erhoogerbeet@watmath.UUCP (05/23/87)
Hello. I am an undergrad going into computer science, and have long been interested in ai. But ai has always been "above" us lowly first and second year students and we have been relegated to the quicksorts and recursive n factorial problems. I think this would be a good place to have articles that introduced the laymen to ai to keep our interest. Recently, we worked on a simple compiler for numerical expressions using pwap on cms which is similar to yacc on unix. We entered a modified Backus-Naur Form and it spewed forth source code in pascal for an expression interpreter. Also, I have played many an adventure game and have always been intrigued by the way it parses and interprets commands given to it in simple English. Is there a Backus-Naur Form for the English language itself or is this too complicated? If not, how is it that we can understand a huge variety of different sentence forms and still recognize that some are syntactically incorrect? Basically, what I am asking is it possible to do syntactic checking as if "compiling" a sentence with rules set down in some BNF? As I understand it so far, natural language processing would have at least two levels (syntactic, semantic) and that syntactic checking level would be the basis of the other. "I bed he not on." is not syntactically or semantically correct. "Colourless green ideas sleep furiously." syntactically but not semantically correct. To be semantically correct, a sentence must be syntactically correct. Semantic checking would involve some connotation checking using trees and associations, but there is probably no clear-cut way of doing this. So I ask about syntactic checking. Some compilers have a front-end/back-end structure. Could syntactic checking be a front end part of the compiler? Theoretically, a syntax checker could be given a certain BNF for a language and be plugged into a back end semantic checker. But there must be someone out there on the net who can set me straight and do it in layman's terms. From an interested undergrad: ------ --------- ------------------------------------------ erhoogerbeet@watmath.uucp "`The Guide says there is an art to flying,' ehoogerbeets@wateuler.uucp said Ford,`or at least a knack. The knack lies Edwin (Deepthot) in learning how to throw yourself at the ground Hoogerbeets and miss.' He smiled weakly."
edusoft@ecf.UUCP (05/27/87)
In article <13263@watmath.UUCP> erhoogerbeet@watmath.UUCP (Edwin (Deepthot)) writes: >Is there a Backus-Naur Form for the English language itself or is this too >complicated? If not, how is it that we can understand a huge variety of >different sentence forms and still recognize that some are syntactically >incorrect? Basically, what I am asking is it possible to do syntactic >checking as if "compiling" a sentence with rules set down in some BNF? The most easily locatable reference I know of for a phrase-structure (you'll have to convert to BNF) grammar of English is: Generalized Phrase Structure Grammar Gerald Gazdar, Ewen Klein, Geoffrey Pullum and Ivan Sag 1985 Blackwell and Harvard University Press Mind you, that'll be quite a task, as GPSG abstracts away from atomic node labels and order in constituents. You'd probably have to write a GPSG to BNF compiler. >To be semantically correct, a sentence must be syntactically correct. A lot of people would agree with this statement, but this does not allow for partial interpretation of sentences. It is also possible to interpret syntactically incorrect sentences, such as: Me went to the store. >But there must be someone out there on the net who can set me straight and >do it in layman's terms. I have my doubts whether anything in linguistics can be explained in layman's terms. bill idsardi computational linguist educational software products 1263 bay st. toronto, ontario canada M5R 2C1 922-0087 ...utzoo!utai!utecfa!edusoft
mj@elmgate.UUCP (05/30/87)
I recently finished an experimental graduate course in
Natural Language Processing at Purdue, where I am working on
my MSEE. It was offered for graduate credit jointly by
the schools of Electrical Engineering and English, and co-taught
by an EE and a linguistics professor. Due to
other time constraints, I did not complete the final project,
but understood the material well enough to have done so if
I'd not been so rushed. The course used Terry Winograd's
LANGUAGE AS A COGNITIVE PROCESS: VOLUME I: SYNTAX, which
discusses context-free phrase-structure grammars,
active chart parsing, transformational grammars, and
describes recursive and augmented transition networks (RTN's
and ATN's) well enough that implementation is
really not too difficult. One of the nice things about the ATN
parser is that (for the language described by the ATN), it can
be written to produce a recursive data structure that describes
all of the possible meanings of a sentence available to the ATN.
This means that, with a carefully described grammar and for a
particular subset of a language, syntactically unambiguous
sentences will produce a unique parse, and ambiguous sentences
("Time flies like an arrow") will produce multiple parses.
Semantic analyzes specially designed for acting on the frames
produced by the ATN parser can then choose an appropriate parse,
ask for clarification, update knowledge bases, etc.
I can give a limited recommendation for Winograd's book: it is fairly
understandable, but it was quite hard to find anyone who
liked his algorithm notation. Winograd introduces an algorithm
description language called "DL", and I can't say I like it much.
It does have the advantage of separating the topic from the
technology, i.e., you don't have to know any particular programming
language to understand the algorithms. Ain't my cup 'o' tea, tho'.
One of the posters mentioned "waiting FOREVER for Volume II"
of Winograd's book to come out. Don't hold your breath. I
think I'll get the final volume (9 is it?) of THE ART
OF COMPUTER PROGRAMMING before I buy Winograd Vol II. I could be
wrong, though, and would love to see Vol II in print.
-------------------------------------------------------------------------------
Mark A Johnson - Eastman Kodak Co. - Dept 646 - KEEPS - Rochester, NY 14650
The opinions expressed above are not necessarily those of Eastman Kodak Company
and are entirely my responsibility.edwards@uwmacc.UUCP (mark edwards) (06/01/87)
In article <639@elmgate.UUCP> mj@elmgate.UUCP (Mark A. Johnson) writes:
:
: One of the nice things about the ATN
: parser is that (for the language described by the ATN), it can
: be written to produce a recursive data structure that describes
: all of the possible meanings of a sentence available to the ATN.
: This means that, with a carefully described grammar and for a
: particular subset of a language, syntactically unambiguous
: sentences will produce a unique parse, and ambiguous sentences
: ("Time flies like an arrow") will produce multiple parses.
: Semantic analyzes specially designed for acting on the frames
: produced by the ATN parser can then choose an appropriate parse,
: ask for clarification, update knowledge bases, etc.
An ATN must be intuitively pleasing for an MSEE. And for a simple
sentence like "Time flies like an arrow", it is easy enough for
the parser to parse. There are not many permutation for a string
of five words. (Of course for langauges like japanese with a lot
of homonyms, it could be much harder). As sentences get longer,
and gapping and deletion start to happen, the inappropriateness
of recursive structures bog down the processing.
mark
--
edwards@unix.macc.wisc.edu
{allegra, ihnp4, seismo}!uwvax!uwmacc!edwards
UW-Madison, 1210 West Dayton St., Madison WI 53706jcz@sas.UUCP (John Carl Zeigler) (06/01/87)
It is not be necessary, nor sumptimes suffic'nt, foah an Englizt sentence to simptatically correct in oder to habe semantic content. A'int Broca's area wunnerful? -- --jcz John Carl Zeigler SAS Institute Inc. Cary, NC 27511 (919) 467-8000 ...!mcnc!rti-sel!sas!jcz
erhoogerbeet@watmath.UUCP (06/03/87)
In article <242@sas.UUCP> jcz@sas.UUCP (John Carl Zeigler) writes: >It is not be necessary, nor sumptimes suffic'nt, foah an Englizt >sentence to simptatically correct in oder to habe semantic content. >A'int Broca's area wunnerful? >--jcz >John Carl Zeigler >SAS Institute Inc. >Cary, NC 27511 (919) 467-8000 ...!mcnc!rti-sel!sas!jcz The human brain converts this into sounds or even recognizes the general shape of *known* words and infers the meaning. But given something syntactically correct, wouldn't that make life easier? Edwin (Deepthot) Hoogerbeets
gilbert@aimmi.UUCP (06/10/87)
In article <242@sas.UUCP> jcz@sas.UUCP (John Carl Zeigler) writes: >It is not be necessary, nor sumptimes suffic'nt, foah an Englizt >sentence to simptatically correct in oder to habe semantic content. >A'int Broca's area wunnerful? Zo wab? Ayn wi orl juz gezzin duh worvesunthen parsinapropa? Juzlux lijk leghziegheil suds tea tchu shone 2 mi. Sin tackssisall dill sehr wansyer dun gezzin. Ask eecummings. P.S. flames on leghziegheil to /dev/null please :-) -- Gilbert Cockton, Scottish HCI Centre, Ben Line Building, Edinburgh, EH1 1TN JANET: gilbert@uk.ac.hw.aimmi ARPA: gilbert%aimmi.hw.ac.uk@cs.ucl.ac.uk UUCP: ..!{backbone}!aimmi.hw.ac.uk!gilbert