clarke@csri.toronto.edu (Jim Clarke) (01/16/89)
ACTIVITIES FOR THE WEEK COMMENCING JANUARY 30, 1989
(SF = Sandford Fleming Building, 10 King's College Road)
(GB = Galbraith Building, 35 St. George Street)
SUMMARY:
TECHNICAL PRESENTATION - Tues., Jan. 31, 3 p.m. in GB 248 -- Germaine Gaudet
"Parallel Processing on the Sequent Multiprocessor"
AI SEMINAR - Thurs., Feb. 2, 11 a.m. in SF 1105 -- Terry Caelli
"Optimal Filters For Image Segmentation And Object Recognition"
THEORY/SYSTEMS SEMINAR - Thurs., Feb. 2, 3 p.m. in GB 244 -- Nir Shavit
"Bounded Concurrent Time-Stamp Systems Are Constructible"
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TECHNICAL PRESENTATION - Tuesday, January 31, 3 p.m. in Room GB 248
Germaine Gaudet
Sequent Corportion
"Parallel Processing on the Sequent Multiprocessor"
This presentation will give an overview of the architecture of
the Sequent multiprocessors, and will describe how they can be
used for parallel processing. Information about performance re-
lative to other machines and architectures will be included.
AI SEMINAR - Thursday, February 2, 11 a.m. in Room SF 1105
Terry Caelli
Queens University
"Optimal Filters For Image Segmentation And Object Recognition"
In this presentation we consider how filters can be estimated and
used to improve the processes of image segmentation and the
recognition of the resultant parts invariant to specific
transformations and projections. Of specific importance to deriv-
ing such filters are the types of constraints the filters are
aimed at satisfying and what associated normalization functions
are required. Examples from texture segmentation and invariant
pattern/ object recognition will be used to illustrate this ap-
proach.
THEORY/SYSTEMS SEMINAR - Thursday, February 2, 3 p.m. in Room GB 244
Nir Shavit
Hebrew University
"Bounded Concurrent Time-Stamp Systems Are Constructible"
Concurrent time stamping is at the heart of solutions to some of
the most fundamental problems in distributed computing. Con-
structions of bounded time-stamp schemes for the sequential case
have been shown by Israeli and Li [IL87]. Unfortunately, the only
known implementation of a concurrent-time-stamp-system is
theoretically unsatisfying, since it requires unbounded size
time-stamps, in other words, unbounded memory. Not knowing if
bounded concurrent-time-stamp-systems are at all constructible,
researchers were led to constructing complicated problem-specific
solutions to replace the simple unbounded ones. In this work,
for the first time, a bounded implementation of a concurrent-
time-stamp-system is presented. It provides a modular unbounded-
to-bounded transformation of the simple unbounded solutions to
problems such as above. It allows solutions to two formerly open
problems, the bounded-probabilistic-consensus problem of Abraham-
son [A88] and the fifo-l-exclusion problem of [FLBB85], and a
more efficient construction of mrmw atomic registers.
Joint work with Danny Dolev
--
Jim Clarke -- Dept. of Computer Science, Univ. of Toronto, Canada M5S 1A4
(416) 978-4058
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