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241-320 Design Architecture and Engineeringfor Intelligent System

Suntorn Witosurapot

Contact Address:Phone: 074 287369 or

Email: [email protected]

January 2010


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Lecture 13:

Expert System

(CLIPS Tutorial)


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241-320 Design Architecture &Engineering for Intelligent System Knowledge Representation andReasoning - part 3 (Rule-based) 3

Recall: CLIPS Expert System Shell

It is an XPS shell tool for building expert systems.

rule-based, forward-chaining system

multi-paradigm programming language (rule-based,

object-oriented and procedural like LISP)

We will use CLIPS to illustrate many of the conceptsand methods

Suggest to download the latest version of ApplicationInstaller on Windows Platform


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In this lecture, you should

be familiar with the important concepts and methodsused in rule-based XPS shells

facts, rules, pattern matching, agenda, working memory,

forward chaining understand the fundamental workings of an XPS shell

knowledge representation

reasoning

apply rule-based techniques to simple examples evaluate the suitability of rule-based systems for

specific tasks dealing with knowledge


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Recall: CLIPS Expert System Shell

a tool for building expert systems.

Its name stands for C Language Integrated Production System

CLIPS is a multi-paradigm programming languagethat provides support for rule-based, object-oriented,and procedural programming.

You can download it from:

http://clipsrules.sourceforge.net/index.html Download Installer version on Windows Platform


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CLIPS in PC

Double click from the shortcuts


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CLIPS Desktop Environment

You can clear the desktop area with a command fromthe menu bar.


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CLIPS Tutorial

We will take the tutorial given in the CLIPS mainpage to study in our class.


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CLIPS Tutorial 1: Facts and Rules

After the prompt CLIPS>, any valid commands canbe use, e.g. the commands in below table.


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Facts and rules: General view


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Facts and rules: General view of Facts


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Example: Insert / list / remove facts

1


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Example: Clear the system

We should now clear everything before moving tolearn about the next topic.

Recheck to seewhether or not it

is really clear.


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Facts and rules: General view of Facts


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Example: Rules

Rules: IF THEN

The IF part

The THEN part

The rule name

Q: Can you explain the rule above?


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Example: Rules (cont.)

Doing what??

Q: Explain why a new fact is

occurred after running theduck rule?

This is a new fact!

A: It is inferred by the rule.


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This is the power of rule-based programming - theability to make inferences from data, particularly as the results of

one rule can be used as the pattern for another.

Now add the rule

Clear all facts, but therules will be untouched

Q: Can you explain the rule above?


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Since we just clear all facts, it is easy to see that nofact exists. Then, we insert 2 new facts.

No fact is left!

Adding

2 rules


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Q: Guess how many factswill be in the system, afterrunning the rule?

A: See the picture below

Two new facts


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Rewrite the first rule, this time with the multiple actions

Whenever you run the rules, you'll get a message onscreen as well as the asserted quack fact.


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CLIPS Tutorial



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Tips: Loading scripts from file

You can download scripts from a file (rather thantyping them every time you use them).


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CLIPS Tutorial 2: Patterns and actions

We can specify facts using the deffacts structure,but if you add the word startup it will loaded it willrecreated every time a (reset) is executed.


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CLIPS Tutorial 2:Patterns & actions

(cont.)

Here is showing thatit has triggered four

times, once for eachfact matching the(animal ?) pattern.

The ? symbol is a

wildcard, which willmatch any symbol.

No fact atthis moment

But scripts is inaction after thisreset command


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CLIPS Tutorial 2: Matching things

From the facts and rule above,

this results is produced.Q: What animal are represented

are on each line?


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CLIPS Tutorial 2: Variables in patterns

We can use variablee.g. ?name in the rule

Rule: (animal dog) (animal cat) (animal duck) (animal turtle)


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CLIPS Tutorial 2: Getting data from the user

CLIPS gets information from the user by means ofthe (read) function.


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Tips: Naming the rules and facts

Please be noticed how rules or factsshould be named in this example.

This decision treerepresents a small

section of the diagnosisof a cars failure to start.

Each rounded box is arecommended remedy

Each rectangular box is pieceof evidence, which might berepresented by a fact such as(lights-working no) or(petrol yes).


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Tips: Save the script to file

If you want to save your working script for future use,you can use the save function which returns TRUEif there were no errors in the process of saving.


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CLIPS Tutorial



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CLIPS Tutorial 4: Templates & conditions

We have learned how facts can be created. In somecase, we may need to link them together.

(age Andrew 20)(weight Andrew 80)(height Andrew 188)(blood-pressure Andrew 130 80)(age brenda 23)

(weight brenda 50)(height brenda 140)(blood-pressure brenda 120 60)

Ex: an application

which is to try todetermine thegeneral fitness ofpeople

Q: What is thecommon amongeach set of facts?


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CLIPS Tutorial 4: Templates & conditions(cont.)

A kind of record datastructure can be used;here it is called template

(deftemplate personal-data(slot name)(slot age)(slot weight)(slot height)

(multislot blood-pressure) )

(assert (personal-data (name Andrew) (age 20)(weight 80) (height 188) (blood-pressure 130 80)))

You don't have to specify all the information;

(assert (personal-data (weight 150) (age 23) (name Brenda)))


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Or use in a deffactsstructure;

(deftemplate personal-data(slot name)(slot age)(slot weight)(slot height)

(multislot blood-pressure) )

(deffacts people(personal-data (name Andrew) (age 20) (weight 80)

(height 188) (blood-pressure 130 80))

(personal-data (name Cyril) (age 63) (weight 70)(height 1678) (blood-pressure 180 90)))


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Any slot can be referred by name

The function modify is used tochange the value of one or moreslots on a fact.

(deftemplate personal-data(slot name)(slot age)(slot weight)(slot height)(multislot blood-pressure) )

(defrule birthday?birthday


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Template-based facts can be used in rules just asordinary facts.

(defrule birthday?birthday


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CLIPS Tutorial

You may proceed to the other tutorials on your own!


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Last note & Exercise

You are now roughly understand how to programCLIPS for building the expert system.

For better understanding, you are encouraged to learn

more tutorials that will be uploaded to LMS server later.

Although CLIPS can do more than what we learned,that are all enough for our learning in this course.

Since it would be useless if we havent done anythingon CLIPS, let exercise on a homework, which detailsare in next slide.


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241 320 Design Architecture &S Kno ledge Representation and 38

Exercise:

You are about todevelop an expertsystem that canhave the diagnosisof a cars failure

The decision treegiven here can beused as a guideline

Interaction with useris preferred

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