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Re: The (futile?) quest for an automatic paraphrase engine

by BrowserUk (Patriarch)
on May 17, 2004 at 05:02 UTC ( [id://353869]=note: print w/replies, xml ) Need Help??


in reply to The (futile?) quest for an automatic paraphrase engine

How long do you have to achieve your goal?

Given that you (or your friend) are intending to have a human being make final arbitration, you have reduced the problem from one of almost impossible to just very, very hard--but don't let that stop you from trying, if you have the time.

Whenever you see discussion about natural language programming, the cliched example of "time flies like an arrow" comes up, but why? What is special about that phrase?

My conclusion (and I'm no linguist as anyone who has read any of my posts will tell you:), is that what is special about that phrase is it doesn't make any sense!

The challenge of the phrase is supposed to be how would any NLP or AI system be able to make sense of it. The answer is "It can't", but then, neither can a human being.

Time flies like an arrow.

Time isn't solid, so how can it fly?

Ah, but it's an analogy. "Time flies", means it passes very quickly.

Hang on. Time passes at a constant rate (Einstein aside), and "quickly" is an informal measure of time. So, How can you measure time in terms of time? Time cannot go quickly nor slowly. It just passes.

But it's not a literal description of how time passes, it's a subjective description. Sometimes, human beings perceive time to pass more slowly or more quickly than at other times.

Oh, I see. So arrow move quickly, therefore "time flies like an arrow" means that time is perceived to be moving more quickly than... well, when it isn't flying like an arrow?

But an arrow, leaves the string of say a 70# bow travelling at around 300 ft/sec--that's 200 mph, which is pretty quick relatively--but from that point on it starts to slow down, until it stops!

So, given that top end sports cars, motorcycles and trains can achieve and sustain 200 mph, an arrow is a pretty piss poor analogy for something travelling quickly.

Maybe the point it that an arrow goes from A to B and doesn't come back? Unless someone picks it up and fire it back of course. And the analogy is meant to relate to that. Time only travels one way (sci-fi not withstanding:).

But hang on, if I launch an arrow straight up, then it comes back down. If there's no wind, and the drag from the flights is even, and I manage to launch it exactly vertically, it might even end up back where it started from...or worse.

Hmmm. Write an AI/NLP program that can divine the meaning of the phrase "Time flies like an arrow".

while( <DATA> ) { m[time flies like an arrow]i and print( "Does not compute!" ) and next; ## Some other stuff goes here. }

There you go:)


Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail

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Re: Re: The (futile?) quest for an automatic paraphrase engine
by kiat (Vicar) on May 17, 2004 at 05:26 UTC
    My understanding of "Time flies like an arrow"...

    I think someone (could be Chomksy) paired that sentence with "Fruit flies like a banana."

    I may be wrong but I think "Fruit flies like a banana" is used to demonstrate the difficulty of understanding the meaning of a given utterance. So "Fruit flies like a banana" can be understood as:

    1) A type of insects called fruit flies that like a banana (so 'like' is used a a verb)

    2) A kind of fruit that flies like a banana. ('flies' used a verb and 'like' as a conjunction)

    Incidentally, I found some articles here:

    http://www.fact-index.com/n/na/natural_language_understanding.html

      First, my post was intended to be (semi) humerous. That said, I'll continue my tirade a little further.

      I understand what the phrase and the pairing of the two phrases is meant to demonstrate. However, I would have to say that I think that understanding is derived and consequently artificial.

      Take the second phrase. "Fruit flies like a banana" and your two interpretations of it.

      1. A type of insects called fruit flies that like a banana (so 'like' is used a a verb).

        Can you really relate to anyone actually using that phrase to achieve that meaning?

        I know we might say that "People like a drink", where the singular usage "a drink" does not imply that they only like one, but "Fruit flies like a banana"?

        They might say "Fruit flies like bananas".

      2. A kind of fruit that flies like a banana. ('flies' used a verb and 'like' as a conjunction).

        Hmm. A banana is fruit. Soooo, fruit flies like fruit?

        But fruit doesn't fly. It falls. I can be thrown. And if you put it on an aeroplane, it can be flown somewhere.

        I seriously doubt that either an ornithologist or an aerospace engineer would recognise any of those situations as being "flight".

        About the best interpretation of "Fruit flies like a banana", related to flight, that I can come up with is that:

        Like bananas, fruit doesn't fly.

        Something along the lines of "Flies like a lead ballon", but if that's the meaning that is being conveyed, then the latter is a much better way of conveying it.

      I guess the point I am making is that both phrases are tortuously derived to make the point that natural language processing is hard--but neither are exactly "natural language".

      It's a bit like saying that you cannot make a return trip to the Sun, so therefore space travel, whilst not impossible, is totally unworthwhile. Or building a bridge across the Atlantic is practically impossible, therefore building bridges is a waste of time.

      If you set the goals (for anything) artificially high, then you can render the problem insoluble.

      There are many problems that are generically insoluble in practical time frames, but that doesn't prevent partial solutions to subsets of the generic problem being used every day to good effect.


      Examine what is said, not who speaks.
      "Efficiency is intelligent laziness." -David Dunham
      "Think for yourself!" - Abigail

        Not surprisingly the number one result on a Google search for Fruit flies like a banana is an essay on Writing Unambiguously :)

        The article is worth reading for itself BTW

        --
        Do not seek to follow in the footsteps of the wise. Seek what they sought. -Basho

        I may be wrong with the two interpretations there. Here is a better example at illustrating the fact that a perfectly grammatical sentence can be ambiguous:

        A) John saw the man with a telescope.

        The sentence can be interpreted as:

        1) With the help of a telescope, John saw the man.

        2) John saw the man who had a telescope with him.

        Another example:

        B) Visiting relatives can be a nuisance.

        (B) can be understood as:

        3) The act of visiting people can be a nuisance.

        4) Relatives who visit us can be a nuisance.

        There are some things which computers can't do too well because they are missing a human understanding of context and how the world works. Since computers tend to rely on syntax to "understand" language, but don't have any concept of what would be the most "logical" interpretation of a given sentence, they tend to fail at this point. I guess my point is that you need some knowledge about the world to be able to intelligently disambiguate synactically ambiguous sentences. What most linguistic researchers have done up to now is use a hand-tagged training corpus to disambiguate and give filter out unlikely (atypical) interpretations of a syntactic structure.

        The idea of dealing with typical cases is basically what you're suggesting here, I think.

        --
        Damon Allen Davison
        http://www.allolex.net

      Remember...?
      "The boat floated down the river sank".
      "Oysters oysters split split"
      Jeez, no wonder half of the class went mad on Semantics and Syntax 101.

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