Knowledge base

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Quick Questions

Shade in the A or B circle for each question.

1. What does the knowledge base of an expert system store?

A Facts and information about the subject

B The program that draws the screen layout

2. Where does the information in a knowledge base come from?

A Human experts in the subject

B Random guesses made by the computer

3. A medical expert system stores the symptoms and known causes of many illnesses. Which part holds this?

A Inference engine

B Knowledge base

4. Which statement is true about the knowledge base?

A It can never be changed once it is built

B It can be updated with new facts

5. Which part of an expert system holds the rules, such as IF-THEN statements?

A Rule base

B Knowledge base

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1knowledge base		AIF-THEN rules belong in the rule base. The knowledge base stores facts and information about the subject.
2knowledge base: add new fact		BUpdating the knowledge base so the expert system holds the latest facts about the subject
3The knowledge base holds facts about the subject that were gathered from human experts, such as a doctor		Cknowledge_base = facts from experts
4The knowledge base stores facts, but the rule base stores the IF-THEN rules used to reason		Dknowledge base = facts, rule base = rules
5knowledge base = IF-THEN rules		EThe part of an expert system that stores facts and information about a subject, gathered from human experts
6knowledge base = facts that can never change		FThe knowledge base can be updated with new facts, so it is not fixed.

Definitions

knowledge base

Fill in the Blanks

Complete each line of code by filling in the missing parts.

_____________ ← "facts from experts"

knowledgeBase.___("new virus fact")

________ ← "IF fever THEN rest"

knowledgeBase _ "Flu causes fever"

______ "new fact" TO knowledgeBase

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A knowledgeBase ← []

B fact ← "Fever is a symptom"

C APPEND(fact, knowledgeBase)

Question 2

A newFact ← "Flu has fever"

B IF newFact NOT IN KB THEN

C APPEND(RB, newFact)

D ENDIF

Question 3

A knowledgeBase ← rules

B ruleBase ← rules

C result ← USE(ruleBase, facts)

Question 4

A source ← "human expert"

B fact ← ASK(source)

C APPEND(knowledgeBase, fact)

D OUTPUT LENGTH(knowledgeBase

Question 5

A source ← "random website"

B fact ← GETFACT(source)

C APPEND(knowledgeBase, fact)

Answer Key

Knowledge base

Section A: Quick Questions

A — Facts and information about the subject

A — Human experts in the subject

B — Knowledge base

B — It can be updated with new facts

A — Rule base

Section B: Match the Pairs

knowledge base → The part of an expert system that stores facts and information about a subject, gathered from human experts

knowledge base: add new fact → Updating the knowledge base so the expert system holds the latest facts about the subject

The knowledge base holds facts about the subject that were gathered from human experts, such as a doctor → knowledge_base = facts from experts

The knowledge base stores facts, but the rule base stores the IF-THEN rules used to reason → knowledge base = facts, rule base = rules

knowledge base = IF-THEN rules → IF-THEN rules belong in the rule base. The knowledge base stores facts and information about the subject.

knowledge base = facts that can never change → The knowledge base can be updated with new facts, so it is not fixed.

Section C: Definitions

knowledge base — The part of an expert system that stores facts and information about a subject, gathered from human experts. It can be updated with new facts. The rule base holds the rules.

Section D: Fill in the Blanks

knowledgeBase ← "facts from experts"

knowledgeBase.add("new virus fact")

ruleBase ← "IF fever THEN rest"

knowledgeBase ← "Flu causes fever"

APPEND "new fact" TO knowledgeBase

Section E: Spot the Error

C — The arguments are the wrong way round. APPEND takes the list first, then the item to add, so the fact is stored in the knowledge base with APPEND(knowledgeBase, fact).

C — A new fact must be added to the knowledge base (KB), not the rule base (RB). The rule base holds rules, not facts. The line should be APPEND(KB, newFact).

A — The knowledge base stores facts about the subject, not rules. The rules belong in the rule base. The line should be knowledgeBase ← facts.

D — The closing bracket is missing. The line should be OUTPUT LENGTH(knowledgeBase) to output how many facts are stored.

A — The facts in a knowledge base are gathered from human experts, not from random websites. The line should be source ← "human expert".