Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!know!sdd.hp.com!usc!julius.cs.uiuc.edu!ux1.cso.uiuc.edu!bach.cogsci.uiuc.edu!morgan From: morgan@bach.cogsci.uiuc.edu (Jerry Morgan) Newsgroups: comp.lang.prolog Subject: Re: Question about DCGs and natural language grammars Message-ID: <1990Nov21.164942.7157@ux1.cso.uiuc.edu> Date: 21 Nov 90 16:49:42 GMT References: Sender: news@ux1.cso.uiuc.edu (News) Distribution: comp Organization: University of Illinois at Urbana Lines: 29 mark@adler.philosophie.uni-stuttgart.de (Mark Johnson) writes: >What's worrying me is this: if we use a DCG grammar to >define a relation means/2 true of a string of English words >and some representation of its meaning (say, an encoding of >a first-order formula), we can prove things like the >following: > S=[i,saw,a,man,with,a,telescope], means(S,M1), means(S,M2). >where M1 represents a meaning where where the man has a telescope, >and M2 represents a meaning where the seeing is done with the >telescope. >That is, from our axioms we can prove that S means M1 *and* S means M2. >The problem is that in the real world it *doesn't*: the English sentence >S means M1 *or* M2. It seems to me the DCG system has got the facts right: it's true that S means M1, and it's true that S means M2. What's missing is the distinction between sentence and use of a sentence. Even though (S means M1 and S means M2), on any particular occasion of use where S is uttered by A, it's not true that (A means-to-convey M1 AND A means-to-convey M2); rather, (A means-to-convey M1 OR A m-to-c M2). So you need some way of distinguishing sentence type and sentence token.