[ont.events] UW CS Colloq. Dr. Hirst on "Semantic Interpretation Against Ambiguity."

mwang@watmath.UUCP (mwang) (05/30/84)

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                           -  Wednesday, June 6, 1984.

Dr. G. Hirst of the University of Toronto will speak on
``Semantic Interpretation Against Ambiguity.''

TIME:                3:30 PM

ROOM:              MC 5158

ABSTRACT

We describe a new approach to  semantic  interpretation
in  natural  language understanding, and mechanisms for
both lexical and structural disambiguation that work in
concert with the semantic interpreter.

Traditionally, translation from the  parse  tree  of  a
sentence  to  a semantic representation (such as frames
or procedural semantics) has always been  the  most  ad
hoc  part  of  natural  language understanding systems.
However, recent advances in linguistics,  most  notably
the system of formal semantics known as Montague seman-
tics, suggest ways of putting  semantic  interpretation
onto a cleaner and firmer foundation.

Absity, the system we describe, is a  Montague-inspired
semantic  interpreter.   Like  Montague formalisms, our
semantics is compositional by design  and  is  strongly
typed, with semantic rules in one-to-one correspondence
with the meaning-affecting rules of  a  Marcus  parser.
We have replaced the Montague semantic objects -- func-
tors and truth conditions -- with elements of the frame
language  Frail.   Absity's  partial results are always
well-formed Frail objects.

A semantic interpreter must be able to provide feedback
to the parser to help it handle structural ambiguities.
In Absity, this  is  done  by  the  ``Semantic  Enquiry
Desk,''  a  process that answers the parser's questions
on semantic preferences.  Disambiguation of word senses
and  of  case slots is done by a set of procedures, one
per word or slot, each of which determines its  correct
sense  in  cooperation  with  the  others.  A partially
disambiguated procedure's remaining  possibilities  are
well-formed  Frail objects that can be seen and used by

                     May 30, 1984

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other processes, including the Semantic  Enquiry  Desk,
just as a person can see many of the details of a part-
ly developed ``instant'' photograph.

It is from the fact that  partial  results  are  always
well-formed semantic objects that the system gains much
of its power.  This, in turn,  comes  from  the  strict
correspondence  between syntax and semantics in Absity.
The result is a foundation for semantic  interpretation
that we believe to be superior to previous approaches.

Coffee and refreshments will be served at 3:00 PM.

                     May 30, 1984