clarke@utcsri.UUCP (Jim Clarke) (02/23/87)
(SF = Sandford Fleming Building, 10 King's College Road)
(GB = Galbraith Building, 35 St. George Street)
SUMMARY:
Tuesday, March 3, 11 am, SF1101: Jerome Feldman (title TBA)
Tuesday, March 3, 3 pm, GB 120: Jim Delgrande (title TBA)
Tuesday, March 3, 4 pm, GB221: Josef Saad
``Sparse Matrix Computations on Parallel Machines"
Thursday, March 5, 11 am, GB220: Michael Schwartz
``Naming in Large Heterogeneous Systems"
Thursday, March 5, 3 pm, GB220: Gaston Gonnet
``The Use of Many-to-One Mappings for Algebraic Pattern Matching"
-------------------
COLLOQUIUM, Tuesday, March 3, 11 am, SF1101
Professor Jerome Feldman
University of Rochester
Title: TO BE ANNOUNCED
A.I. SEMINAR, Tuesday, March 3, 3 pm, GB 120
Professor Jim Delgrande
Simon Fraser University
Title: TO BE ANNOUNCED
NUMERICAL ANALYSIS SEMINAR, Tuesday, March 3, 4 pm, GB221
Professor Josef Saad
University of Illinois
``Sparse Matrix Computations
on Parallel Machines"
This talk will describe the difficulties encountered when solving
large sparse matrix problems on parallel machines and propose a few tenta-
tive solutions. We will start by presenting a brief overview of the dif-
ferent techniques used (direct and iterative methods) as well as the data
structures employed. These methods suffer from numerous bottlenecks when
implemented in parallel or vector machines. We will focus on iterative
methods which are usually much faster than direct methods for very large
problems, although often not as reliable. Work remains to be done to
improve the robustness of the standard preconditioning techniques by, for
example, incorporating pivoting in the incomplete LU factorizations. On
parallel machines, most of the standard preconditioners such as those based
on incomplete LU factorization, are inherently sequential. A class of
preconditioners that appears promising for general sparse matrices is that
of polynomial preconditionings. We will explain this by comparing the per-
formances of different ways of implementing matrix by vector multiplica-
tions on the Alliant FX/8. Finally, a few preliminary tests with a code
based on polynomial preconditioning on the Alliant FX/8 will be reported.
SYSTEMS SEMINAR, Thursday, March 5, 11 am, GB220
Professor Michael Schwartz
University of Washington
``Naming in Large Heterogeneous Systems"
This talk will discuss an approach to naming in evolving systems that
are composed of a heterogeneous collection of subsystems. Our goal is
to reduce the cost of integrating new system types into an exist-
ing environment. Providing a naming service in such an environment
is difficult because each of the systems being integrated typically uses
its own naming service.
The obvious approach is to implement a new standard to which the existing
subsystems must adhere. However, several problems with such
standardization render it unsuitable for the environment we are
addressing. We present a new approach based on integrating existing name
spaces through a structure that separates global name space
administration from knowledge of the semantics of naming in each of the
assimilated subsystems.
A major advantage of this approach is ease of integration: newly added
system types can participate in the larger system without modification.
At the same time, systems that use the global naming service can take
advantage of the services provided by new systems without modification.
In addition, the model has broader applicability than the applications
typically associated with naming. It can, for example, form the basis
for a file system that integrates a heterogeneous collection of existing
file systems.
A prototype implementation has been built in conjunction with the
Heterogeneous Computer Systems project at the University of Washington,
and is being used as a basis for developing several heterogeneous
applications. Analysis of measurements indicates the applicability of
caching at various levels of the system.
THEORY SEMINAR, Thursday, March 5, 3 pm, GB220
Professor Gaston Gonnet
University of Waterloo
``The Use of Many-to-One Mappings
for Algebraic Pattern Matching"
--
Jim Clarke -- Dept. of Computer Science, Univ. of Toronto, Canada M5S 1A4
(416) 978-4058
{allegra,cornell,decvax,linus,utzoo}!utcsri!clarke