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Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

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Page 1: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Fuzzy inference

20 26

Warm

17

Cold Hot

29

50

Partial

30

Cloudy Sunny

100

Fuzzyfication Implication

48

MediumLow High

Defuzzyfication

Page 2: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Knowledge base: defines rules and membership functions

Defuzzyfier: translates fuzzy outputs into crisp values

Fuzzyfier: translates crisp inputs into fuzzy values

Inference engine: applies reasoning to compute fuzzy outputs

DefuzzifierInferenceEngine

Fuzzifier

Rule base

Database

Knowledge base

FuzzyOutputFuzzy Output

CrispInputCrisp

Input

..

.. Logic Systems Laboratory − Swiss Federal Institute of Technology

Carlos Andres Pena Reyes

Fuzzy inference systems

Page 3: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Gas

LowOR

Pressure

Temp.

&

&

&

High

Hot

Cold

Low

ORHigh

.

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

.

Carlos Andrés Peña−Reyes

. .

Network−like view of a fuzzy system

Page 4: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Membership function values

Gas

OR

Hot

Cold

Low

High

Pressure

Temp.

&

Low

&

&

HighOR

. .Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

.

Operational parameters.

Page 5: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

RulesConsequents

Weights

Gas

Pressure

Temp.

Antecedents

Low

OR

Hot

Cold

High

&

&

&

High

LowOR

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

.

.

Connective parameters

.

.

Page 6: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Low

{ Membership functionsRulesRelevant variables

Pressure

Temp.

Number of

OR

Hot

Cold

High

Low

Gas

High

&

&

OR

&

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

. .

. .

Structural parameters

Page 7: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Pressure

Defuzzification methodMembership function typesFuzzy operatorsReasoning mechanism&

&

&

Temp.

Low

High

OR

ORGas

Low

Hot

Cold

High

.

.

. Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

.

Logical parameters

Page 8: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Parameters of a fuzzy system

Relevant variables

Number of membership functions

Number of rules

Consequents of rules

Defuzzification method

Antecedents of rules

Operational

Connection

Fuzzy operatorsLogic

Class

Membership function types

Membership function values

Rule weights

Structural

Database

Rulebase

Knowledge base

Defuzzifier

Fuzzi- and defuzzifier

Inference engine

ComponentParameters

..

..

Carlos Andrés Peña-Reyes

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

Reasoning mechanism

Page 9: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

If Tempearture is WARM then Ventilator is Low

If Temperature is HOT then Ventilator is Medium

InterpretabilityPrecision

Linguistic

... Let’s go to the lake!!!

If Temperature is VERY−HOT then Ventilator is High

If Temperature is HELLISH then Ventilator is Off, and...

If Temperature is COOL then Ventilator is Off

Numeric

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

.

Dual external nature

. .

.

Page 10: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Universal approximator

Numeric mapping: Crisp inputs / Crisp outputs

Uncertainty management: noise and low quality of data

Nonlinear behavior, but linearity not excluded

.

..

Carlos Andrés Peña-Reyes

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

.

Numeric issues

Page 11: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Number of elements: Compatible with human capabilities

Distinguishability: Each linguistic label has semantic meaning

Coverage: Any element belongs to at least one fuzzy set

Normalization: At least one element has unitary membership

Complementarity: For each element, the sum of memberships is one

Semantics: the study of meanings

0

1Cold Cool Warm

Temperature

Hot

0

1Cold

Temperature

HotCool Warm

..

.. Logic Systems Laboratory − Swiss Federal Institute of Technology

Carlos Andres Pena Reyes

Interpretability considerations: semantic criteria

Page 12: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Consistency: rules firing simultaneously must have similar consequents

Rule readability: small number of conditions in rule antecedents

Rule−base simplicity: Set of rules as small as possible

Completeness: for any input, at least one rule must fire●

Syntax: the way in which linguistic elements are put together

5R

0RR2

R

R

1R

R A

7R 9R

5

R

4R 6RR

1R 3R2R

RAR4

RB B

5

8

.

.. Logic Systems Laboratory − Swiss Federal Institute of Technology

Carlos Andres Pena Reyes

Interpretability considerations: syntactic criteria.

Page 13: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Linguistic labels shared by all rules

Normal, orthogonal membership functions

Default rule

Don’t care conditions

5 R

0R

A

RB

R

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology. .

. .

17 20 26 29

Cold Warm Hot

Strategies to satisfy interpretability criteria

Page 14: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

What do you know about the modeled system?

Have you preferences or restrictions to the model?

How do you search?

Search methodi.e. do a well suited and/or well known technique exists?

i.e. what is predefined and what looked for?Search space

Constraintsi.e. do issues like size, speed, or simplicity matter?

..

..

The general modeling problem

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Page 15: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Database

Rule base

InferenceEngine Defuzzifier

some parameter pre−definition is thus required.The number of parameters is too high to perform a full search,

and, or, not, ...

f1, ... , fm

P1 P2 P3 P4

R1, ... , Rn

If V1 is Low AND ....

According with the searched parameters we can have:

System design.

Structural parameters:

Behavior learning.Connective parameters:

Operational parameters:

Logical parameters:

Knowledge tuning.

Structure learning.

..

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Knowledge base

Fuzzifier

. .

Search space in fuzzy modeling

Page 16: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

"Classic" identification methods

Knowledge engineering

Evolutionary fuzzy modeling techniques

Neuro−fuzzy systems

Machine learning approaches

.

..

.

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

Search methods: Fuzzy modeling techniques

Page 17: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

− Diagnostic: Overall performance, sensitivity, specificity

− Data mining: Completness, complexity.

− Availability: Continuity of explanations (time to provide them)− Interpretability: Allowed complexity.

Who is going to interact with the system?

− Control: Dynamic response, adaptability, robustness, etc.

− Speed: Real−time constraints, computing resources.

− Size: Available memory, computing platform.

− Classification: Classification performance, quadratic error.

What is the fuzzy system expected to do?

How is the system expected to do it?

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

.

Usual constraints in fuzzy modeling

. .

.

Page 18: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

all rules share the same MFs

null and unity membership

Rule−specific MFs are not allowed

Orthogonal MFs with well defined

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

.

. .

.

Interpretability−related constraints

Page 19: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Fuzzy modeling: direct approach

This approach is also called knowledge engineering

Domainexpert

Knowledgeengineer

Fuzzymodel

Design loop

Validation loop

Page 20: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Domain expert

Fuzzy modeling: data-driven approaches

This approaches are also denominatedknowledge discovering

Fuzzymodel

Design loop

Validation loop

Domain data Building algorithm

Page 21: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Neuro−fuzzy systems

Fuzzy system

Identification−based

Constructive−learningFuzzy system

Fuzzy system

DataOperational

Connective

Structural

Structural

Connective

Logicdesign

algorithmEstimation

Operational

ANN−like training algorithm

Human

. .

. .

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology

Fuzzy modeling: some data−driven approaches

Page 22: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

- Genome encodes values P, Q, and C

- Knowledge is tuned by evolution,

which searches for membership function values

- Rules of type:

if X1=Low and X2=Normal then Output = Ci

- Fixed rule base (completness)X2

X1

R9

R8R5

R4

R6

R7

R3

R1

R2

P3P2P1

Q2

Low Mid High

Q3

Big

Nor

mal

Sm

all

Q1

(3*P + 3*Q + 9*C) * 5 bits = 75 bits

..

..

Carlos Andrés Peña-Reyes

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

Evolutionary knowledge tuning (database)

Page 23: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Don’t care conditions and default rule

- Three main approches to evolutionary behavior learning

- Evolution can be used to find a minimal (or fixed size) rule base,

(i.e. fuzzy system)

- Two strategies for reducing this number:

- Number of rules exploses rapidly

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

RiR3

R2

Ra, Rb, Rc ...

R1

Iterative Rule Learning

Incremental construction ofthe knowledge base

Evolution finds the best rule

Carlos Andrés Peña-Reyes

R1

Michigan

Individual = One rule

Population = Rule base

.

R2

Pittsburgh

(rule base or knowledge base)Individual = Entire system

Population of systems

.

.

Ri

Evolutionary behavior learning (rule base)

R3

.

Page 24: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

- Genome encodes rules: Antecedents and consecuents

- Evolution searches for a subset of N rules (fixed by the designer)

5 functions + 3 don’t care

- Space of 625 rules (1295 including don’t care conditions)

- 4 input variables, 5 membership functions per variable{Tiny, Small, Normal, Big, Huge}

IF V1 is Tiny AND ... AND V4 is Normal then Out = Huge

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

R2 .... Ri

Carlos Andrés Peña-Reyes

RnR1 ....

5 * 3 bits

15 bits

N rules * 15 bits

A1 A3 CA4A2

Evolutionary behavior learning: An example

. .

. .

Page 25: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Behavior learning

Evolutionary knowledge base learning

attributeFuzzy systemType of

valuesquantityUsual

type

Operational

Connective

class

Knowledge tuning 10 - 1000 Real-valued Database

Modeling

Symbolic Rule base10 - 1000

Parameter

- Computation requirements

- Parameter representation

- Size of the search space

- Tight interdependency

(Knowledge base = rule base + database)

Critical issues for applying evolution:

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña-Reyes

. .

. .

Page 26: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Evolutionary knowledge base learning

Sample ru;e: IF V1 is Low and V4 is High THEN Diagnostic is Benign

- A basic approach: Single population, single evolution

Example: Breast cancer diagnosis problem (Peña and Sipper 99)

- Genome encodes: Rule antecedents and membership function parameters

- A simple genetic algorithm searches for the knowledge base

- 9 inputs, 1 output, 2 membership functions per variable

Ai A9....A1 ....

9 antecedents * 2 bits

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

18 bits

P d

Carlos Andrés Peña-Reyes

3 bits 3 bits

....

6 bits

.... Ri .... RnV1 V2 Vi .... V9

.

9 Variables * 6 bits Nr rules * 18 bits

Low

dP

High

.

R2R1

.

.

Page 27: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Evolutionary knowledge base learning

1

Symbolic part: Rule baseNumeric part: Database

- A variation: Single population, double evolution

- The rule base is evolved using genetic programming

Example: Evolving fuzzy rule based classifiers with GA–P (García et al. 99)

- Genome encodes: Complete rule base and membership function parameters

- A simple genetic algorithm searches for the database

00 0 1 0 0 0 1 1 0

.. Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

. .

Carlos Andrés Peña-Reyes

Page 28: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

X1

X2

Evolutionary knowledge base learning

Q3

Sm

all

Q1

Big

Low Mid High

Q2

Nor

mal R2

A fuzzy self-organizing map searches for P and Q values

Genome encodes rules: Antecedents and consequent

(J.-F. Philagor, student project SPG, 1999)Example: Breast cancer diagnosis- Evolution searches for a fixed-size rule base

- Hybrid learning: Evolved rule base, learned database

P1 P2 P3

R3R1

- Database is tuned using a neuro-fuzzy approach

R1 R2

.

Ri .... Rn....

A1 CA2 A9. . .

9 * 2 bits + 1 bit

19 bits

N rules * 19 bits

. .

.

Carlos Andrés Peña-Reyes

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

Page 29: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

..

. .

The

test

Carlos Andrés Peña-Reyes

The

feat

ures

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

The

dat

abas

e

The Wisconsin Breast Cancer Database

Page 30: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

.

. .

Carlos Andrés Peña-Reyes

... ...

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne... ...

else (Output is Malignant)

R1: if (V1 is Low) and (V2 is High) and ... and (V9 is Low) then (output is Benign)R2: if (V1 is Low) and (V2 is Low) and ... and (V9 is None) then (output is Benign)

...Malignant

P1+d1P1 P P2 +d +dP P2 2 9 9

.

9

Low

High

Low

LowLow

None

.....

.....

Benign

Benign

VV V1 2 9

Proposed Fuzzy System

Page 31: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

.

.

.

Carlos Andrés Peña-Reyes

Ai = 0 or 3 (Variable not assigned)d = [1;8]

P = [1;8]

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

Ai = 1 (Benign)

d

Ai = 2 (Malignant)

.

3 bits 3 bits

P Ai A9....A1 ....

.... R1 R2 .... Ri .... RnV1 V2 Vi .... V9

9 antecedents * 2 bits

9 Variables * 6 bits Nr rules * 18 bits

6 bits 18 bits

Total genome length = 54 + 18Nr bits

Genome encoding

cs bgu
cs bgu
cs bgu
Page 32: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Fv : Number of variables

selection pressure to fine tune parameters

measures the interpretability

the most important performance measure

Fe : Quadratic error

Fc : Classification performance,

F = Fc + a* Fv + b*Fe

Carlos Andrés Peña-Reyes

.

. Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne .

.

Fitness function

Page 33: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

97.36% (3)

97.80% (4.8)

97.80% (4.7)

97.07% (4)

96.65% (7)

96.35% (3)

Learned Boolean rules Evolved fuzzy rules

97.51% (3.4)

1

2

3

5

4

96.19% (1.8)

Setiono Tahawork (99)

97.21% (4)97.14% (4)

95.42% (2)

Results: Classification performance (Number of variables)

RulesPeña

Setiono (96) Liu (96)This

Sipper (98)Ghosh (97)

.

.

.

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña-Reyes

.

Page 34: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

IF the clump of cells is not very thick,

ELSE the case is malignant.

THEN the case is benign;

AND nucleoli are not highly abnormal,

AND there are few bare nuclei,

AND the cell’s size is quite uniform,

The best single-rule system

Carlos Andrés Peña-Reyes

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne

Benign

Malignant

v1 v2

Low

v6

Low

v8

Low

. .

.

Low

.

Page 35: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

2 Cooperative coevolutionA building algorithm:

1 Fuzzy systemsA system model:

Fuzzy

CoCo

Database

. .

. .

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology

Proposed approach: two elements

Page 36: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

represented by different types of values,they can be decomposed in distinct components,

and which are very interdependent.

fuzzy modeling an These features render

COOPERATIVEadequate target for

COEVOLUTION

3 − 10Logical

The required solutions can be very complex,

Real−valued10 − 1000Knowledge tuningOperational (labels)

System design

Symbolic10 − 1000Behavior learningConnective (rules)

Integer5 − 20Structure learningStructural (size)

classParameter

typeModeling

numberUsual Type of

values

. .

. .

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology

Fuzzy modeling: a coevolvable problem

Page 37: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

− Better search power− Lesser computational cost− More−flexible setup

Two evolutionary algorithmssearching for:

membership functions

and rules.

Advantages:− Divide−and−conquer strategy

Modification Modification

Selection

EvaluationEvaluation

Selection

Membership functions Rules

.

. .

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

.

Fuzzy CoCo:A cooperative coevolutionary approach to fuzzy modeling

Page 38: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

to form fuzzy systems.2. Individuals are combined with cooperators

individual fitness is then calculated.3. These fuzzy systems are evaluated, and

both fitness−dependent andare selected from generation g−1

1. Cooperators for generation g

randomly

Rules

Fitness

Cooperators

Cooperators

Fitness

MFsRules

Gen

erat

ion

g

g−1

Selected cooperators

MFs

.

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

.

Fitness evaluation in Fuzzy CoCo

Page 39: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

● Linguistic fitness: when used, increases selective pressure for interpretability

Normal, orthogonal membership functions: constrained representation

Shared membership functions: reinforced by the existence of a separate species

Default rule: guarantees complete coverage of the input space

Don’t care conditions: encourage shorter rules

R5 RA

R

0

B

R

0

1Cold Cool Warm

Temperature

Hot

..

.. Logic Systems Laboratory − Swiss Federal Institute of Technology

Carlos Andres Pena Reyes

Interpretability strategies in Fuzzy CoCo

Page 40: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

5.9

3.0

3.0150 Virginica

Classes(1) setosa

(3) virginica(2) versicolor

(1) SL Sepal length(2) SW Sepal width(3) PL Petal length(4) PW Petal width

Features

2 Setosa

The

var

iabl

es

5.14.9

1 3.5 Setosa1.41.4

5.1

0.20.2

1.8

Case ClassSL SW PL PW

. Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

.

. .

The

dat

abas

e

Fisher’s Iris Data

Page 41: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

.

..

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

.

Iris: Variable analysis

Page 42: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Iris proposed solution: Controller−type

Class ClassInputSubsystem

Fuzzy Subsystem

FuzzyInput

Fuzzy

CrispOutput

Output

InputCrisp Fuzzifier Defuzzifier

Knowledge base

Rule base

Database

EngineInference

The selection unit approximates it to the nearest class

The fuzzy subsystem estimates a continuous "class" value

estimation

Stair−function

Carlos Andrés Peña−Reyes

. .

.

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

.

Page 43: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

1 2

21

1 2 3

3

3

... ... ...

R1: if (SL is A11) and (SW is A12) and (PL is A13) and (PW is A14) then (output is Class1)

R2: if (SL is A21) and (SW is A22) and (PL is A23) and (PW is A24) then (output is Class2)

Rn: if (SL is An1) and (SW is An2) and (PL is An3) and (PW is An4) then (output is Classn)

else (Output is Class0)

setosa

Logic Systems Laboratory − Swiss Federal Institute of Technology

...

Carlos Andres Pena Reyes

11 P21 P31 P12 P22 P32 P24P14

.

.

...

P

versicolor

.

virginica

High

Low

LowLow

None

.....

.....

Medium

SL SW PW

.

Iris controller−type: Proposed Fuzzy System

Page 44: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

(setosa)

Iris proposed solution: Classifier−type

Threshold SubsystemClassInput

(versicolor)µ

µ

(virginica)µFuzzyInput

Fuzzy

CrispOutput

Output

InputCrisp Fuzzifier Defuzzifier

Knowledge base

Rule base

Database

EngineInference

Fuzzy Subsystem

The selection unit chooses the most active class

value for each classThe fuzzy subsystem estimates a continuous membership

Maximum and

. .

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

..

Page 45: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Yes

No

No

NoYes Yes

Yes Yes

Yes

YesNo YesNo

NoNoNo Yes

No

31 P24P14P

None

21P11P

Carlos Andres Pena Reyes

.Logic Systems Laboratory − Swiss Federal Institute of Technology

Low

.....

.....

versicolor

PW

setosa

.

virginicaversicolorsetosa

virginica

virginica

.

versicolorsetosa

Low

Medium

SL

... ... ... ... ...

R1: if (SL is A11) and ... and (PW is A14) then (setosa is Yes),(versicolor is No),(virginica is No)

R2: if (SL is A21) and ... and (PW is A24) then (setosa is No),(versicolor is Yes),(virginica is Yes)

Rn: if (SL is An1) and ... and (PW is An4) then (setosa is No),(versicolor is No),(virginica is Yes)

else (setosa is No),(versicolor is Yes),(virginica is No)

.

Iris classifier−type: Proposed Fuzzy System

Page 46: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Membership functions Rules (Controller/Classifier)

P

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

3 x 5 bits

P1 P3

55 5

P2

.

SWSL SW

.

.

Genome length = 60 bits

.

PL R1 ... Ri ... Rn Co

....A1 Ci

Nr rules * 19 bits

A4

4 * 2 bits

2/3 bits

2/3 bits

10/11 bits

4 Variables * 15 bits

Genome length = 10/11*Nr + 2/3 bits

Iris: the genomes

Page 47: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

"Fit" cooperatorsRandom cooperators

1. Fitness function

Population size

Fv : Number of variables

1

1

{60, 70}500 + 100*Nr

{0.02, 0.05, 0.1}{0.1, 0.2}

{1, 2}

Maximum generationsCrossover probabilityMutation probabilityElitism rate

measures the interpretability

encourages not−so−bad errorsFm : 1 − mse (mean square error)

the most important

2. Fuzzy CoCo parameters

Fc : Classification performance,

F = Fc * Fm

b(Fc + a*Fv) * Fm{ b

.

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne .

. .

Iris: Fuzzy CoCo set−up

Page 48: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

ICANNGA’01

8 97.3 % (2)

Iris results: classification (average rule)

Fuzzy CoCoNeurofuzzyConstructive Learning Methods

2 99.33% (2)

3 100 % (1.7)

4 98 % (2.6) 100 % (2.5)

5 100 % (3.3)

Wu (99)

RulesSimple GA

Shi et al (1999)FuGeNeSysRusso (1998)

Fuzzy CoCo

Hong (00) Hung (99) ICANNGA’01

2 98 % (1.5)

99.33% (2.3)3 96.2 % (4)

4 99.33% (2)97.4 % (4)

Rules

Con

trol

ler

Cla

ssifi

er

.

.

.

.Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

Page 49: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

PWPLSWSL

PWPLSWSL

ClassPL PW

Class

SW

Class

SL

Class

.

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology ..

.

Iris controller−type: A three−rule system

Page 50: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

setosa versic.

setosaPWPLSWSL

versic.setosa virgin.PWPLSL

virgin.

SL SW PL PW setosa versic. virgin.

virgin.

SW

versic.

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology

.

.

.

.

Iris classifier−type: A three−rule system

Page 51: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Fuzzy Subsystem

malignant

benign

DiagnosticInput Threshold SubsystemAppraisal

The

dat

abas

e

The

tes

t

..

..

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Breast cancer diagnosis: the WBCD problem

solu

tion

Pro

pose

d

Page 52: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

RulesMembership functions

P d

6 bits

V9.... ....ViV2

Genome length = 54 bits

3 bits

9 Variables * 6 bits

Ai = 0 or 3 (None)

Ai = 1 (Low)

d = [1;8]

3 bits

Ci = 1 (Benign)P = [1;8]

.

. .

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

V1

Ai = 2 (Malignant)Ai = 2 (High)

.

Genome length = 19*Nr + 1 bits

Nr rules * 19 bits

19 bits 1 bit

1 bit9 * 2 bits

CiA9A1 ....

CoRn...Ri...R1

The genomes

Page 53: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

"Fit" cooperatorsElitism rateMutation probabilityCrossover probabilityMaximum generations

Random cooperators

11000 + 100*Nr

[30−90]

{1,2,3,4}1

{0.1−0.6]

Fuzzy CoCo parameters

[0.02−0.3]

Population size

measures the interpretabilityFv : Number of variables

the most important performance measureFc : Classification performance,

F = Fc − a* Fv

Fitness function

. .

. .

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

Fuzzy CoCo set−up

Page 54: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

98.98% (5)

98.83% (5)

98.83% (5)

98.68% (3)

98.54% (4)

98.54% (5)

97.36% (4)

97.73% (3.9)

97.91% (4.4)

98.12% (4.2)

98.18% (4.6)

98.18% (4.3)

97.36% (4.0)

98.25% (4.7)

Evolved fuzzy rulesLearned Boolean rules

Fuzzy CoCo − IEEE TFS 2001AIM 1999

Fuzzy−geneticNeuroRuleSetiono (2000)

Rules

97.36% (4)1

97.36% (3)2

97.80% (6)98.10% (4)3

97.80% (−)4

97.51% (−)98.24% (5)5

98.10% (−)6

97.95% (−)7

Best

97.07% (4)

Average

WBCD results: classification (longest rule)

. .

. .

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

Carlos Andrés Peña−Reyes

Page 55: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Classification rate = 98.54%

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne .

if (v1 is Low) and (v3 is Low) and (v5 is Low) then (output is Benign)

v

if (v1 is Low) and (v4 is Low) and (v6 is Low) and (v8 is Low) and (v9 is Low) then (output is Benign)

else (output is Malignant)

1 3

v

.

v6 v8

v

v94 v5

.

Two−rules evolved system

.

Page 56: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Five-rule systems: 900.000 fitness evaluations

Five-rule systems: 480.000 fitness evaluations

Single-rule systems: 352.000 fitness evaluations

32.000 * (1000 + 100Nr) {worst case, Ncr=3}

Single-rule systems: 500.000 fitness evaluations

200 * (2000 + 500Nr)Number of fitness evaluations = Np * Gmax

Fuzzy GA: Single population (Peña & Sipper 99)

Computing requirements

Fuzzy CoCo: Cooperative coevolution (CEC-2000)

Number of fitness evaluations = 2 * Np * Gmax * (Ncf + Ncr)

Carlos Andrés Peña-Reyes

Logic Systems Laboratory - Swiss Federal Institute of Technology Lausanne. .

. .

Page 57: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

computer−assistedCOBRA system:

case interpretationreadingprotocol

mammogram

biopsy

recommendation329 benign (neg)187 malignant (pos)

516 readings{Database

Logic Systems Laboratory − Swiss Federal Institute of Technology

Carlos Andres Pena Reyes

. .

. .

The problem: mammography interpretation

Page 58: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

input

Fuzzy system

Proposal

Reading form

appraisal

Diagnostic decision unit

BiopsyReading

Database

Web−based user interface

Malignancy

Carlos Andres Pena Reyes

Threshold unit

Logic Systems Laboratory − Swiss Federal Institute of Technology. .

. .

COBRA system: internal view

Page 59: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

BinaryContinuousDiscrete

438

Variable type Number

.

. Logic Systems Laboratory − Swiss Federal Institute of Technology

Carlos Andres Pena Reyes

.

.

Understanding the database

Page 60: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

not encoded

Continuous variables (e.g., V1):3 var. x 2 par. x 7 bits = 42 bits

Discrete variables (e.g., V3):8 var. x 2 par. x 4 bits = 64 bits

Binary variables (e.g., V2):

Total genome length = 106 bits

Logic Systems Laboratory − Swiss Federal Institute of Technology

.

. .

NoneLow

.

High

Carlos Andres Pena Reyes

Benign Malignant

V V15V3

P1 P15 P’15P’1 P3 P’3

Ri: if (v1 is Ai1) and (v2 is Ai2) and (v3 is Ai3) and ... and (v15 is Ai15) then (output is Ci)

DB

V1 Vi ........ V15V2

.....

Pi P’i

1

Genome encoding for linguistic labels

Page 61: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

1 1

20

22

1

Clinical

120

11222222

if Sr = 0

if Sr = 1

+ Radiological

Total genome length = 20 x Nr +1

...Ri...R1

A3A2A1

RB

A15

Co

A11 A12

A9A8A7A4 A5 A6

Rn

Logic Systems Laboratory − Swiss Federal Institute of Technology

Ar2 ... Ar6 Sr CAc1 Ac2 Ac3 Ar1

Carlos Andres Pena Reyes

A10 A14

. .

. .

A13

Genome encoding for rules

Page 62: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

Specificity TN

Basic fitness (Fbase)

Accuracy reinforcement

(note: done only if Accuracy > 0.7)

Performance measures and fitness function

αSensitivity + Specificity1 + α

1 + βFbase + Accuracyβ

SensitivityTP

TP + FN

TN + FP

AccuracyTP + TN

TP+TN+FP+FN

TPTP + FN

PPV

..

Carlos Andrés Peña−Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology Lausanne

..

Page 63: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.9 0.91 0.920

5

10

15

20

25

2.502.22Vr

171712

Reff

0.9154

90.89780.8910Fitness

0.9109201510Nr

Best individual

2.4125

2.622.52Vr

15.7814.1512.039.17Reff

2.760.89340.87860.8754Fitness

25201510Nr

Average per class

2.59

2.70

0.8947

5

14

13

2

4

14

22

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology

.

..

.

Fuzzy CoCo results on 65 runs

Page 64: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

395/516211/329184/187

Ratio

186/289412/516226/329186/187

Figure

76.55%60.93%

98.40%

Figure

64.36%79.84%68.69%99.47%

Measure

PPV

64.13%SpecificitySensitivity

184/302

Ratio

Accuracy

9−rule17−rule

. .

. .

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology

Performance of two selected systems

Page 65: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

184/302395/516

Ratio

63.22%

Threshold = 2 Threshold = 3

SensitivitySpecificityAccuracyPPV

Measure

98.40%64.13%76.55%60.93%

Figure

184/187211/329

187/187208/329

76.55%60.71%

Figure

100.0%

395/516187/308

Ratio

Carlos Andres Pena Reyes

. .

.

Logic Systems Laboratory − Swiss Federal Institute of Technology

.

The 9−rule system with two different thresholds

Page 66: Fuzzy inference - cs.bgu.ac.ilsipper/courses/ecal051/lecon2.pdf · Gas Low OR Pressure Temp. & & & High Hot Cold Low OR High. Logic Systems Laboratory − Swiss Federal Institute

.

. .

Carlos Andres Pena Reyes

Logic Systems Laboratory − Swiss Federal Institute of Technology.

COBRA system: reading form