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The End of Mathematical Proofs by Humans?

vivin writes "I recall how I did a bunch of Mathematical Proofs when I was in high school. In fact, proofs were an important part of Math according to the CBSE curriculum in Indian Schools. We were taught how to analyze complex problems and then break them down into simple (atomic) steps. It is similar to the derivation of a Physics formula. Proofs form a significant part of what Mathematicians do. However, according to this article from the Economist, it seems that the use of computers to generate proofs is causing mathematicians to 're-examine the foundations of their discipline.' However, critics of computer-aided proofs say that the proofs are hard to verify due to the large number of steps and hence, may be inherently flawed. Defenders of the same point out that there are non computer-aided proofs that are also rather large and unverifiable, like the Classification of Simple Finite Groups. Computer-aided proofs have been instrumental in solving some vexing problems like the Four Color Theorem."

26 of 549 comments (clear)

  1. Critics Reaction... by Suhas · · Score: 4, Insightful

    ...From TFA if a computer is used to make this reduction, then the number of small, obvious steps can be in the hundreds of thousands--impractical even for the most diligent mathematician to check by hand. Critics of computer-aided proof claim that this impracticability means that such proofs are inherently flawed.

    So basically what they are saying is that if the proof is too long to be checked, then it is flawed? WTF?

    1. Re:Critics Reaction... by damieng · · Score: 5, Insightful

      Yes, thats right.

      If you can't independently examine and verify your "proof" then how can it be considered proof of anything?

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      [)amien
    2. Re:Critics Reaction... by wwahammy · · Score: 3, Insightful

      Flawed in the sense it can't be peer reviewed to be "proven." It could be true but because it can't be independently verified then its not a proof because you can't prove it. Now whether this is truly a situation where a proof is unprovable or just people reacting to the thought of their profession being eliminating by technology is another debate entirely.

    3. Re:Critics Reaction... by MonMotha · · Score: 3, Insightful

      A mathematical proof is nothing but a manner of convincing someone (other mathematicians) that what you assert is indeed correct, given the following presumably known, accepted as true, or otherwise previously proven "things". The whole point of a proof is that someone else knows wtf it is talking about.

      I could assert that 2+2=4. You may believe me, but have I really proven it to you? Not yet, so you don't need to believe me. If I instead say that the the cardinality of the union of two disjoint sets, each of cardinality 2, is 4, then I've (sort of) showed you that 2+2=4, assuming you accept my definitions of disjoint sets, set union, and set cardinality (which presumably I've proven elsewhere, or taken from some other source). Now do you believe me that 2+2=4?

      I could assert anything. You may or may not know if it's true. A proof is just something to back up my assertion and convince you that I'm right. Hence, if a proof is unintelligable, it's pretty darn worthless.

    4. Re:Critics Reaction... by Zork+the+Almighty · · Score: 4, Insightful

      Whether or not something is a proof is entirely our distinction to make. We choose the axioms on which the proof is based. To paraphrase Bill Klem (a famous umpire): when asked whether a pitch was a ball or a strike, "It isn't anything until I call it".

      --

      In Soviet America the banks rob you!
    5. Re:Critics Reaction... by g1t>>v · · Score: 5, Insightful

      In general, it is impossible to prove that such a 'formal logic validator' is correct since it is not possible to prove that an axiom system is correct inside that axiom system (one of Goedel's theorems). So if you would find a proof that your validator is correct, you'd have used reasoning techniques outside the logic of your validator, and do you believe those? (If so, why didn't you include them in the validator, since now your validator clearly does not support a reasoning technique you considered valid in the first place!)

      Basically, at a certain point, you just have to "believe" that your axioms, logic, whatever you call it, is consistent. Because to prove it, you'd again need axioms, a logic, etcetera, ad infinitum.

  2. Creativity by Daxx_61 · · Score: 5, Insightful

    Much of mathematics isn't just grunt power, there is also a lot of creative work going on there. Without humans to drive the computers doing the work in the right directions, it could take a long time before a computer would be able to get its proof - it simply doesn't know what it is looking for.

    I for one welcome our new robotic theorum proving overlords.

    --
    Quoth the server, "404."
    1. Re:Creativity by Zork+the+Almighty · · Score: 4, Insightful

      Without humans to drive the computers doing the work in the right directions, it could take a long time before a computer would be able to get its proof - it simply doesn't know what it is looking for.

      To some extent that's true, except in areas where human understanding has reduced mathematical proof to a mechanical process. For example, verifying algebraic identities, or even geometric proofs. A more advanced example is the Risch algorithm for elementary integration. It amounts to a proof that an integral either is or is not expressible in terms of elementary functions. Eventually we come to understand an area to such an extent that we can implement mechanical algorithms and move on. The proper role of the computer is to carry out these algorithms, so that we can use them to discover something else.

      --

      In Soviet America the banks rob you!
  3. If computers could write proofs... by John+Allsup · · Score: 4, Insightful

    Short, sweet, beautiful proofs of interesting and useful theorems, I would welcome them to do so with open arms.

    As a tool to produce vast quantities of precise logical porridge quickly, computers have no equal in today's world, yet that is not what real mathematical proofs should be about.

    Mathematical proofs should show short, clever ways of connecting otherwise disparate concepts that are only obvious in hindsight. This is where computers will always be weaker.

    --
    John_Chalisque
    1. Re:If computers could write proofs... by TuringTest · · Score: 3, Insightful

      Current AI doesn't show creativity at all. In theorem proving, 90% of the required creativity is already present in the stated goal (the theorem), the other 10% is the heuristics programmed to guide the automatic search.

      --
      Singularity: a belief in the "God" idea with the "demiurge" relation inverted.
  4. Seems simpler to prove proffs-by-computer by Anonymous Coward · · Score: 3, Insightful
    Simply prove the program correct; and all its outputs will be correct?

    To do that.... well, just make sure the program was designed by a correct computer.

  5. Computer _aided_ proofs by irexe · · Score: 4, Insightful

    Computer proofs, like the graph color proof, are not proofs that are completely generated by a computer. The computer is merely used to brute force a fairly large number of 'special' cases which together account for all cases. The construction of the proofing method is and will remain human work, lest we create AI that matches our own I.In short, they are computer aided proofs only.

    Further and more importantly, at this point we do not have and are not likely to have a machine that can prove any provable theorem (and fyi, not all truths in mathematics are provable!).

  6. Are computer-aided proofs really proof? by Mattb90 · · Score: 3, Insightful

    During my preparation for my interview to study Mathematics at Cambridge last year, one of the discussion topics that came up was computer-aided proof. Between the interview-experienced teacher, a school colleague who was also applying and myself, we came to the idea that computer-aided proof might not be proof at all, because proof for Mathematicans is the ability to reproduce the workings by yourself - it might take a very long time, but the idea should be that a human could dervive them in order for them to be considered true proofs of human concepts. Whether many in the Mathematical community in England take this view, I won't know until the end of the year when I hope to start my course - but based on this debate, it wouldn't surprise me if quite a few did.

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    Mattb90
    Editor, allaboutgames.co.uk
  7. No progress without understanding by Freaky+Spook · · Score: 5, Insightful

    I remember how much I hated learning alegebra, trig, calculus etc & how much the theory sucked, I never saw any point to it & loved it when I discovered my TI-83 could do pretty much everything.

    Although I discovered easier ways to do the arithmatic, I still knew the underlying theory of the equations & what the numbers were actually doing, not just what a computer was telling me.

    Students should learn this, they are the basic building blocks of a science that dictates pretty much everything on this planet & although they won't have a use for everything they are taught they will have enough knowledge to "problem solve" which is what most of high school maths is designed to do, it trains our brains to think logically & be able to work out complex problems.

    How are people going to be able to further phsyics, medicine, biology if they get into their respective tertiary courses without understanding the basic principals of all science & have to learn it all over again??

    Or what about when computers just won't work & things have to be done by hand??

    Its fair to integrate comuters into maths but not at the expense of the theory that makes us understand how things work, we should not put all our faith in technology just because its the easy thing to do.

  8. Re:Science by AI by Zork+the+Almighty · · Score: 4, Insightful

    Well at least in regards to math, I stongly doubt that this will ever be the case. Mathematics is developed over decades and centuries. With a few notable exceptions, it doesn't just fall out of the sky in textbook form. Most areas of math started out as a giagantic mess (ex; calculus, linear algebra, even geometry), and it has taken the work of countless researchers, authors, and teachers to distill and refine it. This process will continue, and it is inevitable that the subjects which baffle us today will be hammered out and taught to grade school students eventually. Well developed theory makes mathematics easier, and this in turn fuels new discoveries.

    --

    In Soviet America the banks rob you!
  9. Re:Godel/Turing/Cohen... by Hideyoshi · · Score: 3, Insightful

    No, they didn't "prove" any such thing - you've been reading too much Roger Penrose if you think so. There's absolutely no evidence that human minds have magical access to truths which formal systems don't; there once was a time when it was thought "obvious" that parallel lines could never meet, and it's still hard for many people to believe that there is no such thing as universal time.

  10. Blowhard critics could use a logic course... by geekpuppySEA · · Score: 4, Insightful
    However, critics of computer-aided proofs say that the proofs are hard to verify due to the large number of steps and hence, may be inherently flawed.

    Because if there's one thing that humans are better at than computers, it's performing large numbers of repeated steps. Flawlessly.

    --
    Intelligent Design: because MATH is HARD.
    1. Re:Blowhard critics could use a logic course... by mcc · · Score: 4, Insightful

      One could argue that if a proof ever contains repetitive elements, then this is a bad thing and you want to be adding some sort of abstraction to the proof anyway.

      Anyway, the problem isn't the ability for the computer to perform flawlessly, the problem is in our ability to accurately specify to the computer what we want it to do. It's the whole "fast working idiot" thing, mechanical perfection isn't much good if we wind up just directing the computer to perfectly, flawlessly do the wrong thing very quickly. We have enough trouble convincing ourselves real-world software is going to do what we wanted it to after it compiles; and in that case we at least have the advantage we can run it and test it to see if it does what we expect. With software-generated proofs, not so much, since the program IS the test.

      I think computer aided logic can be useful if we just think of a proof-generating software program as a funny, mechanically verifiable sort of abstraction, but you find yourself making an argument that rests on assuming that a computer program you wrote does what you think it does then this is problematic.

  11. here y'all go again, panicking... by Fry-kun · · Score: 3, Insightful

    To the opponents of computer-aided proof (with their hard-to-check argument), I would say this:
    It's easy to check a proof. It's hard to come up with a proof. Computers are great at checking proofs - all the program needs to do is verify whether the steps are logically correct or there's a discrepancy. Coming up with a proof, on the other hand, is a very hard task (being NP-complete, unless defined in a certain way) and thus usually requires a human (or sometimes, a lot of humans) to work on the problem.
    A computer would not be able to come up with new principles of mathematics in order to tackle a given problem, it would only try to use every trick that has been discovered to the point of creation of the program (of course that doesn't have to be the case, but my point is that human intervention would be required to "teach" the computer about the new concept so that it would try to use it for the proof)
    That is not to say that computers are useless in proofs. Obviously, they're often used as assistants in proving something-or-other, but there's also a direction in computer science where your computer would take a program that you wrote in a certain manner, and prove certain properties about it, e.g. that it is not possible to get out of array bounds in your C program...
    *yawn*
    time to sleep

    --
    Did you know that "FTW" ("for the win") is a direct translation of "Sieg Heil"?
  12. Re:Consider the source by sien · · Score: 4, Insightful
    Umm. So does this mean right wingers can't do maths?

    Secondly, the claim that a magazine that opposes the death penalty and supports gay marriage is right-wing rag (which presumably you meant in US terms, is kinda amusing.

    The Economist, correctly stated, is a liberal magazine. It supports liberal economics and liberal social policy. Unfortunately the word 'liberal' in the US has been badly distorted.

  13. Re:Science by AI by rookworm · · Score: 5, Insightful

    I concur. Math will always be about insight. The best math is simple and shows why the result is true. Most mathemeticians are unsatisfied by the four-colour proof because it does not satisfy these two conditions. Even if computers are eventually able to discover such proofs, mathematicians will still have to ask the computers to search for them. We must remember that problems like solving certain differential equations used to be difficult and involved, but now thanks to computers, we don't have to worry about them as much. The same will apply for very specialized results. The big theorems will still be up to humans to prove. Think of computer- assisted math as a kind of spellchecker or Googe suggest. Computers replacing mathematicians completely is about as far-off as computers replacing poets or historians.

    --
    The toad can't burp - and for some reason can't fart either, so it swells up and eventually explodes. --Anonymous Coward
  14. Re:The best math is always elegant. by PaschalNee · · Score: 4, Insightful
    For every complex problem there is an answer that is clear, simple, and wrong. H. L. Mencken
  15. what about the software by joss · · Score: 3, Insightful

    First off, Moore's law may not hold out for another 30 years, let alone 60.

    Secondly, how fast does software progress ? Suppose we all had computers 60 billion times faster than we do now. What would we do with them ? run SWING based java applications with tolerable responsiveness, play solitaire faster, run doom 5... [although the frame rate might be a bit low] ok... great,

    Intelligence and computing power are orthogonal concepts: suppose you communicated with aliens who were a 100 light years away, would they be less intelligent because it too 200 years to get an answer. Anything you can do on todays supercomputers, you can do on pocket calculator [with enought memory].. it just takes longer.

    Lastly, in the long run, computers wont outgrow our brains, they will be integrated with our brains.

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    http://rareformnewmedia.com/
  16. Re:Science by AI by mdwh2 · · Score: 3, Insightful

    It has been PROVEN (and it's a well-known fact) that it's impossible to create a Turing machine which will determine if a given expression is true or false

    Surely you mean it's impossible to create a turing machine that will determine if all expressions are true or false - ie, that there will always exist an expression that cannot be proved or disproved? I don't see how this prevents a computer proving or disproving a statement where such a proof exists.

    Also I don't see how a turing machine is different to a human. We can't prove whether the continuum hypothesis is true or not in ZFC, that doesn't mean that we can't prove things at all.

  17. Metaphor by Lifewish · · Score: 4, Insightful

    As a maths degree student I can confirm that a very large portion of mathematics is devoted to finding new metaphors and angles of attack for a given situation.

    This takes a ridiculous amount of pattern recognition skill (which is one area where computers tend to be outperformed by all comers) and the ability to find new ways to abstract data. A computer could possibly come up with an idea like more-than-3-dimensional space on its own, but I'd be very surprised if even the best one could think of something like topology or tensors on its own.

    Production of unusual metaphors for things we thought we knew is a major driving force for the most important mathematical developments. It's not something I can see computers managing at any time in the near future.

    --
    For the love of God, please learn to spell "ridiculous"!!!
  18. Re:Science by AI by tgibbs · · Score: 4, Insightful

    It has been PROVEN (and it's a well-known fact) that it's impossible to create a Turing machine which will determine if a given expression is true or false (see Incompleteness theorem [wikipedia.org] for details).

    This actually is more about the limitations of logic than the limitations of computers. Indeed, Godel's Incompleteness Theorem has nothing to do with computers--it is a proof that in any system of logic (that meets some very broad criteria) there must exist statements that are true but that cannot be derived from the postulates of the system by any sequence of logical steps. Adding additional axioms does not solve this; there always remain unprovable propositions. This limitation applies to proofs by humans as well as proofs computers. However, the fact that there are some theorems that cannot be proved does not mean that there are not many others that can be.

    However, the fact that there are some truths that are literally inaccessible from the postulates certainly suggests that there may be others that are accessible only by a very large number of steps, effectively requiring computers. I wonder if anybody has ever attempted to prove this?