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CS 331/531 Dr M M Awais 2
RBS
“Classic” systems Pre-1980s Systems showed how to
capture heuristic knowledge and store it; make a software that could mimic advice
dispensation like expert human do. Techniques that were implemented were used
in many subsequent systems, Many expert system shells were developed.
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Expert systems MACSYMA
advised the user on how to solve complex maths problems.
DENDRAL advised the user on how to interpret the
output from a mass spectrograph MYCIN PROSPECTOR R1/XCON
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Others
CENTAUR INTERNIST PUFF CASNET DELTA - locomotive engineering Drilling Advisor - oilfield prospecting ExperTax - tax minimisation advice XSEL - computer sales
All medical expert systems
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Task Classification
Various tasks could be performed A layout presented by Hayes-Roth
& colleagues in 1983 is presented here
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Diagnosis
finding faults in a system, or diseases in a living system
MYCIN - diagnosed blood infection. Shortliffe, 1976.
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Interpretation
The analysis of data, to determine their meaning
PROSPECTOR - interpreted geological data as potential evidence for mineral deposits. Duda, Hart, et al 1976.
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Monitoring
The continuous interpretation of signals from a system for avoiding dangerous situations
NAVEX - monitored radar data and estimated the velocity and position of the space shuttle. Marsh, 1984
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Design
To ensure production of specifications, satisfying particular requirements
R1/XCON - configured VAX computer systems on the basis of customers' needs. McDermott, 1980.
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Planning
Production of a sequence of actions that will achieve a particular goal.
MOLGEN - planned chemical processes whose purpose was to analyse and synthesise DNA. Stefik, 1981.
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Instruction: Intelligent Tutoring Systems
Teaching a student a body of knowledge, varying the teaching according to assessments
SOPHIE - instructed the student on the repair of an electronic power-pack. Brown, Burton & de Kleer, 1982.
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Prediction
Forecasting future events, using a model based on past events.
PLANT - predicted the damage to be expected when a corn crop was invaded by black cutworm. Boulanger, 1983.
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Debugging & repair
Generating, administering remedies for system faults.
COOKER ADVISER - provides repair advice with respect to canned soup sterilising machines. Texas Instruments, 1986.
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Controls
Governing the behaviour of a system by anticipating problems, planning solutions, and monitoring actions.
VENTILATOR MANAGEMENT ASSISTANT - scrutinised the data from hospital breathing-support machines, and provided accounts of the patients' conditions. Fagan, 1978.
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MYCIN: Diagnosis System
Domain: diagnose blood infections of the sort that might be contracted in hospital
Developed by: Edward Shortliffe and colleagues, 1972 to late 1970s.
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MYCIN
Purpose: to assist a physician, who was not an expert in the field of antibiotics, with the diagnosis & treatment of blood disorders (and in particular to establish whether the patient was suffering from a serious infection like meningitis).
Input: symptoms & test results Output: a diagnosis, accompanied by a
degree of certainty, & recommended therapy
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MYCIN Knowledge representation:
production rules
Inference engine: Mixed chaining, but principally backward chaining from a top goal
Dealing with uncertainty: By calculating certainty factors.
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MYCIN A Complete system that did complex task.
Performed better than medical students and non-specialist doctors.
Performed equally good to blood infection specialist doctors
MYCIN was a laboratory demonstration only Was never commercialised, was never marketed,
or installed in a hospital and used for routine work.
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MYCIN Description of the system.
Written in LISP. MYCIN was a mixed-chaining
production system.
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MYCIN The sequence of operations was that
the system asked: Questions to get general details about
the patient (name, age, sex, race, clinical test results already known).
Questions designed to find a possible, general diagnosis (e.g. the patient has probably got some form of meningitis), by forward chaining.
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MYCIN Questions designed to test this
theory, and establish specific details, by backward chaining. This was where most of the reasoning was done.
Questions designed to produce a recommended treatment, again by forward chaining.
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MYCIN MYCIN could explain its reasoning in a
rather simple way: when asked "Why do you think that is
the diagnosis?”, MYCIN listed the rules it had applied, in reverse order, with CFs.
When asked "Why do you want to know that?", MYCIN described the rule it was trying to execute, and what value it was trying to find.
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MYCINA Consultation with MYCIN@ mycinMYCIN 26-MarchInstructions? (Y or N) N26-March 10:42-----PATIENT-1-----Patient's name: Yousaf
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Consultation with MYCINAge? 34Sex? Why [i.e. Why is it important to
determine the sex of PATIENT-1?]The sex of the patient is one of the
four standard parameters that identify a patient. This may be useful later.
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Consultation with MYCINSex? MaleRace? Sindhi
Are there any cultures for Yousaf that may be related to the present illness, and from which organisms have been grown successfully in the lab?
No
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Consultation with MYCIN
Are there any pending cultures for Yousaf?
Yes-----CULTURE-1-----From what site was the specimen for CULTURE-1 taken?
Cerebro Spinal FluidPlease give the date and time when the pending CSF culture was obtained.
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Consultation with MYCIN 26-March-7:00
Was a smear examined at the time the specimen was obtained?
YesWere there any cultures seen on the smear of the specimen?
NoAre there any other pending cultures?
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Consultation with MYCIN
NoHas Yousaf recently had symptoms of
persistent headache or other abnormal neurological symptoms (dizziness, lethargy, etc)?
YesHas Yousaf recently had objective
evidence of abnormal neurological signs (nuchal rigidity, coma, seizures, etc) documented by a physician?
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A Consultation with MYCIN YesThe CSF cultures will be considered
to be associated with MENINGITIS.Please give the date on which clinical
evidence (symptoms, signs, or laboratory tests) of the meningitis first appeared.
25 March 10:00Has Yousaf had neurosurgery?
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A Consultation with MYCIN Why [i.e. WHY is it important to
determine whether PATIENT-1 has had neurosurgery?]
This will aid in determining the organisms (other than those seen on cultures or smears) that might be causing the infection.
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A Consultation with MYCINIt has already been established that
[1] the culture that requires therapy is meningitis, and
[2] organisms were not seen on the stain of the pending csf culture (CULTURE-1), and
[3] the type of infection is bacterial
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A Consultation with MYCIN
Therefore, if [4] Yousaf has had neurosurgery, and [5] the time since the neurosurgical operation is
less than two months, and [6] the type of neurosurgery is not ventricular-
urethal shunt
then there is evidence that the organisms that might
be causing the infection are staphylococcus-coag-pos (0.75), staphylococcus-coag-neg (.5), e.coli (.4), klebsiella (0.3)
Author: Yu [RULE511]
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A Consultation with MYCIN
Has Yousaf had neurosurgery? How [3] [i.e. HOW was it established
that the type of infection is bacterial?]
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A Consultation with MYCIN
The following rules concluded about the likelihood that the type of infection is bacterial:
Rule Yes No500 (.4)501 (.17)502 (.1)524 (.42)504 (.28)Thus it has been established that the
type of infection might be bacterial.
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A Consultation with MYCIN
Has Yousaf had neurosurgery? NoIs Yousaf a burn patient? Yes
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A Consultation with MYCIN
I have found evidence (RULE507) that treatment should cover for Diplococcus pneumoniae causing meningitis.
I have found evidence (RULE545) that treatment should cover for e.coli causing meningitis.
I have found evidence (RULE545 RULE578) that treatment should cover for Pseudomonas aeruginosa causing meningitis.
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A Consultation with MYCIN
Does Yousaf have focal neurological signs?
No[Determining which dosages are
desirable for use against the e.coli...]
[Determining which drugs are desirable for use ...]
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A Consultation with MYCININFECTION-1 is MENINGITIS+ <ITEM-1> DIPLOCOCCUS-
PNEUMONIAE (from clinical evidence only)
+ <ITEM-2> E.COLI (from clinical evidence only)
+ <ITEM-3> PSEUDOMONAS AERUGINOSA (from clinical evidence only)
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A Consultation with MYCIN
[REC-1] My preferred therapy recommendation is as follows:
In order to cover for items <1 2 3>:Give the following in combination:1) AMPICILLIN
Dose: 3.85g(30.8ml) q4h IV
2) GENTAMICINDose: 131mg(3.2ml) q8h IV
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A Consultation with MYCIN
Comments: monitor serum concentrations.Since high concentrations of penicillins can inactivate aminoglycosides, do not mix these antibiotics in the same IV bottle.
Do you wish to see the next choice therapy?
No
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CROP ADVISOR
Developed by ICI (in 1989) to advise cereal grain farmers on appropriate fertilisers and pesticides for their farms.
The choice of chemical, amount, and time of application depends on such factors as crop to be grown, previous cropping, soil condition, acidity of soil, and weather.
Farmers can access the system via the internet.
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CROP ADVISOR Given relevant data, the system
produces various financial return projections for different application rates of different chemicals.
The system uses statistical reasoning to come to these conclusions.
If the question asked is outside the system's expertise, it refers the caller to a human expert.
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CROP ADVISOR The chief advantages of this system
have been that employees at ICI have been
relieved of the need to provide lengthy telephone advice sessions,
and the quality of the advice has become much more uniform, which has increased confidence in the company's products.
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R1/XCON
Knowledge domain: Configuring VAX computers, to customers' specifications.
Written by: John McDermott and colleagues, 1978 - 1981
Input: Required characteristics of the computer system.
Output: Specification for the computer system.
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R1/XCON Knowledge representation:
Production rules. Inference engine: Forward chaining:
the output specification was assembled in working memory.
Dealing with uncertainty: No mechanism for this: the system simply assembled one answer, assumed to be good enough to do the job.
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R1/XCON Significance:
A rather simple forward-chaining rule-based expert system, which performed well, solved a difficult manufacturing problem, and proved to be enormously profitable.
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that they were marketing the best-selling Vax-11 series of computers, and the department responsible for configuration was failing to keep up with customer demand.
Each computer was the result of a consultation between a sales executive and the customer, designed to discover the customer's requirements, after which a configuration was drawn up, from which the system was built.
Each configuration was taking 25 minutes, and orders were arriving at a rate of 10,000 a year.
High error rate in the configurations was recorded.
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R1/XCON
DEC tried a conventional program to solve this problem, with no success, then asked McDermott to write an AI system.
McDermott wrote R1/XCON. By 1986, it had processed 80,000 orders,
and achieved 95-98% accuracy. It was reckoned to be saving DEC $25M a
year.
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R1/XCON However, R1/XCON suffered from the
shortcomings of simple production-rule-based systems. When the nature of the task changed,
fresh rules were simply added at the end of the rulebase.
Soon, the rulebase was very large, unreliable and incomprehensible.
Expensive rewriting was needed to restore the operation of the system.
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OPTIMUM-AIV
OPTIMUM-AIV is a planner used by the European Space Agency (1994) to help in the assembly, integration, and verification of spacecraft.
It generates plans, and monitors their execution.
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OPTIMUM-AIV it has a knowledgebase that describes
the causal links that describe that in what particular order the assembly must be undertaken.
Also, if a plan fails and has to be repaired, the system can make intelligent decisions about the alternative plans that will work and will not.
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OPTIMUM-AIV It can engage in hierarchical planning
- this involves producing a top-level plan with very little detail, and then turning this into increasingly more detailed lower-level plans.
It can reason about complex conditions, time, and resources (such as budget constraints).