Knowledge Acquisition in the Fuzzy Knowledge

Representation Framework of a Medical Consultation System

By: Karl Boegl, Klaus-Peter Adlassnig, Yoichi Hayashi, Thomas Rothenfluh, and Harald Leitich

MedFrame/CADIAG-IV

- The predecessor: CADIAG-II - Consultation System- New Implementation- Generalized Domain Model- Fuzzy Dice

Definitions

Fuzzy Set Theory Fuzzy Logic Fuzzy Control

Rule-Based Fuzzy Logic System

• Rules

• antecedent

• consequent

• Fuzzifier

• inference engine

• output processor

Fuzzy Logic Example

tall(x) = { 0, if height(x) < 5 ft.,(height(x)-5ft.)/2ft., if 5 ft. <= height (x) <= 7 ft.,

1, if height(x) > 7 ft. }

Membership Function

1.0 + +-------------------

| /

| /

0.5 + /

| /

| /

0.0 +-------------+-----+-------------------

| |

5.0 7.0

height, ft. ->

Person Height degree of tallness

--------------------------------------

Billy 3' 2" 0.00

Yoke 5' 5" 0.21

Drew 5' 9" 0.38

Erik 5' 10" 0.42

Mark 6' 1" 0.54

Kareem 7' 2" 1.00

Logic Operations in Fuzzy Logic

truth (not x) = 1.0 - truth (x)

truth (x and y) = minimum (truth(x), truth(y))

truth (x or y) = maximum (truth(x), truth(y))

Another Example

old (x) = { 0, if age(x) < 18 yr.

(age(x)-18 yr.)/42 yr., if 18 yr. <= age(x) <= 60 yr. 1, if age(x) > 60 yr. }

a = X is TALL and X is OLD

b = X is TALL or X is OLD

c = not (X is TALL)

height age X is TALL X is OLD a b c

------------------------------------------------------------------------

3' 2" 65 0.00 1.00 0.00 1.00 1.00

5' 5" 30 0.21 0.29 0.21 0.29 0.79

5' 9" 27 0.38 0.21 0.21 0.38 0.62

5' 10" 32 0.42 0.33 0.33 0.42 0.58

6' 1" 31 0.54 0.31 0.31 0.54 0.46

7' 2" 45 1.00 0.64 0.64 1.00 0.00

3' 4" 4 0.00 0.00 0.00 0.00 1.00

Representation within MedFrame/CADIAG-IV

Positive Associations FP Consequent => Antecedent

SP Antecedent => Consequent

Negative Associations FN -(Consequent) => Antecedent

SN Antecedent => -(Consequent)

Knowledge Refinements (1 of 2)

Knowledge Refinements (2 of 2)

Project Successes

References Title: Knowledge Acquisition in the Fuzzy Knowledge Representation Framework

of a Medical Consultation System By: Karl Boegl, Klaus-Peter Adlassnig, Yoichi Hayashi, Thomas Rothenfluh, Harald Leitich Copyright: 2001

Title: The MedFrame Project http://medexpert.imc.akh-wien.ac.at/MedFrame/

By: Dieter KopeckyCopyright: 2000

Title: Medical Expert Systems http://www.computer.privateweb.at/judith/name_3.htm

By: Judith FederhoferCopyright: 2002

(More)

References (continued)

Title: Systematized Nomenclature of Medicine

http://www.snomed.org

By: College of American Pathologists

Copyright: 2001-2003

http://www-2.cs.cmu.edu/Groups/AI/html/faqs/ai/fuzzy/part1/faq/html Mendel, Jerry. “Uncertainty in Fuzzy Logic Systems.” University of

Southern California.