Rule base

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. Which of these is a rule that could be stored in the rule base of an expert system?

A The patient feels hot and tired

B IF temperature > 38 THEN fever

2. What does the rule base of an expert system contain?

A IF-THEN rules that link facts to conclusions

B The screen the user types questions into

3. In the rule IF rain = true THEN take umbrella, which part is the conclusion?

A take umbrella

B rain = true

4. Which rule needs BOTH facts to be true before the conclusion is drawn?

A IF fever AND rash THEN measles

B IF fever OR rash THEN measles

5. The rule is IF fever OR cough THEN see doctor. A patient has a cough but no fever. What is the result?

A No conclusion is drawn

B The conclusion is see doctor

Match the Pairs

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

Left column		Right column
1IF fever = yes THEN suspect = flu		AIF engine = silent THEN fault = battery
2IF rain = yes AND wind = high THEN storm = likely		BThe parts are in the wrong order: a rule must start with IF condition and then give THEN conclusion
3A rule links a fact to a conclusion using IF and THEN		CA single rule in the rule base: if the condition is true, the system draws the conclusion
4OR lets a rule fire when at least one of its conditions is true		DIF cough = yes OR sneeze = yes THEN check = cold
5THEN suspect = flu IF fever = yes		EAND makes the rule impossible to meet, because a temperature cannot be above 30 and below 10 at once
6IF temp > 30 AND temp < 10 THEN weather = hot		FA rule where both conditions must be true before the conclusion is drawn

Definitions

rule base

Fill in the Blanks

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

__ fever = TRUE THEN diagnosis = "flu"

IF fever = TRUE ____ diagnosis = "flu"

IF fever = TRUE ___ cough = TRUE THEN diagnosis = "flu"

IF rash = TRUE __ itch = TRUE THEN advice = "see doctor"

IF light = "red" THEN action = "stop" IF _____ = "green" THEN action = "go"

Spot the Error

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

Question 1

A IF fever AND cough flu

B IF rash THEN measles

C IF sneeze THEN cold

Question 2

A IF no_fuel THEN no_start

B IF flat_battery THEN no_start

C IF smoke OR overheat ELSE stop

Question 3

A IF Mon THEN weekday

B IF Tue THEN weekday

C IF Sat AND Sun THEN weekend

Question 4

A IF overdue THEN fine

B THEN block_card IF fine

C IF paid THEN unblock_card

Question 5

A light = red THEN stop

B IF light = green THEN go

C IF light = amber THEN slow

Answer Key

Rule base

Section A: Quick Questions

B — IF temperature > 38 THEN fever

A — IF-THEN rules that link facts to conclusions

A — take umbrella

A — IF fever AND rash THEN measles

B — The conclusion is see doctor

Section B: Match the Pairs

IF fever = yes THEN suspect = flu → A single rule in the rule base: if the condition is true, the system draws the conclusion

IF rain = yes AND wind = high THEN storm = likely → A rule where both conditions must be true before the conclusion is drawn

A rule links a fact to a conclusion using IF and THEN → IF engine = silent THEN fault = battery

OR lets a rule fire when at least one of its conditions is true → IF cough = yes OR sneeze = yes THEN check = cold

THEN suspect = flu IF fever = yes → The parts are in the wrong order: a rule must start with IF condition and then give THEN conclusion

IF temp > 30 AND temp < 10 THEN weather = hot → AND makes the rule impossible to meet, because a temperature cannot be above 30 and below 10 at once

Section C: Definitions

rule base — The part of an expert system holding IF-THEN rules (IF condition THEN conclusion) that link facts to conclusions, often joined with AND/OR, which the inference engine uses to reach answers.

Section D: Fill in the Blanks

IF fever = TRUE THEN diagnosis = "flu"

IF fever = TRUE AND cough = TRUE
THEN diagnosis = "flu"

IF rash = TRUE OR itch = TRUE
THEN advice = "see doctor"

IF light = "red" THEN action = "stop"
IF light = "green" THEN action = "go"

Section E: Spot the Error

A — The rule is missing the THEN keyword. A rule must be written IF condition THEN conclusion, so it should be IF fever AND cough THEN flu.

C — ELSE is used instead of THEN. In a rule base the conclusion follows THEN, so the line should be IF smoke OR overheat THEN stop.

C — A day cannot be both Saturday and Sunday, so an AND rule would never fire. OR is needed because either fact is enough: IF Sat OR Sun THEN weekend.

B — The parts of the rule are the wrong way round. The condition comes after IF and the conclusion after THEN, so it should be IF fine THEN block_card.

A — The rule does not start with IF. Every rule must begin with IF followed by the condition, so it should be IF light = red THEN stop.