Look simple, the example is as follows:
When the difference between X and Y is greater than one of them (let A be smaller than B and X be smaller than Y), it is necessary to determine:
a=7 b= 10 a=3 b=5
X= 17 Y=25 X=8 Y= 12
For A, the difference between X and Y is greater than A, then according to the hypothesis, the difference between the doomed value and the large value is greater than X. Since both are positive numbers, A can directly exclude the small value, so this situation is impossible.
Then, the difference between x and y is equal to or less than any number.
a=7 b= 10
X= 17 Y=23, with a difference of 6 x-ay-b.
a = 7 10 16
a = 13 4 10
a = 1 16 22
b = 10 7 13
b = 16 1 7
b = 4 13 19
The real answer is:
When A said he didn't know when he entered the topic as a party, it was obvious that he had considered 10 and 16 before. He would think, if b is 16, then b would exclude 1.
Because if it is a= 1, A will say that it knows, and 22 is obviously greater than 17. If you know the next sentence of b, then b is 16, because excluding a= 1 leaves a=7. If the result b is unknown, then b= 16 can be excluded.
At the same time, b will not be 4, otherwise b can get the result. The difference between 4 and 23 is 19, which is greater than 17, so b≠4. After that, 10 remains. From A's point of view, the result comes out, so A can get the result.
What matters is how b knows. Obviously, after B doesn't know, there are two considerations, a=7 or 13. For A, when a= 13, B has two possibilities, b=4 or b= 10. When a=7, b remains b= 10. Just now, B said he didn't know, and the excluded 16 was probably a=7. So if A is still uncertain, excluding a=7, the next sentence B can determine a= 13, and only a= 13 faces two possibilities: b=4 or b= 10. Now that A is determined, it is obvious that a=7, A can determine b= 10, and B will know a=7.
Numbers can be changed at will, and so on. Such a topic is usually three sentences, because for everyone, the other party has only three possible numbers, so the first person can say two sentences at most and the result will come out.