How an expert system reaches a conclusion

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Quick Questions

Shade in the A or B circle for each question.

1. Which component of an expert system first takes the user's answers to its questions?

A The inference engine

B The expert system interface

2. Which component applies the rules to the user's answers and the knowledge base?

A The inference engine

B The rule base

3. Which is the correct order of operation?

A Interface, inference engine, interface

B Inference engine, interface, knowledge base

4. Which component displays the final conclusion to the user?

A The knowledge base

B The expert system interface

5. True or false: the inference engine uses both the user's answers and the knowledge base to reach a conclusion.

A True

B False

Match the Pairs

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

Left column		Right column
1interface -> inference engine -> interface		AThe sequence starts at the wrong place. The user's answers must be taken in at the interface before the inference engine can reason.
2inference engine -> knowledge base		Binterface -> result shown to user
3The first step: the user's answers are taken in by the interface		CThe order an expert system works: the user answers at the interface, the inference engine reasons, then the interface shows the result.
4The last step: the interface shows the conclusion to the user		Duser answers -> interface
5interface -> knowledge base -> inference engine		EThe interface does not send the answers straight to the knowledge base. The inference engine must apply the rules to the answers and use the knowledge base.
6inference engine -> interface -> interface		FThe inference engine looks up facts and rules in the knowledge base to work out a conclusion from the user's answers.

Definitions

interface -> inference engine -> interface

Fill in the Blanks

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

1. The user types answers at the _________

2. The ________________ applies the rules

3. The interface shows the ______

interface -> ________________ -> interface

The inference engine uses the rules and the ______________ to reach a conclusion

Spot the Error

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

Question 1

A answers = interface.ask()

B rules = knowledge_base.get()

C result = engine.run(result)

D interface.show(result)

Question 2

A answers = engine.ask()

B result = engine.run(answers)

C interface.show(result)

Question 3

A Step 1: User answers questions

B Step 2: Interface applies rules

C Step 3: Interface shows result

Question 4

A INPUT answers

B result = INFER(rules)

C OUTPUT result

Question 5

A INPUT answers FROM engine

B result ← INFER(answers, rules)

C OUTPUT result TO interface

Answer Key

How an expert system reaches a conclusion

Section A: Quick Questions

B — The expert system interface

A — The inference engine

A — Interface, inference engine, interface

B — The expert system interface

A — True

Section B: Match the Pairs

interface -> inference engine -> interface → The order an expert system works: the user answers at the interface, the inference engine reasons, then the interface shows the result.

inference engine -> knowledge base → The inference engine looks up facts and rules in the knowledge base to work out a conclusion from the user's answers.

The first step: the user's answers are taken in by the interface → user answers -> interface

The last step: the interface shows the conclusion to the user → interface -> result shown to user

interface -> knowledge base -> inference engine → The interface does not send the answers straight to the knowledge base. The inference engine must apply the rules to the answers and use the knowledge base.

inference engine -> interface -> interface → The sequence starts at the wrong place. The user's answers must be taken in at the interface before the inference engine can reason.

Section C: Definitions

interface -> inference engine -> interface — The user answers questions at the interface; the inference engine applies the rules to the answers and knowledge base; the interface then shows the result.

Section D: Fill in the Blanks

1. The user types answers at the interface

2. The inference engine applies the rules

3. The interface shows the result

interface -> inference engine -> interface

The inference engine uses the rules and
the knowledge base to reach a conclusion

Section E: Spot the Error

C — The engine needs the user's answers to work out a conclusion. 'result' does not exist yet, so the line should be result = engine.run(answers).

A — The expert system interface asks the user the questions and takes their answers. The inference engine does not talk to the user. It should be answers = interface.ask().

B — Applying the rules is the job of the inference engine, not the interface. The interface only takes the answers and shows the result. Step 2 should say the engine applies the rules.

B — The inference engine must apply the rules to the user's answers, so the answers must be passed in too. It should be result = INFER(answers, rules).

A — The user's answers come in through the interface, not from the inference engine. It should be INPUT answers FROM interface.