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Newsletter Dec 20, No. 9


                       C S L I   N E W S L E T T E R
___________________________________________________________________________
December 20, 1984               Stanford                      Vol. 2, No. 9
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         A weekly publication of The Center for the Study of Language and 
	 Information, Ventura Hall, Stanford University, Stanford, CA 94305
                           ____________ 


        *****THURSDAY CSLI ACTIVITIES BETWEEN QUARTERS***** 
There will be no center-wide activites today, December 27, or
January 3.  Regular Thursday activities will resume on January 10.
A New Year's message from Jon Barwise appears on page 2.
			    ______________

                SUMMARY OF NOVEMBER 21 AREA C MEETING

Topic:     REVE: A system for solving problems in equational theories,
              based on term rewriting techniques
Speaker:   Jean-Pierre Jouannaud, Professor at University of NANCY, FRANCE,
              on leave at SRI-International and CSLI.

Equational Logic has been adopted by mathematicians for a very long
time and by computer scientists recently.  Specifications in OBJ2, an
``object-oriented'' language designed and implemented at
SRI-International, uses equations to express relations between
objects.  To express computations in this logic, equations are used
one way, e.g. as rules.  To make proofs with rules in this logic
requires the so-called ``confluence'' property, which expresses that
the result of a computation is unique, no matter the order the rules
are applied.  Proofs and computations are therefore integrated in a
very simple framework.  When a set of rules does not have the
confluence property, it is augmented by new rules, using the so-called
Knuth and Bendix completion algorithm, until the property becomes
satisfied.  This algorithm requires the set of rules to have the
termination property, i.e., an expression cannot be rewritten forever.
It has been proved that this algorithm allows one to perform as
inductive proof without invoking explicitly an induction principle and
to solve equations (unification) in the corresponding equational
theory as well.
			_____________

	    LAST '84 NEWSLETTER AND NEW '85 EDITOR

The present issue of the Newsletter is the last of this year's. The next
issue will appear on January 3, 1985. Beginning with that issue, the
Newsletter will be edited by Emma Pease (Emma at SU-CSLI).
	                Happy Holidays
     			_____________

	                 CSLI REPORTS

``Moving the Semantic Fulcrum'' by Terry Winograd (Report No. CSLI--84-17)
has just been published. Report No. CSLI--84-2, ``The Situation in
Logic--I'' by Jon Barwise, which has been out of print, is now available.
To obtain a copy of these reports write to Dikran Karagueuzian, CSLI,
Ventura Hall, Stanford 94305 or send net mail to Dikran at SU-CSLI.

Page 2                   CSLI Newsletter                   December 20, 1984
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		NEW YEAR'S MESSAGE FROM JON BARWISE

Dear CSLI Folks,

This is the last Newsletter of 1984, and a time for recalling just how
much has been accomplished this year.  Recent conversations I have had
with visitors from around the world make me realize that CSLI is far
different than it was this time last year.  It is now a real place,
one with a reputation, a history, a subject matter, a first-rate
computational environment, and, most important, a real sense of
community.  Area NL is still going strong, and areas F and C have now
come into their own, making a real impact on the research lives of
those involved.  In addition, the new area P is getting organized and
shows real promise of adding to our understanding of language and
information.  Only the dedication of many CSLI Folk has made all this
possible, the dedication that shows up in the day-to-day work of the
staff, in preparing talks for seminars, in committee meetings and
report writing, in organizing workshops, and all the other tasks that
go into making a research center work.  Thanks to all of you!
However, we have not done this alone.  We have had an enormous amount
of support from many others: from Charles Smith, Dr. Carl York and the
Board and staff of SDF, from officials at SRI, Stanford, and Xerox
PARC, Bell Labs, from our Advisory Panel, and from a host of visitors
who have greatly enriched the intellectual life of the Center.  Thanks
to all of them, too!  This past year has been a good one for me, my
family, and for CSLI.  I hope it has been a good one for each of you,
and that next year will be even better.
							Happy New Year,
							Jon Barwise
		            _____________
		
                     SUMMARY OF NOVEMBER 28 AREA C
        ROUND TABLE DISCUSSION OF FUNCTIONAL AND LOGIC PROGRAMMING

Functional and Logic Programming are two of the most exciting and active
developments in contemporary computer science.  Functional Programming is
concerned with the elimination, or at least the taming, of so-called
side-effects.  Logic Programming is concerned with having languages that
are closer to some form of pure logic (although some people use the phrase
to refer only to Prolog). Below are summaries of some of the participants'
presentations.

Kokichi Futatsugi -- indicated why the Japanese Fifth Generation Project has
    chosen logic programming as its basis.
Jose Meseguer -- discussed some of the principles of two logic and functional
    programming languages being developed at CSLI, OBJ2 and Eqlog.
Jean-Pierre Jouannaud -- discussed why theorem proving can be expected
    to be more effective and useful for functional and logic
    programming languages.
Joseph Goguen -- suggested why logic and functional programming
    languages may be highly appropriate for research in natural
    language syntax and semantics.
Yoni Malachi -- described Tablog and the way it uses nonclausal resolution
    equality rewriting to support a more expressive language.
Masahiko Sato -- discussed why unification enables natural
    ``unification'' of logic and functional programming languages.
Brian Smith -- indicated (at least one person's view of) what would be
    required of a functional/logical programming language in order to
    make it appropriate for models of human reasoning.
Fernando Pereira -- gave a user's perspective of what is wrong (and
    some of what is right!) with Prolog and what he expects from
    functional programming models; will also remark on some
    non-problems and non-solutions that keep being reinvented.

CORRECTION: In last week's Newsletter the title ``SUMMARY OF LAST
  WEEK'S NL1 SEMINAR'' on page 2 should have read ``SUMMARY OF LAST
  WEEK'S NL4 SEMINAR.'' Our apologies for the error.
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