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From: clarke@utcsri.UUCP (Jim Clarke)
Newsgroups: ont.events
Subject: U of Toronto Computer Science activities, Dec. 1-5
Message-ID: <3690@utcsri.UUCP>
Date: Tue, 25-Nov-86 11:49:37 EST
Article-I.D.: utcsri.3690
Posted: Tue Nov 25 11:49:37 1986
Date-Received: Tue, 25-Nov-86 12:27:00 EST
Distribution: ont
Organization: CSRI, University of Toronto
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              (GB = Galbraith Building, 35 St. George Street)


A.I. SEMINAR, Tuesday, December 2, 3 pm, GB 119

                         Professor Michael Leyton
                          Computer Science, SUNY

                       "A Process Grammar for Shape"

     A computational theory is offered of the way in which process-history
is recovered from shape.  It is claimed that curvature extrema are cru-
cially used in the inference of processes from shape, and rules are
developed that formalize the inference procedure.  We then establish a
process-grammar of only six types of operations to express the relationship
between any two given shapes such that one shape is represented as a later
stage in the development of the other; i.e. one shape is described as the
extrapolation of processes inferred in the other under the above inference
rules.  More formally, a deformation is expressed as a transformation of
process-records  - a technique reminiscent of Chomsky's description of
linguistic transformations in terms of transitions between phrase-structure
trees.  In the present case, our process-grammar has the psychological role
of explaining the curvature extrema in terms of a sequence of psychologi-
cally meaningful deformations.  We find that the grammar thereby stratifies
shape-space into several intersecting systems of strata, where each
strata-system represents a particular process-history of successive modifi-
cation.
-- 

Jim Clarke -- Dept. of Computer Science, Univ. of Toronto, Canada M5S 1A4
              (416) 978-4058
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