Philip Goetz <[EMAIL PROTECTED]> wrote: >The use of predicates for representation, and the use of logic for >reasoning, are separate issues. I think it's pretty clear that >English sentences translate neatly into predicate logic statements, >and that such a transformation is likely a useful first step for any >sentence-understanding process.
I don't think it is clear at all. Try translating some poetry. Even for sentences that do have a clear representation in first order logic, the translation from English is not straightforward at all. It is an unsolved problem. I also dispute that it is even useful for sentence understanding. Google understands simple questions, and its model is just a bag of words. Attempts to apply parsing or reasoning to information retrieval have generally been a failure. It would help to define what "sentence-understanding" means. I say a computer "understands" English if it can correctly assign probabilities to long strings, where "correct" means ranked in the same order as judged by humans. So a program that recognizes the error in the string "the cat caught a moose" could be said to understand English. Thus, the grammar checker in Microsoft Word would have more understanding of a text document than a simple spell checker, but less understanding than most humans. Maybe you have a different definition. A reasonable definition for AI should be close to the conventional meaning and also be testable without making any assumption about the internals of the machine. Now it seems to me that you need to understand sentences before you can translate them into FOL, not the other way around. Before you can translate to FOL you have to parse the sentence, and before you can parse it you have to understand it, e.g. I ate pizza with pepperoni. I ate pizza with a fork. Using my definition of understanding, you have to recognize that "ate with a fork" and "pizza with pepperoni" rank higher than "ate with pepperoni" and "pizza with a fork". A parser needs to know millions of rules like this. -- Matt Mahoney, [EMAIL PROTECTED] ----- Original Message ---- From: Philip Goetz <[EMAIL PROTECTED]> To: agi@v2.listbox.com Sent: Tuesday, November 28, 2006 2:47:41 PM Subject: Re: [agi] Understanding Natural Language On 11/24/06, J. Storrs Hall, PhD. <[EMAIL PROTECTED]> wrote: > On Friday 24 November 2006 06:03, YKY (Yan King Yin) wrote: > > You talked mainly about how sentences require vast amounts of external > > knowledge to interpret, but it does not imply that those sentences cannot > > be represented in (predicate) logical form. > > Substitute "bit string" for "predicate logic" and you'll have a sentence that > is just as true and not a lot less useful. > > > I think there should be a > > working memory in which sentences under attention would "bring up" other > > sentences by association. For example if "a person is being kicked" is in > > working memory, that fact would bring up other facts such as "being kicked > > causes a person to feel pain and possibly to get angry", etc. All this is > > orthogonal to *how* the facts are represented. > > Oh, I think the representation is quite important. In particular, logic lets > you in for gazillions of inferences that are totally inapropos and no good > way to say which is better. Logic also has the enormous disadvantage that you > tend to have frozen the terms and levels of abstraction. Actual word meanings > are a lot more plastic, and I'd bet internal representations are damn near > fluid. The use of predicates for representation, and the use of logic for reasoning, are separate issues. I think it's pretty clear that English sentences translate neatly into predicate logic statements, and that such a transformation is likely a useful first step for any sentence-understanding process. Whether those predicates are then used to draw conclusions according to a standard logic system, or are used as inputs to a completely different process, is a different matter. > The open questions are representation -- I'm leaning towards CSG in Hilbert > spaces at the moment, but that may be too computationally demanding -- and > how to form abstractions. Does CSG = context-sensitive grammar in this case? How would you use Hilbert spaces? ----- This list is sponsored by AGIRI: http://www.agiri.org/email To unsubscribe or change your options, please go to: http://v2.listbox.com/member/?list_id=303 ----- This list is sponsored by AGIRI: http://www.agiri.org/email To unsubscribe or change your options, please go to: http://v2.listbox.com/member/?list_id=303
