It turns out that the fourth question from Guo Haitao is not an Olympiad problem in the strict sense, but more like a systematic and complex logical operation.

Compared with the Olympiad problems, this kind of operation close to practical value is obviously much higher in difficulty, and the data involved is also huge and complex, and ordinary people will feel nowhere to start in the face of this kind of thing.

"You don't have to figure out the final answer to this question, you just need to figure out a solution. Guo Haitao on the side reminded Duan Yun.

"Uh. Duan Yun replied without raising his head.

"It doesn't matter if you can't think of it today, you can take it home and think about it slowly, and tell me when you think about it. Guo Haitao said with a smile again.

Obviously, Guo Haitao didn't think that Duan Yun could solve this question in an afternoon.

In fact, Guo Haitao didn't expect Duan Yun to answer his fourth question at all, because it was not a question at all, but a paper published in an international mathematical journal by Guo Haitao a few years ago!

In the past ten years, few new theories have appeared in advanced mathematics, and even Guo Haitao, who has a very high attainment in mathematics, has not proved new mathematical theories.

The most brilliant part of his dissertation lies in his unique understanding of the limit theory of higher mathematics and its flexible application to practical feasibility, and from this point of view, Guo Haitao can indeed be called a master of mathematics.

In addition, it is almost impossible to complete the large number of computing manpower listed in this paper, and Guo Haitao also used computers and some programming technology to finally complete the verification of this paper, which is quite cumbersome and complicated, and it really took Guo Haitao a lot of time and energy.

After the publication of this paper, it also caused a wave of enthusiastic responses in the international mathematical community, which is also an affirmation of Guo Haitao's academic level!

And the reason why Guo Haitao took out such a test question for Duan Yun to answer this time was that he didn't expect him to answer it at all, but just hoped that he could understand that there are people outside the sky, and there are endless truths to learn.

In fact, Duan Yun did feel that this problem was almost BT difficult, even with his master-level math level, it was still impossible to solve it easily!

But this also unexpectedly aroused Duan Yun's 'fighting spirit'!

This time, Duan Yun and Guo Haitao asked for a whole pile of blank paper.

Duan Yun began to think for more than ten minutes.

This is something that Duan Yun has never seen before, you know, when he participated in the National Mathematics Olympiad in the past, with his master-level mathematical mastery, he almost had the answer in his mind instantly, and he spent time thinking about how to compress the steps to solve the problem.

But this time, just looking for a reasonable way to solve the problem, Duan Yun spent so long, it was indeed the first time since he became a master of mathematics!

"Knock knock!" At this time, there was a knock on the door outside the house, and Guo Haitao immediately stood up and went to open the door.

When the door opened, an old woman with silver hair and simple clothes appeared at the door, carrying a plastic bag containing vegetables.

Duan Yun only glanced up at this time, judging from the photo he saw in the photo frame placed in the bookcase just now, this woman should be Guo Haitao's wife.

"Hello master!" Seeing this, Duan Yun hurriedly got up and said hello respectfully.

"Hehe, you sit, you sit!" Guo Haitao's wife obviously often saw her husband taking students home, so she didn't have a big reaction, but after smiling at Duan Yun, she walked into the kitchen with Guo Haitao with vegetables.

In fact, Guo Haitao's wife was also a professor in Huaqing in her early years, and the two have been in love for many years, Guo Haitao even gave up the opportunity to study in a famous foreign university when she was young, and until now Huaqing University still passes the love story of Guo Haitao and his wife into a beautiful story.

However, this was not something that Duan Yun cared about, and at this time, he only had this question in his eyes.

As if he had a sudden inspiration, Duan Yun picked up the pen and paper and began to calculate quickly.

Compared with ordinary math masters, Duan Yun's mental arithmetic ability is quite powerful, even comparable to that of a computer! Therefore, when solving the difficult problem that requires a lot of calculations given by Guo Haitao, he has a calculation speed that is far stronger than that of ordinary people.

"Rustle!"

Duan Yun's pen tip quickly swiped across the paper, and in less than five minutes, the formula for the operation had already filled three sheets of paper!

The calculation of Duan Yun is still proceeding at a rapid pace.

At this time, Guo Haitao and his wife were cooking dinner in the kitchen, talking and laughing with each other, obviously having a very good relationship.

Minutes and seconds passed.

Duan Yun's calculations had filled twenty sheets of paper, and there was still no sign of stopping.

"Duan Yun, let's get ready to eat. At this time, Guo Haitao had already set up the folding table in the restaurant, turned his head and said to Duan Yun.

"Hmm. Duan Yun replied casually, but there was still no sign of stopping.

"I said, don't be in a hurry about this question, you can take it home and calculate it slowly, let's eat first. Guo Haitao walked up to Duan Yun and reminded him with a smile.

"Hmm. Duan Yun still responded, but still didn't look up.

"Actually, this question ...... Huh?" Guo Haitao was about to settle Duan Yun to eat again when his eyes came into contact with the dozens of calculation drafts that Duan Yun had in his hand, and he was stunned.

The next moment, he walked to Duan Yun's side and picked up the draft that Duan Yun had written, and after just flipping through it twice, his face showed a look of disbelief shock.

"This ...... This is all what you calculated just now?" Guo Haitao asked repeatedly.

"Hmm. ”

“……”

At this time, Guo Haitao was completely stunned.

He could naturally see that Duan Yun's idea of solving the problem was correct, and what shocked him even more was Duan Yun's extraordinary computing ability.

You must know that because Guo Haitao's thesis topic requires quite amazing calculation steps, so that in the process of solving the problem at the beginning, many important steps are finally completed by relying on computer programs, and if it is calculated manually, of course, it is also possible, but it takes a lot of time and energy, and even with Guo Haitao's mental arithmetic ability, it will take at least three or four months!

And now Duan Yun has only taken less than an hour, and he has already written hundreds of operation steps, which is close to one-fifth of the total amount of calculations!

"Genius, it's really a genius!"

Holding the calculation draft written by Duan Yun, Guo Haitao read it several times, and then slowly put it down.

In fact, he didn't expect Duan Yun to find the solution to this problem at all, after all, many of the solutions to this problem involve the most cutting-edge thinking and arguments in today's mathematical world.

But now Duan Yun has not only found a way to solve the problem, but also completed nearly one-fifth of the operation steps at an incredible speed, such a performance against the sky has far exceeded Guo Haitao's imagination!

Guo Haitao, who gradually came back to his senses, looked at Duan Yun who was engrossed beside him, and shouted loudly into the kitchen:

"Xiaoru, add another dish, cut the beef for me, I'm going to take charge of it myself today!"