representation of input text in a conversation

[Bruno Emond]

I have been working on modelling natural language processing with
ACT-R for some time now.  I am working on a paper (long overdue,
thanks...) that would present some ideas that are included here.
I am not familliar with NL-Soar but the question of parsing and
semantic interpretation seems to go along the lines where a chunk
holds various types of information such as the string time postion
(thanks to Christian who sent his e-mail while I am writing
this one...), the syntactic category, and the semantic interpretation.

The following reflexions are probably going to be more relevant to
human than to orangutan language processing (sorry Jim, although
it might be helpful).  I work within the framework of categorical
grammar which classifies syntactic categories as basic or functional.

=46or eamaple, An intransitive verb would be of the type NP\S which is a fun=
ction
that takes an adjacent NP to its left to produce an S.  Basically,
in a simple categorical grammar there are only two grammar rules
(left and right application). These rules combine adjacent syntactic
categories. The interest in categorical grammar is that there is a direct
mapping between the syntactic and semantic functions based on lambda
conversion.  A possible implementation of a left application rule
would have the following representation, where begin and end are
integers representing the temporal position of the a string, category
argument, result are syntactic labels, the meaning of the parse-chunk
and a lambda-operator to indicate which slot sould be filled with the
semantic argument.

(p left-application.slot1
   =3Dparse-chunk-under-focus>
   isa             parse-chunk
   begin-string    =3Dmiddle
   end-string      =3Dend
   operator        left
   argument        =3Dargument
   result          =3Dresult
   meaning         =3Df-expression
   lambda-operator slot1

   =3Dadjacent-parse-chunk>
   isa             parse-chunk
   begin-string    =3Dbegin
   end-string      (!eval! (- =3Dmiddle 1))
   category        =3Dargument
   meaning         =3Da-expression

   =3D=3D>

   =3Df-expression>
   isa             semantic-expression
   slot1           =3Da-expression

   =3Dnew-parse-chunk>
   isa             parse-chunk
   begin-string    =3Dbegin
   end-string      =3Dend
   category        =3Dresult
   meaning         =3Df-expression

   !focus-on!      =3Dnew-parse-chunk
)


There are multiple possible versions of this type of production.  This
version has a relative shallow goal structure because the semantic
interpretation or a new new goal to create the new parse-chunk
are not pushed.  This question of shallow goal structure seems to me to
be an important issue in modelling natural language processing because
the whole process has to be quick.  In the case of the left application
rule, note that there has to be another production called to expand the
value of result in case it is a functional category.  All this takes time.
One could think of a two chunks retrieval condition but it would fail
in case of a non functional category.

Another problem is to limit as much as possible productions that fail
which also increase the overall processing time. For example, there is
no empirical evidence, to my knowledge, that it takes more time to parse
a sentence if its subject is a proper noun or a complete np. It
seems reasonable on linguistic and performance grounds to distinguish
these two basic categories as well as considering the proper noun as a
subtype of noun phrase.  It seems also reasonable to assume that there
is only one category for an intransitive verb (takes an np a left adjacent
category to produce a sentence).  Although one could assume two lexical
entries the retrieval of which would depend on the actual syntactic
category just processed.

Bruno.



***********************************************
Bruno Emond, Ph.D.
bruno_emond at uqah.uquebec.ca
Tel.:(819) 595-3900  1-4408
T=E9l=E9copieur: (819) 595-4459
- D=E9partement des Sciences de l'=C9ducation,
  Professeur Agr=E9g=E9
  Universit=E9 du Qu=E9bec =E0 Hull.
  Case Postale 1250 succursale "B",
  Hull (Qu=E9bec), Canada. J8X 3X7
- Institute of Interdisciplinary Studies:
  Cognitive Science.
  Adjunct Research Professor
  Carleton University
***********************************************