a introduction to common kads

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A introduction to CommonKADS: structured knowledge engineering Guus Schreiber www.commonkads.uva.nl

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Page 1: A Introduction To Common Kads

A introduction to CommonKADS: structured knowledge engineering

Guus Schreiber

www.commonkads.uva.nl

Page 2: A Introduction To Common Kads

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Activities in knowledge-system development

Business context

modelling

Communicationmodelling

Knowledgemodelling

System design

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Why context modeling?

Often difficult to identify profitable use of (knowledge) technology

Laboratory is different from the ''real'' world Acceptability to users very important Fielding into ongoing process not self evident Often not clear what additional measures to

take

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How to analyze a knowledge-intensive organization?

How to analyze a knowledge-intensive organization?

describe organization aspects:• opportunity/problems portfolio• business context, goals, strategy• internal organization:

– structure– processes– people (staff: functional roles)– power and culture – resources (knowledge, support systems, equipment,…)

do this for both current and future organization• comparison, and first decisions on where to go

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Worksheets Organization Model

Organization Model

Problems &

Opportunities

GeneralContext

(Mission,Strategy,

Environment,CSF's,...)

PotentialSolutions

OM-1 OM-2

OrganizationFocus AreaDescription:

Structure

Process

People

Culture & Power

Resources

Knowledge

OM-3 OM-4

ProcessBreakdown

KnowledgeAssets

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Process “Housing”

primaryprocess

secondaryprocess

data entryof applications

magazineproduction

applicationassessment

residenceassignment

statisticalanalysis

policyinformation

:residenceassignments

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Example OM-3 for “Housing”

Task Performed by

Where Knowledge asset(s)

KI? Signifi-

cance

1. Magazine production

Magazine editor

Public service

- No 3

2. Data entry applications

Data typist / automated telephone

Residence assignment

- No 2

3. Application assessment

Assigner Residence assignment

Assessment criteria

Yes 5

4. Residence assignment

Assigner Residence

Assignment

Assignment &

urgency rules

Yes 5

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Knowledge modelling

Specific type of conceptual modelling• Only gradual differences with “general” conceptual

modelling

Knowledge modelling from scratch is time-consuming and difficult • Knowledge reuse is important theme

Patterns exist for types of problem-solving tasks• Base on typology of problem-solving tasks

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Analytic versus synthetic tasks

analytic tasks• system pre-exists

– it is typically not completely "known"

• input: some data about the system,• output: some characterization of the system

synthetic tasks• system does not yet exist• input: requirements about system to be

constructed• output: constructed system description

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Task hierarchy

knowledge-intensive

task

analytictask

classification

synthetictask

assessment

diagnosis

configurationdesign

planning

scheduling

assignment

modelling

prediction

monitoring

design

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Knowledge categories

Task knowledge• goal-oriented• functional decomposition

Domain knowledge • relevant domain knowledge and information• static

Inference knowledge• basic reasoning steps that can be made in the

domain knowledge and are applied by tasks

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Knowledge model overview

Disease(type)

Symptom(type)

Test(type)

hypothesize(inference)

verify(inference)

DIAGNOSIS(task)

Task knowledgetask goalstask decompositiontask control

Inference knowledgebasic inferencesroles

Domain knowledgedomain typesdomain rulesdomain facts

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Domain knowledge

domain schema• schematic description of knowledge and

information types• comparable to data model• defined through domain constructs

knowledge base• set of knowledge instances• comparable to database content• but; static nature

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Constructs for domain schema

Concept• cf. object class (without operations)

Relation• cf. association

Attribute• primitive value

Rule type• introduces expressions => no SE equivalent

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Example rule type

loanconstraint

restricts

person.income <= 10,000 RESTRICTS loan.amount <= 2,000

person.income > 10,000 AND person.income <= 20,000 RESTRICTS loan.amount <= 3,000

person

name: stringincome: integer

loan

amount: integerinterest-rate: number

1+

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Inference

fully described through a declarative specification of properties of its I/O

internal process of the inference is a black box• not of interest for knowledge modeling.

I/O described using “role names”• functional names, not part of the domain

knowledge schema / data model

guideline to stop decomposition: explanation

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Example inference: cover

complaint hypothesiscover

causalmodel

my car does not startfuel tank is empty

fuel tank is empty leads to lack of gas in engineif there is no gas in the engine, then the car does not start

dynamic input role dynamic output role

static role

inference

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Inference structure

complaint

cover

predict compare

obtain

expectedfinding

actualfinding

result

causal model

manifestation model

hypothesis

engine doesnot start

state dependencyrules

empty fuel tank gas dial = zero/low

gas dial = normal

not equalmanifestation

rules

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Task knowledge

describes goals• assess a mortgage application in order to

minimize the risk of losing money• find the cause of a malfunction of a photocopier in

order to restore service. • design an elevator for a new building.

describes strategies (methods, PSMs) that can be employed for realizing goals.

typically described in a hierarchical fashion:

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UML activity diagram for method control

cover

predict

obtain compare

[no more solutionsof cover]

[new solutionof cover]

[result = equal]

[result = not equal]

solution found

no solution found

startdiagnosisthrough

generate-and-test

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Assessment

find decision category for a case based on domain-specific norms.

typical domains: financial applications (loan application), community service

terminology: case, decision, norms

some similarities with monitoring• differences:

– timing: assessment is more static

– different output: decision versus discrepancy

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Example assessment task:mortgage assessment

Post condition: the application is assessed according to business rulesof the bank and the client is notified whether it is eligible

Mortgage Application

Eligible(): Boolean

ClientBank

*

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Mortgage domain information

Client

<customer attributes>

Mortgage

<mortgage attributes>

Mortgage Application

Eligible: Boolean

<mortgage application attributes>

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Assessment: abstract & match method

Abstract the case data Specify the norms applicable to the case

• e.g. “rent-fits-income”, “correct-household-size”

Select a single norm Compute a truth value for the norm with

respect to the case See whether this leads to a decision Repeat norm selection and evaluation until a

decision is reached

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Mortgage domain knowledge

Abstraction rules

IF customer.age =< 27THEN customeer.age-categroy := young

<other asbtraction rules>

norm rules

IF customer.age-category = youngTHEN risky :- true

IF mortgage.amount > 300.000THEN large-amount = true

<other norm rules>

decision rules

IF risky = true AND large-amount = trueTHEN application.eligible = false

<other decision rules>

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Template (pattern) for assessment task

case

abstractedcase norms

normvaluedecision

abstract

select

match

specify

evaluate norm

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Assessment control

abstract

match

select

specify

evaluate

[decision known] [decision unknown]

[no norm selected][norm selected]

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Claim handling for unemployment benefits

:claim

collectdata

dataentry

decide about claim

computebenefit

sendnotification prepare

payment

[no right][right]

claim handling finacialdepartment

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Normen en beslisregels voor WW beoordeling

Normen: Verzekerd Werkloos Wekeneis Jareneis

Beslisregels ALS niet verzekerd of

niet werkloos of niet voldoet aan wekeneis DAN geen WW

ALS wel wekeneis en niet jareneis DAN korte basisuitkering

ALS wel jareneis DAN loongerelateerde uitkering

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In applications: typical task combinations

monitoring + diagnosis• Production process

monitoring + assessment• Nursing task

diagnosis + planning• Troubleshooting devices

classification + planning• Military applications

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Example: apple-pest management

monitorpest

identifypest

plan preventivetreatment

plan curativetreatement

executetreatment

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Summary

Knowledge engineering is a specialized form of software engineering

CommonKADS: model-based approach to knowledge engineering

Reuse of task-specific knowledge models is important theme

Knowledge model often outlives application