Transcript Document 7676231

Life Cycle
Life Cycle of a Classical Software
Development
Requirement
Analysis
Design
Implement
Test /
Maintenance
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Problems
Traditional Life Cycle model is Linear
 Every Step can be completed before the
next starts
Requires exact understanding of the problem
at the start of the project
Ability to trace back to the original
requirements
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Expert System Life Cycle
Basic Principle:
Iteration are inevitable
 Why?
No body understands the problem exactly
The problem becomes severe when the
system under consideration is Knowledge
based
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
ES Development Life Cycle
Problem
Selection
Prototype
Construction
Implement
Evaluation
Lahore University of Management Sciences,
Lahore, Pakistan
Formalisation
Long-Term
Evolution
Dr. M.M. Awais- Computer
Science Department
Unique Characteristics
Customer is involved through out the
process
Frequent Demonstrations are encouraged
Change is viewed as healthy
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Details: Problem Selection
Problem Survey
Candidate Selection
Candidate Analysis
Domain Applicability
Expert Availability
Problem Scope
Cost/benefit Analysis
Final Candidate Selection
Task Characteristics (defining the nature of the ES)
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Details: Problem Selection
Candidate Selection
Does the task require expert knowledge?
How much benefit the system will be to
the organisation.?
Is the solution valuable for long time to
the organisation.?
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Problem Selection: Example
Black Board Architecture
Used for problems when knowledge acquisition
is done from different sources
Rule and Control Scheme
Used under conditions when exact rules can be
defined for a problem. The scope of application is
also limited
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Problem Selection: Example
An expert System has to be developed for
incorporating knowledge from a manufacturing
plant. The knowledge from various shops have
to be collected into a control unit, that would
indicate the time delays of the complete
assembly plant. The system should also
indicate the remedies for reducing the time
delays in the each shop of the plant such as
paint shop, heat treatment shop etc. The system
to be equipped with on-line modification
facility for each shop.
TASK CHARACTERISTRICS !!!!!!!
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Problem Selection: Solution
Black Board
Rule and Control
Diverse Source
of knowledge
from each shop
For each Shop
Cooperating
Knowledge
sources
Lahore University of Management Sciences,
Lahore, Pakistan
With
Modification
Facilities such as
knowledge base
editor
Dr. M.M. Awais- Computer
Science Department
Prototype Construction
What should be the primary aim of
Prototyping?
To learn more about the domain
To gain deeper understanding of the nature
of the project
To demonstrate overall systems’
functionalities
To test the initial design
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Prototype Construction
Should the prototype be kept for detailed
design?
Keep only those parts of the prototype whose
level of implementation quality is similar to
that expected of the final system
If it has to be discarded that should only be
done after guidelines are for new
implementation are extracted from the
experience
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Formalisation
Formalisation is the development proces
Record key understandings from the prototyping phase
Plan the implementation
Provide visibility at each level
Draw implementation plans
Revisit pre formalisation steps to improve
When formalisation is inevitable?.
For large scale systems the formalisation step becomes
very important
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Formalisation: Steps
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Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Implementation Plans
Prototype revisited
System framework development
Core knowledge Acquisition
Coding
Internal Integration
Internal verification
Revision of inference engine
and representation methods
Establishing and revising
knowledge base partitioning
Further verification
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Core Knowledge Development
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Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Evaluation
Adequacy
Adequacy
Gradual degradation Vs Sudden Collapse
Task difficulty
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Lahore, Pakistan
Task difficulty
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Science Department
Complete Example
Want to develop an expert system for detecting
fire and suggesting remedial action
Gather Initial Data
Fire occurs when the room temperature is high and
smoke appears
Temperature can be measured using Temperature gauge
Smoke can be indicated using smoke detector
Remedial action could be to assert that fire is on and then
to call the fire brigade/or switch on the sprinklers
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Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Complete Example
Carry Out Task Characteristics
What should be the architecture of the knowledge
representation?.
Black Board or Rule control based
Rule Based Control
Represent knowledge in appropriate manner
Tree format
Extract rules from the tree
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Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Tree Format
Switch on
the sprinklers
Fire
Alarm beeps
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smoky
hot
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Rules
IF alarm beeps THEN smoky
IF hot AND smoky THEN fire
IF fire THEN switch on the sprinklers
Which rule should be fired?.
Depends on the state of the initial database of facts
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Rules Based System
Need to assert the initial facts in a
database and then to change them
after each rule is fired
Control Scheme
Rules
IF alarm beeps THEN ADD smoky
IF hot AND smoky THEN ADD fire
IF fire THEN ADD switch on the sprinklers
Lahore University of Management Sciences,
Lahore, Pakistan
Database of facts
alarm beeps
hot
Dr. M.M. Awais- Computer
Science Department
Rules – Representation Using CLIPS
IF temperature(R,hot) AND
environment(R,smoky) THEN fire-in(R)
(defrule fire-alarm
(temperature ?r1 hot)
(environment ?r1 smoky)
(assert (fire-in ?r1)))
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Problem
A problem faced by an organisation is to select candidates
from among a very large pool of individuals for appointment
to advanced training. Since the cost incurred for such training
is considerable it is deemed important to carry out this process
in a logical, efficient manner. The selection is done in two
phases. First a test is conducted followed by the second phase
of physical examination and evaluation. People who perform
good go straight to the second phase. After the 2nd phase the
Outstanding candidates are approved while poor are reject and
average are placed on the waiting list. The marginal candidates
after the first phase are examined on the bases of their job
performance. Good performers in this test are allowed for the
second phase and rest are rejected.
Lahore University of Management Sciences,
Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department
Decision Tree
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Lahore, Pakistan
Dr. M.M. Awais- Computer
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Rule Extraction
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Lahore, Pakistan
Dr. M.M. Awais- Computer
Science Department