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Question 1In a fictional society, politicians never tell the truth, and non-politicians always tell the truth.
When a foreigner sees three locals, he asks the first of them, "Are you a politician?"The man replied.
The second person relayed the first person's answer that he denied being a politician.
The third person said that the first person was indeed a politician.
How many politicians are there among these three locals?
Answer: The first person can only answer "yes" or "no".
If the answer is "yes", there will be a contradiction.
Because if he is a politician, but a politician will only tell lies, he cannot say "yes".
If he is a non-politician, but a non-politician will only tell the truth, so he can't say "yes" either.
So, the first person can only answer "no".
But at this time, it is not possible to confirm whether the first person is a politician or not.
The second person is telling the truth (i.e. the first person is not a politician) and he is a non-politician.
If the third person is telling the truth, then the third person is a non-politician, and the first person is a politician.
If the third person is telling a lie, then the first person is not a politician, and the third person is a politician.
So, only one of the three is a politician.
Question 2On one train, the crew consisted of brakemen, stokers, and engineers, whose names were Jones, Robinson, and Smith (in no particular order).
There were also three passengers on this train with the same names as the crew, Mr. Jones, Mr. Robinson, and Mr. Smith.
The following facts are known:
a.Mr. Robinson lives in Detroit.
b.The turnstile lives between Detroit and Chicago.
c.Mr. Jones' salary is $40,000 a year.
d.Smith once defeated the stoker in a billiards match.
e.One of the three passengers is a neighbor of the driver, who earns exactly three times as much as the driver's salary.
f.Passengers who live in Chicago have the same name as the turnstaker.
What is the name of the engineer?
Answer. 1, according to D, knew that Smith was not a stoker.
2. Based on A, B, C, and E, it was determined that Mr. Smith was the neighbor of the gatekeeper.
3. According to the first 2 steps, knowing that Mr. Robinson lives in Detroit and Mr. Smith lives between Detroit and Chicago, it is determined that Mr. Jones lives in Chicago.
4. According to the conclusion of F and the third step, it is determined that the gatekeeper is Jones.
5. Based on the first and fourth steps, determine that Smith is an engineer.
Self-study logic, welcome to communicate**.
I'm Zheng Yi, and I'll continue to make progress with you.
Portions of the text are quoted from Owen in Introduction to Logic (15th ed.). m.Ke Pi (author), Chinese Renmin University Press, November 2022.