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Re: about Coolness, Impatience and Complexity

by Abigail (Deacon)
on Jul 14, 2001 at 03:54 UTC ( #96630=note: print w/ replies, xml ) Need Help??

in reply to Re: Re: about Coolness, Impatience and Complexity
in thread about Coolness, Impatience and Complexity

We have a well developed theory that tells us what computations can and can't be done by a Turing machine with a finite length of tape.
Please stick to the subject. The subject isn't computability, a domain in which Turing Machines frequent, but run time complexity of algorithms, of which you claimed where measured how fast they can be done on Turing Machines - but then you later claimed that any device that couldn't be build was irrelevant. But yeah, we could build a machine with a finite tape. Now, how many of them do you have laying around?

But computer science is about computing, and things that compute are computers, by definition.
Not everything that is about computing needs to be done by a "thing"! Are you dismissing the majority of physics as well because the models they use don't exist in the real world? It's Computer SCIENCE not electronics.
And what is computing? Pushing information around. The flow of information is governed by information theory, which tells us that information is very nearly a physical thing. We usually deal with information in the form of bits, but it doesn't have to be stored that way. A given quantity of information is going to take up a finite minimum amount of time and space, no matter what you do with it. Getting as close as possible to the minimum is an engineering problem that we'll be workng on forever. But it's important to keep in mind that we're dealing with stuff that's not infinitely compressible. Information is solid.
So what? Pushing bits around is indeed an engineering problem. Just like getting measurements of stars, nebulae and planets is an engineering problem, and has nothing to do with astronomy. Computer Science isn't about how to move bits around - Computer Science is about where to move "the bits" to. And note that I'm using quotes here, because Computer Science doesn't necessary deal with physical bits. It all depends on your computational model what your basic units are.

I don't think there's as much distinction as you think between "computer science" and "computing science".
I'm sorry, but did I say there was any difference? I don't think so. All I said was that some people think it's a better description of the same thing.

Before, I said, "why talk about computers that can't possibly be built?" Now, I say, "why talk about computations that can't possibly be performed?
Sir, you have never been a scientist, you are not a scientist, and you never will be a scientist. You just don't get it. If people always would have had that attitude, we would still live in the stone age.

-- Abigail

Comment on Re: about Coolness, Impatience and Complexity
Re: Re: about Coolness, Impatience and Complexity
by no_slogan (Chaplain) on Jul 14, 2001 at 04:39 UTC
    I have only a few things left to say, and then you may have the last word.
    • My mention of Turing machines was ill-considered, as I have already admitted
    • Turing machines are interesting because:
      • They are powerful enough to be widely applicable
      • They are simple and easy to think about
      • They are not very much different from a machine that could actually be constructed
    • Computability and complexity of algorithms are inextricably connected
    • Any reasonably competent programmer can code a finite tape Turing machine in a matter of minutes
    • Anticipitating your probable response to the above, imagine that I hand you a black box which I claim contains a Turing machine. Without opening the box, what kind of "Turing test" would you put it through to determine whether it contains a "real" Turing machine or a simulation of one using a general-purpose computer?

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