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AIList Digest Volume 3 Issue 154
AIList Digest Thursday, 24 Oct 1985 Volume 3 : Issue 154
Today's Topics:
Seminars - Representation of Natural Forms (MIT) &
LOGIN: Logic Programming with Inheritance (UPenn) &
Database Updates in Prolog (UPenn) &
Concurrent Logic Programming (CMU) &
Person Schemata (UCB) &
NETTALK: Connectionist Speech Learning (UPenn)
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Date: Mon 21 Oct 85 09:55:17-EDT
From: "Brian C. Williams" <WILLIAMS%MIT-OZ@MIT-MC.ARPA>
Subject: Seminar - Representation of Natural Forms (MIT)
[Forwarded from the MIT bboard by SASW@MIT-MC.]
Thursday 24, October 4:00pm Room: NE43- 8th floor Playroom
The Artificial Intelligence Lab
Revolving Seminar Series
"Perceptual Organization And The Representation Of Natural Form"
Alex P. Pentland
AI Center, SRI Int'l and CSLI, Stanford
To understand both perception and commonsense reasoning we need a
representation that captures important physical regularities and that
correctly describes the people's perceptual organization of the
stimulus. Unfortunately, the current representations were originally
developed for other purposes (e.g., physics, engineering) and are
therefore often unsuitable.
We have developed a new representation and used it to make accurate
descriptions of an extensive variety of natural forms including people,
mountains, clouds and trees. The descriptions are amazingly compact.
The approach of this representation is to describe scene structure in a
manner similar to people's notion of ``a part,'' using descriptions that
reflect a possible formative history of the object, e.g., how the object
might have been constructed from lumps of clay.
For this representation to be useful it must be possible to recover such
descriptions from image data; we show that the primitive elements of
such descriptions may be recovered in an overconstrained and therefore
reliable manner. An interactive ``real-time'' 3-D graphics modeling
system based on this representation will be shown, together with short
animated sequences demonstrating the descriptive power of the
representation.
------------------------------
Date: Tue, 22 Oct 85 18:21 EDT
From: Tim Finin <Tim%upenn.csnet@CSNET-RELAY.ARPA>
Subject: Seminar - LOGIN: Logic Programming with Inheritance (UPenn)
Colloquium
3pm 10-26-85
23 Moore, University of Pennsylvania
LOGIN: A LOGIC PROGRAMMING LANGUAGE WITH BUILT-IN INHERITANCE
HASSAN AIT-KACI
A.I. Program, MCC, Austin, Texas
Since the early days of research in Automated Deduction, inheritance has been
proposed as a means to capture a special kind of information; viz., taxonomic
information. For example, when it is asserted that "whales are mammals", we
understand that whatever properties mammals possess should also hold for
whales. Naturally, this meaning of inheritance can be well captured in logic
by the semantics of logical implication. However, this is not operationally
satisfactory. Indeed, in a first-order logic deduction system realizing
inheritance as implication, inheritance from "mammal" to "whale" is achieved by
an inference step. But this special kind of information somehow does not seem
to be meant as a deduction step---thus lengthening proofs. Rather, its purpose
seems to be to accelerate, or focus, a deduction process---thus shortening
proofs.
In this talk, I shall argue that the syntax and operational interpretation of
first-order terms can be extended to accommodate for taxonomic ordering
relations between constructor symbols. As a result, I shall propose a simple
and efficient paradigm of unification which allows the separation of (multiple)
inheritance from the logical inference machinery of Prolog. This yields more
efficient computations and enhanced language expressiveness. The language thus
obtained, called LOGIN, subsumes Prolog, in the sense that conventional Prolog
programs are equally well executed by LOGIN.
I shall start with motivational examples, introducing the flavor of what I
believe to be a more expressive and efficient way of using taxonomic
information, as opposed to straight Prolog. Then, I shall give a quick formal
summary of how first-order terms may be extended to embody taxonomic
information as record-like type structures, together with an efficient type
unification algorithm. This will lead to a technical proposal for integrating
this notion of terms into the SLD-resolution mechanism of Prolog. With
examples, I shall illustrate a LOGIN interpreter.
------------------------------
Date: Tue, 22 Oct 85 11:35 EDT
From: Tim Finin <Tim%upenn.csnet@CSNET-RELAY.ARPA>
Subject: Seminar - Database Updates in Prolog (UPenn)
Colloquium - 3pm 10-24-85
216 Moore, University of Pennsylvania
A LOGICAL APPROACH TO DATABASE UPDATES IN PROLOG
DAVID S. WARREN , SUNY AT STONY BROOK
The power of the logic programming paradigm (exemplified by the Prolog
programming language) lies in its close relationship to logic. This gives
logic programs a clean, simple, and elegant declarative semantics, making them
easy to understand and reason about. It has turned out, however, that in order
to make Prolog a practical and usable programming language, several
computational (and non-logical) extensions must be added. These extensions
include the ``not'' operator, the ``setof'' operator, the ``var'' predicate,
and the ``assert'' and ``retract'' operators. To the extent that these
operators are non-logical, they destroy the declarative semantics of programs
that use them. Such a program can only be understood by knowing its
computation sequence.
Progress has been made in providing a logical semantics for the ``not''
operator in Prolog, and the circumstances under which Prolog's negation as
failure rule coincides with logical ``not'' are now reasonably well understood.
This has allowed Prolog programs which use the ``not'' operator (meeting the
appropriate constraints) to be understood declaratively.
This talk describes an approach to providing a logical semantics for the Prolog
operator ``assert''. We use a simple modal logic, which leads to a slightly
different operational semantics for ``assert'' and suggests ways that the
assert operator should be restricted in application. The resulting system has
interesting implications for a theory of database updates.
------------------------------
Date: 22 Oct 1985 1109-EDT
From: Lydia Defilippo <DEFILIPPO@C.CS.CMU.EDU>
Subject: Thesis Oral - Concurrent Logic Programming (CMU)
ABSTRACT OF THESIS PROPOSAL
Speaker: Vijay A. Saraswat
Date: Friday - 1 November, 1985
Time: 10:00 am
Place: 7220
Topic: CONCURRENT LOGIC PROGRAMMING LANGUAGES
The domain of logic programming languages, consists, of the most part,
of programming languages based on Horn logic which provide modified
forms of top-down, SLD-refutation execution engines. A program in
these languages consists of a set of definite clause axioms with
(perhaps implicit) control information for guiding the underlying
engine. Execution is initiated by the presentation of a conjunction
of goals or queries and terminates when the engine, following the
prescribed control, discovers either a proof of the goals, or the
impossibility of such a proof. Concurrent logic programming (CLP)
languages provide execution engines capable of pursuing concurrently
proofs of each of the goals in a conjunctive system (so-called
and-parallelism) and also different possible proof paths for each goal
(or-parallelism). Examples of existing concurrent Horn languages are
Concurrent Prolog, Parlog, GHC, Delta-Prolog and CP[!,|,&].
In this thesis I propose to lay a sound theoretical foundation for,
and explore the paradigm of, CLP languages. Specifically, I propose
to investigate the design, semantics, implementation and use of such
languages.
The thesis is intended to make contributions to each of the following
areas:
-- programming language design, via
-- an understanding of the design space for
concurrent programming languages based on annotated Horn logic,
-- the design of a paradigmatic CLP language (CP[!,|,&,;]) providing
a reasonably complete set of control structures for the parallel
exploration of the refutation search space, and,
-- an extensive comparison of CLP languages with related
computational models outside the realm of logic programming,
such as Actors, CSP, data-flow languages (including the
systolic computational model) and constraint-based languages
-- theoretical computer science via an understanding of the formal
(operational and denotational) semantics of, and reasoning systems
for, concurrent logic languages, including an understanding of
the `logic' in such languages,
-- programming language implementation, via a compiler-based
implementation of the specific concurrent language CP[!,|,&]
targetted to a uniprocessor machine,
-- the `correct' design of efficient concurrent algorithms in the
framework of unification-based concurrent logic programming
languages,
-- knowledge representation languages, via the design of a
`higher-level' object-oriented, schema-based language
featuring multiple inheritance with exceptions, and its
implementation in Cp[!,|,&].
------------------------------
Date: Wed, 23 Oct 85 13:52:25 PDT
From: admin@cogsci.Berkeley.EDU (Cognitive Science Program)
Subject: Seminar - Person Schemata (UCB)
BERKELEY COGNITIVE SCIENCE PROGRAM
Fall 1985
Cognitive Science Seminar - IDS 237A
Tuesday, October 29, 11:00 - 12:30
240 Bechtel Engineering Center
Discussion: 12:30 - 1:30 in 200 Building T-4
``Person Schemata''
Mardi J. Horowitz M.D.
Professor of Psychiatry, U.C.S.F.
The speaker directs the recently formed Program on Cons-
cious and Unconscious Processes of the John and Catherine T.
MacArthur Foundation. Research on person schemata is one of
the core agendas of this program.
After a brief description of the program, the discussion
will focus on clinical phenomena as segmented by different
states of mind in a single individual. By examining the confi-
guration in each state of mind as it occurs over time, it may
be possible to infer what the self schemata and role relation-
ship models are that organize thoughts, feelings and action
into observed patterns. The theory that forms the basis for
such inferences includes the postulate that each person's
overall self organization may include a partially nested
hierarchy of multiple self-concepts. A frequent set of states
of mind in pathological grief reactions will provide a concrete
illustration of phenomena, methods of inference, and a theory
of person schemata.
------------------------------
Date: Wed, 23 Oct 85 16:43 EDT
From: Tim Finin <Tim%upenn.csnet@CSNET-RELAY.ARPA>
Subject: Seminar - NETTALK: Connectionist Speech Learning (UPenn)
Colloquium - University Of Pennsylvania
3pm 10-29-85, 216 Moore
NETTALK: TEACHING A MASSIVELY-PARALLEL NETWORK TO TALK
Terrence J. Sejnowski
Biophysics Department, Johns Hopkins University
Text to speech is a difficult problem for rule-based systems because English
pronunciation is highly context dependent and there are many exceptions to
phonological rules. A more suitable knowledge representation for
correspondences between letters and phonemes will be described in which rules
and exceptions are treated uniformly and can be determined with a learning
algorithm. The architecture is a layered network of several hundred simple
processing units with several thousand weights on the connections between the
units. The training corpus is continuous informal speech transcribed from tape
recordings. Following training on 1000 words from this corpus the network can
generalize to novel text. Even though this network was not designed to mimic
human learning, the development of the network in some respects resembles the
early stages in human language acquisition. It is conjectured that the
parallel architecture and learning algorithm will also be effective on other
problems which depend on evidential reasoning from previous experience.
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End of AIList Digest
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