematics is just Symbol Manipulation. I suspect computers are pretty good at that.

    Also, chess is just Pattern Matching... I don't know if humans have the edge there or not. ;)

    1. Re:making hard things easy... by Anonymous Coward · · Score: 2, Insightful

      Yes. Mathematics is just Symbol Manipulation. And so is science, and poetry, and everything else written.

  23. regfree link by werdnapk · · Score: 3, Informative
  24. Damn, I should have submitted this by Pedrito · · Score: 2, Insightful

    My father sent this to me first thing this morning. I told him that I didn't think that rigorous mathematical proofs should be based on software either in whole or in part. All software of any complexity is inherently buggy. That doesn't mean that rigorous mathematical proofs are flawless by nature. That's why they have peer review. But peer review on software still isn't always sufficient.

    Another issue is that you're then excluding any mathematicians who aren't also fairly adept programmers, from really understanding your proof.

    All of this said, computers are necessary to do math these days and I think mathematicians should make use of them. I just don't believe we've reached a level of maturity in software development that meets the stringent requirements of mathematical proofs.

  25. Why not.. by Sir+Pallas · · Score: 3, Interesting

    ..if you can prove the program. I know that a lot of people look down on axiomatic semantics and model checkers; but I also know some people that started in that area a long time ago that still believe in it, and even more that are trying to get faculty appointments out of this rebounding field. If you can prove a program does what you expect it to and it, it turn, can be shown to prove what you really wanted, I don't see the problem. Maybe some of our theoretical mathematicians just need a dose of practical computer science.

  26. The stack might get a bit deep, but... by Odin's+Raven · · Score: 4, Funny
    'Can we trust the darned things?' 'Can we know what we know?'

    The obvious solution is to have the computer create a new proof that shows that the algorithm it used to create the original proof is, in fact correct.

    And to prove that the proof of the proof can be trusted, have the computer create a proof of the proof of the proof.

    And to prove that the proof of the proof of the proof can be trusted, ...
    --
    A marriage is always made up of two people who are prepared to swear that only the other one snores.
  27. A rather timely Slashdot fortune by Anonymous Coward · · Score: 2, Funny
    What I see on the bottom of the page as I read this topic discussion is:
    The truth of a proposition has nothing to do with its credibility. And vice versa.
  28. Wrong Summary by DougMackensie · · Score: 2, Informative

    This story and this issue are not about whether or not the mathematical community trusts a computer created proof. The issue is whether or not the community can trust the human behind the computer to create a computer program/system that is "flawless enough". Issues and bugs may arise, and the community can't trust that these issues will 1. be found and 2. be severe enough to affect the validity of the proof.

  29. Re:I don't care by Vancorps · · Score: 2, Insightful
    That is certainly true, so if a computer screws up portion in the middle and the answer still comes out correct then the end result is the same.

    Another post mentioned that computers could come up with the proofs but it would be too hard for a human to verify. At what point can be start to both trust the output and to build upon that trusted output by further trusting future output. It could be an interesting time in which we don't understand how things are done but we are able to do them none the less. It all comes down to the question, how much do you want to trust a machine?

  30. Verification of computer proofs is a pain... by briaydemir · · Score: 3, Interesting

    The problem with computer generated proofs is that in order to trust the result of the computer, you have to trust:

    1. The program(s), as source code, that generated the proofs.
    2. The compiler(s) that turned the source code into something executable.
    3. The hardware that ran the programs.

    And of course, our understanding of the hardware depends on how accurate our understanding of the laws of physics is. Any mistake in either the source code, compiler, or hardware, and potentially the proof produced is incorrect. That's an awful amount of stuff you have to check just to make absolutely sure the computer is correct. Then, consider how many bug-free pieces of software you've encountered. ... Yeah, I can see why mathematicians would not trust computer generated proofs.

    Of course, people are not infallible either, but that's well known and expected. It's all about how much uncertainty people are willing to accept.

  31. a mathematician's perspective by jockeys · · Score: 5, Interesting

    as a graduate in the fields of mathematics, i spent a large portion of my five undergraduate years doing proofs. there are a great many ways to prove things, sometimes applicable sometimes not. (e.g. using inductive proofs for numeric theorems is all well and good but completely useless for any sort of ring-theory or spatial proofs)

    there are also several levels of depth for proofs, ranging from "i've found a counter example so i can write the whole thing off as garbage" to "i have exhaustively and rigorously proved this starting with the basic axioms of number theory and worked my way on up"

    the latter is really the only acceptable way to prove anything seriously. sometimes when you are reworking an already- done proof to illustrate a point, other mathematicians will allow a bit of latitude when it comes to cutting corners, but for a proof as far-reaching as the one in the article, i would only be interested in a "rigorous" proof, that is, one that started with the foundational tenets of mathematics and combined those to form and prove other postulates, etc. very much a form of abstraction, not unlike large development projects.

    the problem arises when one (or several) humans have to be able to objectively check the whole thing. to use my prior example of a large development project, no one developer at microsoft understand the whole of windows. it's too big for a single human to understand. each developer knows what he needs to do to complete his part, and so on and so forth.

    traditionally, for proofs, a single mathematician (or a small group) would hammer out the whole proof, so the level of complexity remained at a human-understandable level. (even if tedious) my concern, as a mathematician, with using an automated solution would be the rapidly growing order of complexity needed to properly back up increasingly complex proofs. as stated in the article, it's like trying to proofread a phonebook. (only, you must also consider that for every element of the proof (a particular listing) there are several branching layers of complexity (fundamental, underlying proofs many layers deep) underneath. this gets more complicated in an exponential fashion) obviously this approach will only remain human-checkable for relatively small problems. (programmers: think of some horrible nondeterministic- polynomial problem like the "traveling salesman" problem. systems, like humans, are a finite resource, but if you increase the size of the problem, the complexity will quickly grow far beyond your ability to compute. large proofs suffer from the same difficulties, if not quite as concrete and pronounced as NP algorithms)

    in closing, i would have to agree that proofs, no matter the effort and computing time put into them, really should not be viewed as being as rigorous as those provable "by hand" and human- understandable, even if the computer has arrived at a satisfactory conclusion, because we have no way of KNOWING if the computer has built up the proof correctly, except that it says it has.

    --

    In Soviet Russia jokes are formulaic and decidedly non-humorous.
    1. Re:a mathematician's perspective by Tom7 · · Score: 4, Insightful

      because we have no way of KNOWING if the computer has built up the proof correctly, except that it says it has

      Sure we do -- typical theorem provers spit out a proof that can be checked by hand (god forbid), or else checked by a simple procedure. Understanding that a theorem prover is implemented correctly is tough, but understanding that a checker is implemented correctly isn't. I trust such proofs more than I trust hand-checked proofs, because humans are more susceptible to mistakes than computers are.

  32. Re: . . . As we know it. by Bastian · · Score: 4, Interesting

    I think the "as we know it" is the key word here. It creates a new juggling act that teachers have to deal with. On one hand, calculators are extremely useful for the things at which humans are error prone. If students can use calculators or Mathematica or something, they can check their arithmetic much more reliably, which is great for isolating problems with learning concepts from basic mathematical errors. Granted, some people don't see this as a bonus since it's good to be able to do arithmetic reliably without aid. For smaller numbers I agree, but in the real world people use calculators for arithmetic with numbers that have a lot of sig figs. Making students do this arithmetic by hand is just distracting them from learning the concepts they are supposed to be learning.
    On the other hand, many students are prone to using these devices and applications as crutches and try to get away with doing things like using their calculator's implementation of Newton's Method instead of solving the problem themselves.

    Some professors have found solutions to this problem, others havent. When I was at college, I think our math department had achieved a pretty good level of harmony with Mathematica - we were expected to do a lot of stuff by hand or in our heads - Gaussian elimination, for example - but in order to make the math seem useful, we were also exptected to be able to solve real-world problems with the stuff we learned. Not contrived "real-world" problems from your high-school textbook, but stuff like interpreting large and dirty scientific datasets where the specific technique we would have to use to solve the problem was something we could figure out, but not something that had been explicitly laid out by the textbook or in lecture. We had to apply the concepts we had learned to figure out the problem, but there was no way we were going to chug out that arithmetic by hand - when was the last time you tried to work on a 16x16 matrix using a pencil and paper? How about a 100x100 one?

  33. Mathematics is Human by Traser · · Score: 2, Troll

    Mathematics is one of the most intensely human of human endeavours. Everything in it is a production of the human mind entirely. Yes, the real world can sometime lead us into an interesting area of inquiry, but at its core the uncoverings of truth from axioms is a human endeavour.

    A computer can be a useful tool (I'll be doing computational graph theory this summer), but it is not human. It does not have the ability to hold the possiblities of ideal forms within it and understand. It does not think.

    The use of numeric methods to solve applied problems, or symbolic methods to pure problems is good and useful, but it does not constitute proof.

    A human being, given an understanding of the underlying mathematics, must be able to go through the proof step by step, and see that, from the givens, the conclusion is inevitable.

    I don't accept the Four-Colour theorem as proven true. I strongly suspect it to be so, but my suspicion does not truth make.

    The Riemann hypothesis, on the other hand, is much, much further from being proved then the Four-Colour Theorem. Yes, millions of zeroes have been checked...but there are infinitely many zeroes, and all it takes for it to be false is for ONE of those zeroes to fall off the Re=1/2 part of the complex plane.

    If I were giving odds, then millions divided by infinity is awfully close to zero.

    --
    Insanity is contagious. - Yossarian
  34. You beat me to it by UberQwerty · · Score: 4, Informative

    I professor showed me the Robbins Algebra proof a while ago. I was going to link here, but first I searched the page for (Score:5, Informative), and there you were :)

    Here's an excerpt:

    In 1933, E. V. Huntington presented [1,2] the following basis for Boolean algebra:
    x + y = y + x. [commutativity]
    (x + y) + z = x + (y + z). [associativity]
    n(n(x) + y) + n(n(x) + n(y)) = x. [Huntington equation]

    Shortly thereafter, Herbert Robbins conjectured that the Huntington equation can be replaced with a simpler one [5]:
    n(n(x + y) + n(x + n(y))) = x. [Robbins equation]


    Robbins and Huntington could not find a proof. The theorem was proved automatically by EQP, a theorem proving program developed at Argonne National Laboratory.

    --


    PUBLIC SPLIT ON WHETHER BUSH IS A DIVIDER -CNN scrolling banner, 10/15/2004
  35. Re:4 color map problem by Old+Wolf · · Score: 2, Funny

    Come on, this is just comparing Appels and oranges

  36. identity by chocolatetrumpet · · Score: 2, Funny

    No matter what the proof, don't we still have to accept blindly on faith that A=A?

    Sure, it seems highly probable but.. I just.. I guess I'm a skeptic. All of logic seems like a joke to me, as long as this one little potentially huge loophole looms in the background...

    --
    Spoon not. Fork, or fork not. There is no spoon.
    1. Re:identity by sbaker · · Score: 4, Informative

      Some things have to be taken as Axioms. A=A is one of them. All the things you prove that rely on A always being equal to A can be taken as true PROVIDING you accept that axiom. We like to pick axioms that we have a gut feel 'must' be true - but you can do interesting mathematics by denying some of those axioms and see where they take you. The classic geometric case of denying that parallel lines never meet produced a whole range of interesting geometries that don't exactly represent the real world but none-the-less have interesting and useful consequences.

      So - when you come across a theorem that you can't prove but are pretty damned certain is true - you COULD choose to simply make it be an axiom. The problem is that the theorems you are subsequently able to come up with are only as reliable as your initial assumption of that axiom.

      If your axioms eventually turn out not to match the real world - then all you have is a pile of more or less useless theorems that don't mean anything for the real world.

      It's therefore pretty important to stick with a really basic set of axioms to reduce the risk that an axiom might turn out not to be 'true' for the real world and bring down the entire edifice of mathematics along with it.

      If we ever found some sense in which A!=A then every single thing we thought we knew about math would be in doubt.

      --
      www.sjbaker.org
    2. Re:identity by illuminatedwax · · Score: 3, Interesting
      You should definitely read Carroll's Paradox. Lewis Carroll had thought about this exact problem. I think that assuming logic on faith, however, is an acceptable step in human endeavours.

      --Stephen

      --
      Did you ever notice that *nix doesn't even cover Linux?
  37. Re:The dawn of a new age of Math... and Science! by ParadoxicalPostulate · · Score: 5, Insightful


    once upon a time, only advanced mathematicians knew calculus, but now we learn it in high school. Just wait until warp theory is an entry level college engineering course

    Once upon a time, the majority of adult males knew how to trap a rabbit (or similar creature), gut it, skin it, start up a fire, cook it, and eat it.

    I don't.

    Heck, I couldn't even look up at the sky at night and tell you which way was north.

    Once upon a time, most people could.

    All I'm saying is that the amount of knowledge and skills the average human being can possess will not increase expontentially over time (barring artificial manipulation). We gain new skills as a population and lose old ones.

  38. Flyspeck Project by harlows_monkeys · · Score: 4, Informative

    Here's a link to the Flyspeck Project, briefly mentioned at the end of the article, which aims to give a formal proof of the theorem.

  39. Canada's former prime minister's "proof" by Anonymous Coward · · Score: 3, Funny

    "I don't know, a proof is a proof. What kind of a proof is a proof? A proof is a proof and when you have a good proof it's because it's proven."

    (PM Jean Chretien, when asked what kind of proof he would need of weapons of mass destruction in Iraq before deciding to send Canadians along on the Bush invasion-September 5th on CTV news)

    1. Re:Canada's former prime minister's "proof" by Photar · · Score: 2, Informative

      If only he had the power of the internet.

      --
      He who knows not and knows he knows not is a wise man. He who knows not and knows not he knows not is a fool.
  40. Absolutely -- and this is the future by Tom7 · · Score: 2, Interesting

    What strange timing -- I just saw a talk this morning from Hales at CMU about his work on formalizing the Kepler conjecture ("theorem") in HOL Light.

    I can understand not wanting to trust a big piece of C code that purports to check a huge number of cases of a proof doing numerical analysis. It took 6 years of 4 people trying to verify his computer proof of the Kepler conjecture--before they gave up. If a program is that hard to believe, then it does indeed deserve lesser status than a handwritten proof that can be checked by mathematicians in shorter time.

    On the other hand, there are other computer tools that we really should trust, and that are revolutionizing mathematics. The idea is simple: write your proofs in such detail that they can be mechanically checked by a simple (easy to verify) procedure. This is much better than paper proofs, because the potential for human error is minimized. (I don't think anyone will argue that published proofs have often been wrong, and the proofs have not been caught by the peer reviewers!) Since it's really, really bad to believe wrong proofs, there's a very real benefit that is offset by the sometimes tedious work necessary in formalization.

    That's what Tom Hales is doing with flyspeck, and I think it is the future of mathematics. (In fact, I have recently become addicted to mechanizing my own proofs in Twelf--it's not only immensely satisfying, but it helps me sleep better at night and makes for stronger papers.)

  41. Ok I am always confused about the difference. by efuseekay · · Score: 2, Interesting

    I know I am splitting hairs (but who isn't in this kind of discussion), but I can't wrap around my head around the difference DK and DD to the person in question .

    What i mean is,effectively not knowing you know something is the same as not knowing you don't know something, since you are ignorant of it anyway. Of course, one can remind me that I know something, (e.g. "You idiot! That's just the Laplace-Beltrami operator you learned in class!"), but then to me I am now KK, not DK.

    Maybe DK is just a very confusing way of saying "forgot for a moment".

    Ok, my head is spinning again. Maybe the hairs are too fine to split anyway :P.

    --
    Mode (3) smart-aleck mode. Press * to return to main menu.
    1. Re:Ok I am always confused about the difference. by Forgotten · · Score: 4, Insightful

      Most people probably knew the "four quadrants of knowledge" thing, but didn't know they knew (DK). That is, they have enough to put it together, but have probably never put it into words before. Intuitive knowledge is one way of putting it. The bulk of most people's knowledge probably falls into this category, which is fine - language is often overrated as a conduit of knowledge (not that it's not incredibly useful and important, but other means exist and are constantly used).

      I don't actually believe particularly firmly in that model, though, because I don't agree with the D-K dichotomy that underlies it. It's your usual classical Greek quadrant, which means it springs from a dual dichotomy, or in this case a dual-aspect single one. Dichotomy (or even one-dimensional spectra) is not the only way to look at things, but it is a dangerously compelling model - that is, when people have been presented with a dichotomy, they typically become unable to consider without it. And the defence of a dichotomy is usually a tautology - I mean it's obvious, isn't it, you either know something or you don't? ;)

      Still useful and interesting if you can get it out of your head when needed, though.

    2. Re:Ok I am always confused about the difference. by Photar · · Score: 4, Informative

      I believe its called the fallacy of the false delemma.

      --
      He who knows not and knows he knows not is a wise man. He who knows not and knows not he knows not is a fool.
  42. an Eternal Golden Braid by jmagar.com · · Score: 2, Informative
    I'll keep this short, for I have little more to offer than what has already been said. But if this sort of thing (mathematics, proofs, and the beauty within) interests you, then you should really check out this book:


    Godel, Escher, Bach: an Eternal Golden Braid


    I am only half way through it, and it handles this topic far more gracefully than the original article. Very entertaining if you happen to be a math, music, or art geek. Strange mix, but Douglas Hofstadter really nailed it.

  43. They're asking the wrong question by starseeker · · Score: 3, Insightful

    'Can we trust the darned things?' 'Can we know what we know?'

    It's not an issue of can we trust them, at least not in general. (We won't go into the question of current machines - I'll agree they're generally not there for rigorous proofs.) We're going to have to either trust some form of computation aid in proof work, or throw up our hands and abandon the field - the human brain and lifespan impose definite limits beyond which we cannot go without aid, and since I can't think of any limit human beings have willingly accepted as a group somehow I doubt this will be the first. So, instead, the question should be

    "How do we create computers we can trust?"

    If that is impossible, then that's it. Mathematics will be come like experimental high energy physics - 20 years effort by 100s of people to achieve one result. But I'm not ready to concede that its impossible. I know it is provable that computers can't solve all problems in general, but the same proof indicates humans can't either. The question I'm curious about is whether the behavior of a computer is too general to be attacked by useful proof methods. Most actions taken with a computer assume a definite action and a definite outcome (spreadsheets and databases, for example, do not do novel calculations but perform the same operations on well defined data.) Mathematical proof is a different question, but the ultimate question is whether a properly designed and built computer (i.e. built as rigorously as possible in a technical and algorithmic sense) would be completely unable to handle problems that are interesting to human beings in the proof field. That is a completely different question from generality statements, and from the standpoint as computers as a trustworthy tool I think it is the more interesting one.

    --
    "I object to doing things that computers can do." -- Olin Shivers, lispers.org
  44. Proving the prover? by jeduthun · · Score: 3, Interesting

    Perhaps I'm missing something here, but I think the approach of verifying the validity of the proofs that come out of the kind of system described in the article is fundamentally the wrong approach.

    Instead, mathematicians ought to focus on formally proving the proof generator. If it could be fomally proved that the proof generator only generated valid proofs, we could automatically trust all the proofs that it generated. Program proof and verification is a complex topic, but it's a quickly maturing area of CS.

  45. Wrong question. by ilyag · · Score: 2, Insightful

    The question should not be whether computers can calcualte flawlessly - that's obviously wrong. The question is whether the probability of all the different configurations of computers consistently giving the same wrong answer to a problem is greater than the probability of all the human mathematicians agreeing on the same wrong answer. To me, it seems obvious that the computers are better off...

  46. Re:The dawn of a new age of Math... and Science! by bluGill · · Score: 2, Insightful

    Insightful up to the last paragraph. Sure I can only learn so much (knowledge and skills). Becoming good at playing the guitar means a trade off, and perhaps by making that choice you don't learn to skin rabbits, fly airplanes, and so on. Yet some have done several of the above. There is enough knowledge that you cannot learn it all. As a population we do not lose old skills, at least not near as often as we learn new ones.

    Some things take years to learn, some take minutes to learn and years to master, and some take just minutes to learn. Some are worth teaching everyone (reading for example), some are worth learning despite no practical use (playing guitar for example), and some are hobbies that a few people learn for the fun of it (skinning rabbits). Few skills are lost over time though, and now that reading is universal less are lost because those who know can write down for latter use.

    Look around and you will find a few people who can tat, make chain mail, build a bark canoe and so on. All useless skills in this modern world, but kept alive because someone made it their hobby. I've seen books on all of the above, and many more.

    If the doom sayers worst perdictions come true and you are one of the few people to survive [whichever disaster is in vogue today] you can go to a library and get books for the skills you need. Find someone to have kids with, and you are likely to pass reading and simple math onto them, and they to their kids. Eventually civilization will return with population, and your many times great grandkids will have an advantage in that they can read our books to tell them what works so they don't make the mistakes we did.

  47. Humans behind the scenes by dysprosia · · Score: 2, Informative

    For some cases of proof solving, a human is often behind the scenes, and has reduced the number of cases that a computer has to check from infinity to say 10^25 or some other large, but finite number.

    Computers nowadays can handle symbolic calculations and prove identities and likewise, but for identifying what is interesting to have proved or not, a human may still be there with interpreting that, no matter how sophisticated computers or software can get...

  48. Risc Institute: Theorema by elmartinos · · Score: 3, Informative

    The people at the Risc Institute are creating cool stuff like Theorema, which helps in automatically proofing things. Some of these people teach math at a university in Hagenberg where I got the chance to see this thing in action, it is really amazing how well this works.

  49. Re:Create vs. Verify (Chicken or Egg?) by gugg · · Score: 2, Interesting

    About 20 years ago, I worked for a company near Boston, and played in a co-ed softball league made up of teams from other companies in the area. One of the teams had an extremely attractive third basewoman, who was also quite friendly, which I discovered during a game where I had actually made it to third base. At the beer hall we went to after the games, I asked her what she did; she told me she was the head of Q&A for a product that would supposedly produce provably correct programs. You used some kind of GUI to draw something like a flowchart, typed in a few constraints, and then clicked on a button, and out would come bug-free code (in Fortran or something). "Sounds cool" I said, but she laughed and said that the development team had been having a really hard time getting the bugs out of the tool's parser. For the next few weeks, the joke was about the shortsightedness of her company's management - "Why don't they just do the obvious thing, and use their tool to generate the code for the parser?". They never were able to get all the bugs out, and went out of business a short time later.

  50. Charles Babbage and Meta-Logic by ingenuus · · Score: 3, Insightful

    "On two occasions, I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question."
    -- Charles Babbage (1791-1871)

    Computers only do what they are told (excepting "hardware failure", which is not the topic).

    Shouldn't the validity of computational proofs be able to be determined by proving the meta-logic of the solver?
    i.e. proving that a strategy for finding a proof is valid (and therefore trusting its results).

    Maybe those wary mathematicians are just unaccustomed to working on a problem meta-logically, and prefer to find proofs directly themselves (with the meta-logic being defined solely within their own minds)?

    In such cases, perhaps peer review should not require human verification of a computational proof, but rather another independent meta-logically valid computational proof?

  51. Re:What did godel say? by term8or · · Score: 2, Informative

    Hm. I always thought that Godels theory actually goes further than "There is no proof for this statement.".

    We know that given any collection of nontrivial axioms there will always be a statement that is consistent with all axioms and valid proofs that cannot be prooved or disprooved within that set of axioms. In other words, no matter how many axioms we select no nontrivial mathematical system with a finite number of axioms is complete. Secondly, as you said there are mathematical constructs that can not be proved or disproved, and so it is impossible to show that all existing proofs are consistent with the chosen axioms.

    --



    "As a writer / novelist you might want to spellcheck your sig. :) " - AC
  52. more than people by hak1du · · Score: 2, Insightful

    The mathematical literature is full of errors, oversights, invalid proofs, unstated assumptions, and probably even a certain share of deliberate fraud. See Lounesto's misconceptions of research mathematicians for one expert digging into the mathematical literature.

    Computers are far better at ferretting out oversights, missing assumptions, and making sure that every t is crossed and i is dotted. If a software system for doing proofs has shown itself to be fairly reliable on a bunch of samples, I'd trust it a lot more than I'd trust any working mathematician to carry out a complex proof correctly.

  53. peer review by Kent+Simon · · Score: 2, Insightful

    People attempting the proofs are no less vulnerable to making mistakes than those who wrote computer software to develop the proofs. Thus a system to verify the proofs should be in place for both groups of people. Any person working on a doctoral discertation will have their work reviewed by a board. Any proof generated by a computer shout too be reviewed by a board before it can be considered correct. I don't see where the issue is.

    --
    Kent Simon Multitheft Auto