<s>
In	O
artificial	B-Application
intelligence	I-Application
,	O
an	O
expert	B-Application
system	I-Application
is	O
a	O
computer	O
system	O
emulating	O
the	O
decision-making	O
ability	O
of	O
a	O
human	O
expert	O
.	O
</s>
<s>
Expert	B-Application
systems	I-Application
are	O
designed	O
to	O
solve	O
complex	O
problems	O
by	O
reasoning	B-Application
through	O
bodies	O
of	O
knowledge	O
,	O
represented	O
mainly	O
as	O
if	O
–	O
then	O
rules	O
rather	O
than	O
through	O
conventional	O
procedural	B-Application
code	I-Application
.	O
</s>
<s>
The	O
first	O
expert	B-Application
systems	I-Application
were	O
created	O
in	O
the	O
1970s	O
and	O
then	O
proliferated	O
in	O
the	O
1980s	O
.	O
</s>
<s>
Expert	B-Application
systems	I-Application
were	O
among	O
the	O
first	O
truly	O
successful	O
forms	O
of	O
artificial	B-Application
intelligence	I-Application
(	O
AI	B-Application
)	O
software	O
.	O
</s>
<s>
An	O
expert	B-Application
system	I-Application
is	O
divided	O
into	O
two	O
subsystems	O
:	O
the	O
inference	O
engine	O
and	O
the	O
knowledge	O
base	O
.	O
</s>
<s>
These	O
systems	O
were	O
often	O
described	O
as	O
the	O
early	O
forms	O
of	O
expert	B-Application
systems	I-Application
.	O
</s>
<s>
This	O
previous	O
situation	O
gradually	O
led	O
to	O
the	O
development	O
of	O
expert	B-Application
systems	I-Application
,	O
which	O
used	O
knowledge-based	O
approaches	O
.	O
</s>
<s>
These	O
expert	B-Application
systems	I-Application
in	O
medicine	O
were	O
the	O
MYCIN	O
expert	B-Application
system	I-Application
,	O
the	O
Internist-I	O
expert	B-Application
system	I-Application
and	O
later	O
,	O
in	O
the	O
middle	O
of	O
the	O
1980s	O
,	O
the	O
CADUCEUS	O
.	O
</s>
<s>
Expert	B-Application
systems	I-Application
were	O
formally	O
introduced	O
around	O
1965	O
by	O
the	O
Stanford	O
Heuristic	O
Programming	O
Project	O
led	O
by	O
Edward	O
Feigenbaum	O
,	O
who	O
is	O
sometimes	O
termed	O
the	O
"	O
father	O
of	O
expert	B-Application
systems	I-Application
"	O
;	O
other	O
key	O
early	O
contributors	O
were	O
Bruce	O
Buchanan	O
and	O
Randall	O
Davis	O
.	O
</s>
<s>
Expert	B-Application
systems	I-Application
became	O
some	O
of	O
the	O
first	O
truly	O
successful	O
forms	O
of	O
artificial	B-Application
intelligence	I-Application
(	O
AI	B-Application
)	O
software	O
.	O
</s>
<s>
Research	O
on	O
expert	B-Application
systems	I-Application
was	O
also	O
active	O
in	O
France	O
.	O
</s>
<s>
While	O
in	O
the	O
US	O
the	O
focus	O
tended	O
to	O
be	O
on	O
rules-based	O
systems	O
,	O
first	O
on	O
systems	O
hard	O
coded	O
on	O
top	O
of	O
LISP	B-Language
programming	O
environments	O
and	O
then	O
on	O
expert	B-Application
system	I-Application
shells	O
developed	O
by	O
vendors	O
such	O
as	O
Intellicorp	O
,	O
in	O
France	O
research	O
focused	O
more	O
on	O
systems	O
developed	O
in	O
Prolog	B-Language
.	O
</s>
<s>
The	O
advantage	O
of	O
expert	B-Application
system	I-Application
shells	O
was	O
that	O
they	O
were	O
somewhat	O
easier	O
for	O
nonprogrammers	O
to	O
use	O
.	O
</s>
<s>
The	O
advantage	O
of	O
Prolog	B-Language
environments	O
was	O
that	O
they	O
were	O
not	O
focused	O
only	O
on	O
if-then	O
rules	O
;	O
Prolog	B-Language
environments	O
provided	O
a	O
much	O
better	O
realization	O
of	O
a	O
complete	O
first	O
order	O
logic	O
environment	O
.	O
</s>
<s>
In	O
the	O
1980s	O
,	O
expert	B-Application
systems	I-Application
proliferated	O
.	O
</s>
<s>
Universities	O
offered	O
expert	B-Application
system	I-Application
courses	O
and	O
two-thirds	O
of	O
the	O
Fortune	O
500	O
companies	O
applied	O
the	O
technology	O
in	O
daily	O
business	O
activities	O
.	O
</s>
<s>
Interest	O
was	O
international	O
with	O
the	O
Fifth	B-Device
Generation	I-Device
Computer	I-Device
Systems	I-Device
project	I-Device
in	O
Japan	O
and	O
increased	O
research	O
funding	O
in	O
Europe	O
.	O
</s>
<s>
In	O
1981	O
,	O
the	O
first	O
IBM	B-Device
PC	I-Device
,	O
with	O
the	O
PC	B-Operating_System
DOS	I-Operating_System
operating	O
system	O
,	O
was	O
introduced	O
.	O
</s>
<s>
The	O
imbalance	O
between	O
the	O
high	O
affordability	O
of	O
the	O
relatively	O
powerful	O
chips	O
in	O
the	O
PC	O
,	O
compared	O
to	O
the	O
much	O
more	O
expensive	O
cost	O
of	O
processing	O
power	O
in	O
the	O
mainframes	O
that	O
dominated	O
the	O
corporate	O
IT	O
world	O
at	O
the	O
time	O
,	O
created	O
a	O
new	O
type	O
of	O
architecture	O
for	O
corporate	O
computing	O
,	O
termed	O
the	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
model	I-Operating_System
.	O
</s>
<s>
Calculations	O
and	O
reasoning	B-Application
could	O
be	O
performed	O
at	O
a	O
fraction	O
of	O
the	O
price	O
of	O
a	O
mainframe	O
using	O
a	O
PC	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
client-server	B-Operating_System
had	O
a	O
tremendous	O
impact	O
on	O
the	O
expert	B-Application
systems	I-Application
market	O
.	O
</s>
<s>
Expert	B-Application
systems	I-Application
were	O
already	O
outliers	O
in	O
much	O
of	O
the	O
business	O
world	O
,	O
requiring	O
new	O
skills	O
that	O
many	O
IT	O
departments	O
did	O
not	O
have	O
and	O
were	O
not	O
eager	O
to	O
develop	O
.	O
</s>
<s>
Until	O
then	O
,	O
the	O
main	O
development	O
environment	O
for	O
expert	B-Application
systems	I-Application
had	O
been	O
high	O
end	O
Lisp	B-Operating_System
machines	I-Operating_System
from	O
Xerox	O
,	O
Symbolics	O
,	O
and	O
Texas	O
Instruments	O
.	O
</s>
<s>
With	O
the	O
rise	O
of	O
the	O
PC	O
and	O
client-server	B-Operating_System
computing	I-Operating_System
,	O
vendors	O
such	O
as	O
Intellicorp	O
and	O
Inference	O
Corporation	O
shifted	O
their	O
priorities	O
to	O
developing	O
PC-based	O
tools	O
.	O
</s>
<s>
The	O
first	O
expert	B-Application
system	I-Application
to	O
be	O
used	O
in	O
a	O
design	O
capacity	O
for	O
a	O
large-scale	O
product	O
was	O
the	O
SID	O
(	O
Synthesis	O
of	O
Integral	O
Design	O
)	O
software	O
program	O
,	O
developed	O
in	O
1982	O
.	O
</s>
<s>
Written	O
in	O
LISP	B-Language
,	O
SID	O
generated	O
93%	O
of	O
the	O
VAX	B-Device
9000	I-Device
CPU	B-General_Concept
logic	O
gates	O
.	O
</s>
<s>
It	O
was	O
terminated	O
by	O
logic	O
designers	O
after	O
the	O
VAX	B-Device
9000	I-Device
project	O
completion	O
.	O
</s>
<s>
During	O
the	O
years	O
before	O
the	O
middle	O
of	O
the	O
1970s	O
,	O
the	O
expectations	O
of	O
what	O
expert	B-Application
systems	I-Application
can	O
accomplish	O
in	O
many	O
fields	O
tended	O
to	O
be	O
extremely	O
optimistic	O
.	O
</s>
<s>
At	O
the	O
beginning	O
of	O
these	O
early	O
studies	O
,	O
researchers	O
were	O
hoping	O
to	O
develop	O
entirely	O
automatic	O
(	O
i.e.	O
,	O
completely	O
computerized	O
)	O
expert	B-Application
systems	I-Application
.	O
</s>
<s>
Many	O
of	O
the	O
computational	O
problems	O
related	O
to	O
this	O
type	O
of	O
expert	B-Application
systems	I-Application
have	O
certain	O
pragmatic	O
limitations	O
.	O
</s>
<s>
In	O
the	O
1990s	O
and	O
beyond	O
,	O
the	O
term	O
expert	B-Application
system	I-Application
and	O
the	O
idea	O
of	O
a	O
standalone	O
AI	B-Application
system	O
mostly	O
dropped	O
from	O
the	O
IT	O
lexicon	O
.	O
</s>
<s>
One	O
is	O
that	O
"	O
expert	B-Application
systems	I-Application
failed	O
"	O
:	O
the	O
IT	O
world	O
moved	O
on	O
because	O
expert	B-Application
systems	I-Application
did	O
not	O
deliver	O
on	O
their	O
over	O
hyped	O
promise	O
.	O
</s>
<s>
The	O
other	O
is	O
the	O
mirror	O
opposite	O
,	O
that	O
expert	B-Application
systems	I-Application
were	O
simply	O
victims	O
of	O
their	O
success	O
:	O
as	O
IT	O
professionals	O
grasped	O
concepts	O
such	O
as	O
rule	O
engines	O
,	O
such	O
tools	O
migrated	O
from	O
being	O
standalone	O
tools	O
for	O
developing	O
special	O
purpose	O
expert	B-Application
systems	I-Application
,	O
to	O
being	O
one	O
of	O
many	O
standard	O
tools	O
.	O
</s>
<s>
Other	O
researchers	O
suggest	O
that	O
Expert	B-Application
Systems	I-Application
caused	O
inter-company	O
power	O
struggles	O
when	O
the	O
IT	O
organization	O
lost	O
its	O
exclusivity	O
in	O
software	O
modifications	O
to	O
users	O
or	O
Knowledge	O
Engineers	O
.	O
</s>
<s>
Many	O
of	O
the	O
leading	O
major	O
business	O
application	O
suite	O
vendors	O
(	O
such	O
as	O
SAP	B-Application
,	O
Siebel	O
,	O
and	O
Oracle	B-Application
)	O
integrated	O
expert	B-Application
system	I-Application
abilities	O
into	O
their	O
suite	O
of	O
products	O
as	O
a	O
way	O
of	O
specifying	O
business	O
logic	O
–	O
rule	O
engines	O
are	O
no	O
longer	O
simply	O
for	O
defining	O
the	O
rules	O
an	O
expert	O
would	O
use	O
but	O
for	O
any	O
type	O
of	O
complex	O
,	O
volatile	O
,	O
and	O
critical	O
business	O
logic	O
;	O
they	O
often	O
go	O
hand	O
in	O
hand	O
with	O
business	O
process	O
automation	O
and	O
integration	O
environments	O
.	O
</s>
<s>
The	O
limitations	O
of	O
the	O
previous	O
type	O
of	O
expert	B-Application
systems	I-Application
have	O
urged	O
researchers	O
to	O
develop	O
new	O
types	O
of	O
approaches	O
.	O
</s>
<s>
Some	O
of	O
the	O
approaches	O
that	O
researchers	O
have	O
developed	O
are	O
based	O
on	O
new	O
methods	O
of	O
artificial	B-Application
intelligence	I-Application
(	O
AI	B-Application
)	O
,	O
and	O
in	O
particular	O
in	O
machine	O
learning	O
and	O
data	B-Application
mining	I-Application
approaches	O
with	O
a	O
feedback	O
mechanism	O
.	O
</s>
<s>
Recurrent	B-Algorithm
neural	I-Algorithm
networks	I-Algorithm
often	O
take	O
advantage	O
of	O
such	O
mechanisms	O
.	O
</s>
<s>
Related	O
is	O
the	O
subject	O
of	O
big	B-Application
data	I-Application
here	O
.	O
</s>
<s>
Sometimes	O
these	O
type	O
of	O
expert	B-Application
systems	I-Application
are	O
called	O
"	O
intelligent	O
systems.	O
"	O
</s>
<s>
An	O
expert	B-Application
system	I-Application
is	O
an	O
example	O
of	O
a	O
knowledge-based	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Expert	B-Application
systems	I-Application
were	O
the	O
first	O
commercial	O
systems	O
to	O
use	O
a	O
knowledge-based	O
architecture	O
.	O
</s>
<s>
In	O
general	O
view	O
,	O
an	O
expert	B-Application
system	I-Application
includes	O
the	O
following	O
components	O
:	O
a	O
knowledge	O
base	O
,	O
an	O
inference	O
engine	O
,	O
an	O
explanation	O
facility	O
,	O
a	O
knowledge	O
acquisition	O
facility	O
,	O
and	O
a	O
user	O
interface	O
.	O
</s>
<s>
In	O
early	O
expert	B-Application
systems	I-Application
such	O
as	O
Mycin	O
and	O
Dendral	O
,	O
these	O
facts	O
were	O
represented	O
mainly	O
as	O
flat	O
assertions	O
about	O
variables	O
.	O
</s>
<s>
In	O
later	O
expert	B-Application
systems	I-Application
developed	O
with	O
commercial	O
shells	O
,	O
the	O
knowledge	O
base	O
took	O
on	O
more	O
structure	O
and	O
used	O
concepts	O
from	O
object-oriented	O
programming	O
.	O
</s>
<s>
The	O
inference	O
engine	O
is	O
an	O
automated	B-Application
reasoning	I-Application
system	I-Application
that	O
evaluates	O
the	O
current	O
state	O
of	O
the	O
knowledge-base	O
,	O
applies	O
relevant	O
rules	O
,	O
and	O
then	O
asserts	O
new	O
knowledge	O
into	O
the	O
knowledge	O
base	O
.	O
</s>
<s>
The	O
inference	O
engine	O
may	O
also	O
include	O
abilities	O
for	O
explanation	O
,	O
so	O
that	O
it	O
can	O
explain	O
to	O
a	O
user	O
the	O
chain	O
of	O
reasoning	B-Application
used	O
to	O
arrive	O
at	O
a	O
particular	O
conclusion	O
by	O
tracing	O
back	O
over	O
the	O
firing	O
of	O
rules	O
that	O
resulted	O
in	O
the	O
assertion	O
.	O
</s>
<s>
It	O
would	O
match	O
R1	B-Application
and	O
assert	O
Mortal(Socrates )	O
into	O
the	O
knowledge	O
base	O
.	O
</s>
<s>
So	O
if	O
the	O
system	O
was	O
trying	O
to	O
determine	O
if	O
Mortal(Socrates )	O
is	O
true	O
it	O
would	O
find	O
R1	B-Application
and	O
query	O
the	O
knowledge	O
base	O
to	O
see	O
if	O
Man(Socrates )	O
is	O
true	O
.	O
</s>
<s>
One	O
of	O
the	O
early	O
innovations	O
of	O
expert	B-Application
systems	I-Application
shells	O
was	O
to	O
integrate	O
inference	O
engines	O
with	O
a	O
user	O
interface	O
.	O
</s>
<s>
So	O
in	O
this	O
example	O
,	O
it	O
could	O
use	O
R1	B-Application
to	O
ask	O
the	O
user	O
if	O
Socrates	O
was	O
a	O
Man	O
and	O
then	O
use	O
that	O
new	O
information	O
accordingly	O
.	O
</s>
<s>
In	O
the	O
simple	O
example	O
above	O
if	O
the	O
system	O
had	O
used	O
R1	B-Application
to	O
assert	O
that	O
Socrates	O
was	O
Mortal	O
and	O
a	O
user	O
wished	O
to	O
understand	O
why	O
Socrates	O
was	O
mortal	O
they	O
could	O
query	O
the	O
system	O
and	O
the	O
system	O
would	O
look	O
back	O
at	O
the	O
rules	O
which	O
fired	O
to	O
cause	O
the	O
assertion	O
and	O
present	O
those	O
rules	O
to	O
the	O
user	O
as	O
an	O
explanation	O
.	O
</s>
<s>
As	O
expert	B-Application
systems	I-Application
evolved	O
,	O
many	O
new	O
techniques	O
were	O
incorporated	O
into	O
various	O
types	O
of	O
inference	O
engines	O
.	O
</s>
<s>
Hypothetical	O
reasoning	B-Application
.	O
</s>
<s>
Simple	O
probabilities	O
were	O
extended	O
in	O
some	O
systems	O
with	O
sophisticated	O
mechanisms	O
for	O
uncertain	O
reasoning	B-Application
,	O
such	O
as	O
Fuzzy	O
logic	O
,	O
and	O
combination	O
of	O
probabilities	O
.	O
</s>
<s>
With	O
the	O
addition	O
of	O
object	O
classes	O
to	O
the	O
knowledge	O
base	O
,	O
a	O
new	O
type	O
of	O
reasoning	B-Application
was	O
possible	O
.	O
</s>
<s>
Along	O
with	O
reasoning	B-Application
simply	O
about	O
object	O
values	O
,	O
the	O
system	O
could	O
also	O
reason	O
about	O
object	O
structures	O
.	O
</s>
<s>
In	O
this	O
simple	O
example	O
,	O
Man	O
can	O
represent	O
an	O
object	O
class	O
and	O
R1	B-Application
can	O
be	O
redefined	O
as	O
a	O
rule	O
that	O
defines	O
the	O
class	O
of	O
all	O
men	O
.	O
</s>
<s>
These	O
types	O
of	O
special	O
purpose	O
inference	O
engines	O
are	O
termed	O
classifiers	B-Algorithm
.	O
</s>
<s>
Although	O
they	O
were	O
not	O
highly	O
used	O
in	O
expert	B-Application
systems	I-Application
,	O
classifiers	B-Algorithm
are	O
very	O
powerful	O
for	O
unstructured	O
volatile	O
domains	O
,	O
and	O
are	O
a	O
key	O
technology	O
for	O
the	O
Internet	O
and	O
the	O
emerging	O
Semantic	O
Web	O
.	O
</s>
<s>
The	O
goal	O
of	O
knowledge-based	B-General_Concept
systems	I-General_Concept
is	O
to	O
make	O
the	O
critical	O
information	O
required	O
for	O
the	O
system	O
to	O
work	O
explicit	O
rather	O
than	O
implicit	O
.	O
</s>
<s>
With	O
an	O
expert	B-Application
system	I-Application
the	O
goal	O
was	O
to	O
specify	O
the	O
rules	O
in	O
a	O
format	O
that	O
was	O
intuitive	O
and	O
easily	O
understood	O
,	O
reviewed	O
,	O
and	O
even	O
edited	O
by	O
domain	O
experts	O
rather	O
than	O
IT	O
experts	O
.	O
</s>
<s>
First	O
,	O
by	O
removing	O
the	O
need	O
to	O
write	O
conventional	O
code	O
,	O
many	O
of	O
the	O
normal	O
problems	O
that	O
can	O
be	O
caused	O
by	O
even	O
small	O
changes	O
to	O
a	O
system	O
could	O
be	O
avoided	O
with	O
expert	B-Application
systems	I-Application
.	O
</s>
<s>
This	O
also	O
was	O
a	O
reason	O
for	O
the	O
second	O
benefit	O
:	O
rapid	B-Device
prototyping	I-Device
.	O
</s>
<s>
With	O
an	O
expert	B-Application
system	I-Application
shell	O
it	O
was	O
possible	O
to	O
enter	O
a	O
few	O
rules	O
and	O
have	O
a	O
prototype	O
developed	O
in	O
days	O
rather	O
than	O
the	O
months	O
or	O
year	O
typically	O
associated	O
with	O
complex	O
IT	O
projects	O
.	O
</s>
<s>
A	O
claim	O
for	O
expert	B-Application
system	I-Application
shells	O
that	O
was	O
often	O
made	O
was	O
that	O
they	O
removed	O
the	O
need	O
for	O
trained	O
programmers	O
and	O
that	O
experts	O
could	O
develop	O
systems	O
themselves	O
.	O
</s>
<s>
While	O
the	O
rules	O
for	O
an	O
expert	B-Application
system	I-Application
were	O
more	O
comprehensible	O
than	O
typical	O
computer	O
code	O
,	O
they	O
still	O
had	O
a	O
formal	O
syntax	O
where	O
a	O
misplaced	O
comma	O
or	O
other	O
character	O
could	O
cause	O
havoc	O
as	O
with	O
any	O
other	O
computer	O
language	O
.	O
</s>
<s>
Also	O
,	O
as	O
expert	B-Application
systems	I-Application
moved	O
from	O
prototypes	O
in	O
the	O
lab	O
to	O
deployment	O
in	O
the	O
business	O
world	O
,	O
issues	O
of	O
integration	O
and	O
maintenance	O
became	O
far	O
more	O
critical	O
.	O
</s>
<s>
Summing	O
up	O
the	O
benefits	O
of	O
using	O
expert	B-Application
systems	I-Application
,	O
the	O
following	O
can	O
be	O
highlighted	O
:	O
</s>
<s>
Multiple	O
expertise	O
:	O
Several	O
expert	B-Application
systems	I-Application
can	O
be	O
run	O
simultaneously	O
to	O
solve	O
a	O
problem	O
.	O
</s>
<s>
Explanation	O
:	O
Expert	B-Application
systems	I-Application
always	O
describe	O
of	O
how	O
the	O
problem	O
was	O
solved	O
.	O
</s>
<s>
Fast	O
response	O
:	O
The	O
expert	B-Application
systems	I-Application
are	O
fast	O
and	O
able	O
to	O
solve	O
a	O
problem	O
in	O
real-time	O
.	O
</s>
<s>
The	O
most	O
common	O
disadvantage	O
cited	O
for	O
expert	B-Application
systems	I-Application
in	O
the	O
academic	O
literature	O
is	O
the	O
knowledge	O
acquisition	O
problem	O
.	O
</s>
<s>
Obtaining	O
the	O
time	O
of	O
domain	O
experts	O
for	O
any	O
software	O
application	O
is	O
always	O
difficult	O
,	O
but	O
for	O
expert	B-Application
systems	I-Application
it	O
was	O
especially	O
difficult	O
because	O
the	O
experts	O
were	O
by	O
definition	O
highly	O
valued	O
and	O
in	O
constant	O
demand	O
by	O
the	O
organization	O
.	O
</s>
<s>
As	O
a	O
result	O
of	O
this	O
problem	O
,	O
a	O
great	O
deal	O
of	O
research	O
in	O
the	O
later	O
years	O
of	O
expert	B-Application
systems	I-Application
was	O
focused	O
on	O
tools	O
for	O
knowledge	O
acquisition	O
,	O
to	O
help	O
automate	O
the	O
process	O
of	O
designing	O
,	O
debugging	O
,	O
and	O
maintaining	O
rules	O
defined	O
by	O
experts	O
.	O
</s>
<s>
However	O
,	O
when	O
looking	O
at	O
the	O
life-cycle	O
of	O
expert	B-Application
systems	I-Application
in	O
actual	O
use	O
,	O
other	O
problems	O
–	O
essentially	O
the	O
same	O
problems	O
as	O
those	O
of	O
any	O
other	O
large	O
system	O
–	O
seem	O
at	O
least	O
as	O
critical	O
as	O
knowledge	O
acquisition	O
:	O
integration	O
,	O
access	O
to	O
large	O
databases	O
,	O
and	O
performance	O
.	O
</s>
<s>
Performance	O
could	O
be	O
especially	O
problematic	O
because	O
early	O
expert	B-Application
systems	I-Application
were	O
built	O
using	O
tools	O
(	O
such	O
as	O
earlier	O
Lisp	B-Language
versions	O
)	O
that	O
interpreted	O
code	O
expressions	O
without	O
first	O
compiling	O
them	O
.	O
</s>
<s>
This	O
provided	O
a	O
powerful	O
development	O
environment	O
,	O
but	O
with	O
the	O
drawback	O
that	O
it	O
was	O
virtually	O
impossible	O
to	O
match	O
the	O
efficiency	O
of	O
the	O
fastest	O
compiled	O
languages	O
(	O
such	O
as	O
C	B-Language
)	O
.	O
</s>
<s>
System	O
and	O
database	O
integration	O
were	O
difficult	O
for	O
early	O
expert	B-Application
systems	I-Application
because	O
the	O
tools	O
were	O
mostly	O
in	O
languages	O
and	O
platforms	O
that	O
were	O
neither	O
familiar	O
to	O
nor	O
welcome	O
in	O
most	O
corporate	O
IT	O
environments	O
–	O
programming	O
languages	O
such	O
as	O
Lisp	B-Language
and	O
Prolog	B-Language
,	O
and	O
hardware	O
platforms	O
such	O
as	O
Lisp	B-Operating_System
machines	I-Operating_System
and	O
personal	O
computers	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
much	O
effort	O
in	O
the	O
later	O
stages	O
of	O
expert	B-Application
system	I-Application
tool	O
development	O
was	O
focused	O
on	O
integrating	O
with	O
legacy	O
environments	O
such	O
as	O
COBOL	B-Application
and	O
large	O
database	O
systems	O
,	O
and	O
on	O
porting	O
to	O
more	O
standard	O
platforms	O
.	O
</s>
<s>
These	O
issues	O
were	O
resolved	O
mainly	O
by	O
the	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
paradigm	O
shift	O
,	O
as	O
PCs	O
were	O
gradually	O
accepted	O
in	O
the	O
IT	O
environment	O
as	O
a	O
legitimate	O
platform	O
for	O
serious	O
business	O
system	O
development	O
and	O
as	O
affordable	O
minicomputer	B-Architecture
servers	O
provided	O
the	O
processing	O
power	O
needed	O
for	O
AI	B-Application
applications	O
.	O
</s>
<s>
Another	O
major	O
challenge	O
of	O
expert	B-Application
systems	I-Application
emerges	O
when	O
the	O
size	O
of	O
the	O
knowledge	O
base	O
increases	O
.	O
</s>
<s>
For	O
instance	O
,	O
when	O
an	O
expert	B-Application
system	I-Application
with	O
100	O
million	O
rules	O
was	O
envisioned	O
as	O
the	O
ultimate	O
expert	B-Application
system	I-Application
,	O
it	O
became	O
obvious	O
that	O
such	O
system	O
would	O
be	O
too	O
complex	O
and	O
it	O
would	O
face	O
too	O
many	O
computational	O
problems	O
.	O
</s>
<s>
This	O
is	O
a	O
well-known	O
NP-complete	O
problem	O
Boolean	B-Algorithm
satisfiability	I-Algorithm
problem	I-Algorithm
.	O
</s>
<s>
Other	O
problems	O
are	O
related	O
to	O
the	O
overfitting	B-Error_Name
and	O
overgeneralization	O
effects	O
when	O
using	O
known	O
facts	O
and	O
trying	O
to	O
generalize	O
to	O
other	O
cases	O
not	O
described	O
explicitly	O
in	O
the	O
knowledge	O
base	O
.	O
</s>
<s>
Because	O
of	O
the	O
above	O
challenges	O
,	O
it	O
became	O
clear	O
that	O
new	O
approaches	O
to	O
AI	B-Application
were	O
required	O
instead	O
of	O
rule-based	O
technologies	O
.	O
</s>
<s>
The	O
key	O
challenges	O
that	O
expert	B-Application
systems	I-Application
in	O
medicine	O
(	O
if	O
one	O
considers	O
computer-aided	O
diagnostic	O
systems	O
as	O
modern	O
expert	B-Application
systems	I-Application
)	O
,	O
and	O
perhaps	O
in	O
other	O
application	O
domains	O
,	O
include	O
issues	O
related	O
to	O
aspects	O
such	O
as	O
:	O
big	B-Application
data	I-Application
,	O
existing	O
regulations	O
,	O
healthcare	O
practice	O
,	O
various	O
algorithmic	O
issues	O
,	O
and	O
system	O
assessment	O
.	O
</s>
<s>
Finally	O
,	O
the	O
following	O
disadvantages	O
of	O
using	O
expert	B-Application
systems	I-Application
can	O
be	O
summarized	O
:	O
</s>
<s>
Expert	B-Application
systems	I-Application
have	O
superficial	O
knowledge	O
,	O
and	O
a	O
simple	O
task	O
can	O
potentially	O
become	O
computationally	O
expensive	O
.	O
</s>
<s>
Expert	B-Application
systems	I-Application
require	O
knowledge	O
engineers	O
to	O
input	O
the	O
data	O
,	O
data	O
acquisition	O
is	O
very	O
hard	O
.	O
</s>
<s>
The	O
expert	B-Application
system	I-Application
may	O
choose	O
the	O
most	O
inappropriate	O
method	O
for	O
solving	O
a	O
particular	O
problem	O
.	O
</s>
<s>
Problems	O
of	O
ethics	O
in	O
the	O
use	O
of	O
any	O
form	O
of	O
AI	B-Application
are	O
very	O
relevant	O
at	O
present	O
.	O
</s>
<s>
Hayes-Roth	O
divides	O
expert	B-Application
systems	I-Application
applications	O
into	O
10	O
categories	O
illustrated	O
in	O
the	O
following	O
table	O
.	O
</s>
<s>
Also	O
,	O
while	O
these	O
categories	O
provide	O
an	O
intuitive	O
framework	O
to	O
describe	O
the	O
space	O
of	O
expert	B-Application
systems	I-Application
applications	O
,	O
they	O
are	O
not	O
rigid	O
categories	O
,	O
and	O
in	O
some	O
cases	O
an	O
application	O
may	O
show	O
traits	O
of	O
more	O
than	O
one	O
category	O
.	O
</s>
<s>
Hearsay	O
was	O
an	O
early	O
attempt	O
at	O
solving	O
voice	B-Application
recognition	I-Application
through	O
an	O
expert	B-Application
systems	I-Application
approach	O
.	O
</s>
<s>
For	O
the	O
most	O
part	O
this	O
category	O
of	O
expert	B-Application
systems	I-Application
was	O
not	O
all	O
that	O
successful	O
.	O
</s>
<s>
These	O
kinds	O
of	O
systems	O
proved	O
much	O
more	O
amenable	O
to	O
a	O
neural	B-Architecture
network	I-Architecture
AI	B-Application
solution	O
than	O
a	O
rule-based	O
approach	O
.	O
</s>
<s>
The	O
general	O
problem	O
it	O
solved	O
—	O
designing	O
a	O
solution	O
given	O
a	O
set	O
of	O
constraints	O
—	O
was	O
one	O
of	O
the	O
most	O
successful	O
areas	O
for	O
early	O
expert	B-Application
systems	I-Application
applied	O
to	O
business	O
domains	O
such	O
as	O
salespeople	O
configuring	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
VAX	B-Device
computers	O
and	O
mortgage	O
loan	O
application	O
development	O
.	O
</s>
<s>
SMH.PAL	O
is	O
an	O
expert	B-Application
system	I-Application
for	O
the	O
assessment	O
of	O
students	O
with	O
multiple	O
disabilities	O
.	O
</s>
<s>
GARVAN-ES1	O
was	O
a	O
medical	O
expert	B-Application
system	I-Application
,	O
developed	O
at	O
the	O
Garvan	O
Institute	O
of	O
Medical	O
Research	O
,	O
that	O
provided	O
automated	O
clinical	O
diagnostic	O
comments	O
on	O
endocrine	O
reports	O
from	O
a	O
pathology	O
laboratory	O
.	O
</s>
<s>
It	O
was	O
one	O
of	O
the	O
first	O
medical	O
expert	B-Application
systems	I-Application
to	O
go	O
into	O
routine	O
clinical	O
use	O
internationally	O
and	O
the	O
first	O
expert	B-Application
system	I-Application
to	O
be	O
used	O
for	O
diagnosis	O
daily	O
in	O
Australia	O
.	O
</s>
<s>
The	O
system	O
was	O
written	O
in	O
"	O
C	B-Language
"	O
and	O
ran	O
on	O
a	O
PDP-11	O
in	O
64K	O
of	O
memory	O
.	O
</s>
<s>
Mistral	O
is	O
an	O
expert	B-Application
system	I-Application
to	O
monitor	O
dam	O
safety	O
,	O
developed	O
in	O
the	O
1990s	O
by	O
Ismes	O
(	O
Italy	O
)	O
.	O
</s>
