2. OUTLINE HISTORY MYCIN : The Problem System Components Expert
System Structure STAGES: in Diagnosis and Treatment MYCIN
Architecture Explanation Summary 3. HISTORY MYCIN was developed at
StanfordUniversity in the mid 1970s. Project spans a decadeResearch
started in 1972. Original Implementation completed in 1976.
Research continued into the 1980s. 4. MYCIN : The Problem Roberts
& Visconti [1972]: Only 13% of patients are treated. 66% are
being irrational treatment.21% are being questionable treatment.
Irrationality means, for example : Using a contraindicated
combination. Using the wrong agent for a specific organism. Not
taking the required cultures. 5. Design Parameter Program must be
competent and easyto use. Must handle a large changing body of
knowledge. Interact with human users. Must take time into account.
Work with incomplete and uncertain information. 6. SYSTEM
COMPONENTS Consultation System ask question. Draws conclusions.
Given advice . Explanation System Translation ruler Rule
Acquisition / Modification System 7. Expert System Structure
Knowledge BaseUser InterfaceInference Engine Explanation
FacilityBlackboard Language/Shell Environment 8. Stages in
Diagnosis and Treatment Decide if there is any significant
infection. Identify the causing organism by clinical andlaboratory
evidence. Decide what antibiotics agent the organism are sensitive
too. Prescribe the optimal drug combinations for the particular
care. 9. MYCIN ARCHITECTURE Consultation ProgramDynamic Patient
DataExplanation ProgramKnowledge Acquisition Program Infectious
Diseases ExpertPhysician user Static Factual & Judgemental
Knowledge 10. Consultation System Consultation System Has Performs
Diagnosis and Therapy Selection Control Structure reads Static DB
(rules) and read/writes to Dynamic DB (patient/ context). Linked to
Explanation Terminal interface to Physician. 11. Explanation System
Provides reasoning why a conclusion has beenmade , or why a
question is being asked. Record rule invocation and associates them
with questions and rules invoked. Use rule index to retrieve
particular rules in answer to question . Why and how questions are
answered using goal tree. 12. Knowledge Acquisition Program Extend
static DB via Dialogue with experts Dialogue driven by Experts
Requires minimal training for Experts. Allows for Incremental
Competence , NOT anALL or- Nothing model. IF-THEN symbolic logic
was found to be easy for Experts to learn, and required little
training by the MYCIN training. 13. SUMMARY MYCIN combines the
advantages of general rulebased system with the advantages of an
inexact reasoning. MYCIN has not addressed how to convert fromhuman
terms to certainties how to normalize across different peoples how
far to propagate certainty factor changes based on new evidences
how to provide feedback to database to improve certainty factor
accuracy. 14. THANK YOU
