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\section{Data-Intensive Applications:
Expert Systems}

\subsection{
Application Description}

Many functions in today's world can benefit by access
to expert systems.  These systems will monitor people providing
information and making decisions and then detect when and what type of
advice might be helpful.  Areas that could benefit from these systems
include manufacturing design, legal affairs, and defense.  Perhaps one
of the most interesting and potentially beneficial applications of
expert systems is in the area of medical diagnosis and treatment.
The following are several feasible implementations of expert systems
for health care.

When John or Jane Doe visits the clinic, the patient interview will
essentially be conducted by a powerful computer system.  Neural-net
software will guide the selection of appropriate questions which will,
with high confidence, maximize the relevance of received data from the
patient's own experience.  Voice recognition will transcribe the
interview.  Sensors will read the physical expressions and mannerisms
during this process and judge the credibility of the patient's
comments, all in the context of their cultural mannerisms.  Sensors
will also measure the patient's physiological condition.

The diagnosis will be made with the help of captured wisdom from
legions of medical professionals and increasingly with the additional
knowledge being gained by the system over time.  Intensive patient
follow-up will detect faulty decisions and provide learning for the
benefit of future benefits.

For patients taking medication, the system will thoroughly analyze
possible side-effects and multiple drug interactions.  Based upon the
accumulated experience of other patients with correlating symptoms,
only relevant tests will be ordered.  X-rays will be image enhanced
and ``read'' by a computer-resident radiologist agent and matched to a
vast X-ray database.  Customized profiles for radiation treatment will
be available in real-time and based upon immediate image feedback.
When warranted, medication will be synthesized to work most
effectively with the patient's particular DNA structure and associated
immune system.  Surgical procedures will become semi-automated; in
many cases, fully automated surgical robotics will be on the horizon.

In cases where natural organ and bone marrow transplants are required,
the data from an international registry system will be available.
Patients' lifestyle data plus data from routine physical examinations
will provide customized risk profiles which, with high confidence,
will statistically assess the consequences lifestyle decisions.  The
risk of environmental hazards will be quantified and increasingly
correlated to health histories of individuals, resulting in high
societal motivation to lower risk.


\subsection{Architecture Questions}

Total memory requirements for thousands of users will be in
the megabyte to petabyte range.
We also estimate that the total input/output will be
(potentially) a gigabyte to a terabyte per second.

We stress, however, that
it is difficult to determine the
exact architecture requirements for expert systems. 
Such factors as
memory characteristics of the working set,
memory access properties, communications,
major data structure (size of operands),
and execution (including number and granularity of parallel
activities, workload dynamic instruction count and mix, critical
path lengths and parallelism with scaling, data lifetime and sharing, and
global barriers and synchronization points)
will depend on the specific application.

Indeed, we expect that 
expert systems will involve a wide range of application elements (data
collection, data interpretation, database searching, neural networks,
visualization, sorting, table lookup, pattern matching) and thus 
will require a hierarchy of computing capabilities.  The integration
of these capabilities will probably be the most important technology
development required for this application.

\subsection{Conclusion}
There does not appear to be a
clear and compelling case for the need for petaFLOPS/petaBYTEs computers
for expert systems.  This application is clearly data intensive, but
it is unclear that a single computer would be needed to support the
users of such an application.  It does not seem feasible that an single
user of an expert system would require very fast access to a petabyte
of data.  Rather, we expect thousands (and perhaps millions) of
users who would need access to smaller data sets.  We also do not
expect that a single user would need a petaFLOP of computational
power.  Most of the envisioned elements of expert systems (data
collection, data interpretation, database searching, neural networks,
visualization, etc.) would require only gigaFLOPS or perhaps teraFLOPS of
computational power. 

A more likely
approach for the deployment of expert systems will be a hierarchy of
computers and storage devices.  In fact, potential developers and users of
expert systems would probably find it very inhibiting if this
application required what is expected to be a $1 billion 
system.
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