Monday evening, dusk sets.

At the end of October, there is already a slight sense of autumn wind in the air.

The people on the road are in a hurry, some people still have textbooks and documents in their hands, everyone is busy studying, and there are fewer people who fall in love.

Of course, it is also possible that these boys who study mathematics and physics can't find a girlfriend at all.

When he walked to the School of Mathematical Sciences, Su Mu's heart was a little apprehensive.

After all, he was a student of the School of Physics who came to the School of Mathematics to ask questions, and he always felt that something was not right, and the School of Physics and the School of Mathematics had been secretly competing for many years, wanting to compete for one up and down.

Not only that, Su Mu also saw a few familiar faces when he passed by, they were members of the previous Mathematics Olympiad national training team, because of his good memory, Su Mu had a certain impression of all the members of the training team.

I wanted to say hello or something, but he found that others didn't seem to know him, and he was slightly embarrassed when he staggered over.

The Faculty of Mathematical Sciences does not have a high floor.

The walls are white and the eaves are brown, giving it a solemn meaning.

According to the address given to him by Professor Chen Bing, Su Mu slowly walked towards an office on the second floor.

Professor Chen Bing's identity on the school website is the director of the teaching and research department of algebra and number theory in the School of Mathematical Sciences, and he occasionally goes to the docking of the Olympiad, the office is very easy to find, and when Su Mu passed, the door was half-hidden.

"Bang bang."

Su Mu didn't push the door directly, but knocked politely.

"Please come in."

A man's voice came from inside, but it wasn't Chen Bing.

Su Mu walked in, and then restored the door to a half-hidden state.

Now there are only three desks where Su Mu is, and there is a computer and some documents on each desk, Su Mu glanced around and found that Professor Chen Bing is not in the office now.

The male teacher who responded to him was about the same age as Professor Chen Bing, and he was talking to a male student at this time, when he was interrupted by Su Mu's arrival.

"What are you going to do?"

The male teacher opened his mouth and asked Su Mu, with a Beijing dialect in his tone.

Although Mandarin is spoken in many places in Beijing, if you are a local, you will still speak with a special childish pronunciation, and the pronunciation is relatively vague.

"I'm looking for Professor Chen Bing..."Su Mu replied weakly.

The teacher's tone was a little cold, although it was not malicious, but it didn't seem to have any more plans to communicate with Su Mu, just as he was a student who came to ask questions or find Chen Bing to have something.

"Professor Chen just went out temporarily, he should be back in a while, you can wait here for a while."

"Okay."

Su Mu nodded, and said no more, after he became a top student, most of the teachers he met were very enthusiastic, and it had been a long time since he had met such a cold teacher and professor.

Others didn't have time to take care of him, and Su Mu himself was happy to be idle, so he continued to look around at the environment of the office.

The whole room is not big, one wall is a large bookcase containing documents, the other wall is hung with some paintings and famous quotes, and a world map and calendar are pasted in the middle.

At least when Su Mu went to the high school office before, he didn't have this feeling at all, the office of Qianbei Middle School was like a company, the teachers went to work, and there were rows of desks in a classroom, and sometimes students came in to ask questions, and when they met their own subject teachers, they had to face the ridicule of several teachers at one time.

Ignoring Su Mu's scrutiny, the male teacher returned to the topic and communicated with his students.

The student has a study report in his hand, his name is Zhao Yuhui, and the instructor is the name of Xiang Jun written on it, and it should be the male teacher in front of him.

Su Mu noticed this, and his pupils contracted slightly.

In the school's official website, Xiang Jun is the teaching and research director of differential equations, and Su Mu's paper is mainly about differential dynamical systems and ordinary differential equations.

......

......

"Well, the idea of this little paper is still good, and there should be no problem in sending it to core journals, but there are still some places to concise about your layout." Xiang Jun opened his mouth to Zhao Yuhui and asked, "Do you want to use it as a graduation thesis?" ”

"Yes, yes."

"But I still suggest that you think a little more, for example, you can check the references on this differential equation that can be reduced, I know what you want to express, but you still don't express it in detail, and you have to add it in many places."

Xiang Jun turned out Zhao Yuhui's report, and seriously told him about some of the shortcomings in it, listening to the conversation between the two of them, Su Mu also knew something.

This Zhao Yuhui should be the senior brother of the senior in the Department of Mathematics, and when he graduated from Peking University, in addition to writing a graduation thesis, he also needed to submit a small paper that was published.

Now that he has been affirmed by his mentor, Zhao Yuhui's complexion is still very good.

"Zhao Yuhui, your grades are good, but I think if you want to go abroad, you still have to try SCI."

The analysis of the report came to an end, Xiang Jun sighed, and also talked about some family routines:

"Although I don't recommend studying abroad, if you really want to go out, the recognition of SCI is far more than that of your academic department in China."

Now the two more important journals in China are the core journals of Peking University and the C journals in the south, and a little further up is the international EI and SCI, SCI mainly focuses on theoretical research, EI is more engineering application, although the proportion of some domestic Chinese journals has gradually increased recently, but in the international recognition, there is still not as high as SCI and EI.

Zhao Yuhui nodded on the side, but his face was a little bitter, how could he not know this truth.

But in practice, it is very difficult.

Do you have any good suggestions? Actually, I mainly feel that the foundation and innovation are not good enough. ”

Just taking advantage of this opportunity, Zhao Yuhui also took advantage of the situation to continue to ask for help to Xiang Jun, since the mentor put forward this point of view, he must also have hopes for him, and the two began to talk about some details again.

......

......

"Huh? Su Mu, did you come so early? ”

"I thought you were coming after dinner."

Xiang Jun and Zhao Yuhui were communicating on the side, and Su Mu was also listening silently beside him.

I have to say that the level of knowledge of the tutors is really high, and when Xiang Jun explained to Zhao Yuhui the structure of the solution of the second-order linear differential equation of differential equations, Su Mu came up with a lot of new ideas.

However, before he could continue listening, Professor Chen Bing pushed open the door and entered.

Professor Chen Bing is wearing a black coat, which has not changed much from the previous mathematics international competition, but because he is in school, the whole person looks much more solemn.

When he spoke to Su Mu, he was kind and enthusiastic, and stretched out his hand to signal Su Mu to go to the innermost desk.

Su Mu also smiled slightly, and put the small paper he wrote on the table.

"Is that it? I'll take a look first. ”

Professor Chen Bing's face was very gratified:

"Actually, I was really surprised that you went to the physics department at that time, but in fact, it's okay, mathematics and physics are not separated, with your level of mathematics, no matter where you are in the future, you will have a good future."

"Multiple valid solutions for the initial values of ordinary differential equations and the general asymptotic forms of differential dynamical systems? You're really writing about the powertrain, which is a big problem. ”

He originally thought that Su Mu was just mentioning it on WeChat, and the specifics would definitely not be so complicated, but he didn't find that Su Mu really wrote about this.

"Differential equations and dynamical systems are specially set up by our institute for research teams, if you are really interested, I can..."

"Huh?"

Chen Bing was rummaging through Su Mu's things, but suddenly stopped halfway.

His eyes were slightly stunned.

Although Chen Bing's main research is algebra and number theory, he is also involved in differential equations and dynamical systems.

The full name of the mathematical dynamical system in English is (dynamicalsystem), which belongs to a concept in mathematics, there is a fixed rule in the dynamical system, which describes the change of a point in the geometric space with time, and there is a so-called concept of state in the dynamical system, which is a set of real numbers that can be determined.

However, Su Mu, a mere undergraduate, dared to combine differential equations and dynamical systems, and wrote a paper considering the initial value of the equation and a variety of effective solutions, which really surprised him.

"You wrote all of this yourself?"

Chen Bing asked a little uncertainly.

Although Su Mu's performance in the World Olympiad was very good, it was still completely beyond his expectations to be able to write this kind of thing.

Even if the content of the Olympiad is a little overclass, it will not be too overclass, and it is basically a derivative of the content of high school learning.

But this thing written by Su Mu, just by reading the previous page, is already completely something that undergraduates, and even graduate students need to consider!!

It has only been less than two months since the start of school, so the first thought that came to Chen Bing's mind was whether Su Mu had found a big deal on the Internet to joke with him.

However, Chen Bing and Su Mu have been in contact for a long time, and they don't think that he is this kind of person who likes to watch jokes casually, so Chen Bing is really puzzled.

"Well, I have been studying this matter for a long time, and the main reference is Professor Liao Shantao's exemplary equation system idea."

"And then there are some little ideas of my own, and I have learned quite a lot of things."

Su Mu nodded and explained.

"Then let me ask you, do you know what the central problem of differential dynamical systems is?"

Chen Bing tentatively investigated.

"It is a structurally stable system, for the simplest space [a,b], f∈Diff[a,b] not only means that f is homomorphic and differentiable, but also means that f^-1 is differentiable, and the absolute value of f' has a positive lower bound at [a,b], and if f is a differential homogeneus, then the g point near f of C1 is also a differential homomorphism." Su Mu replied calmly.

This is also the most basic point of his essay, and there is no pressure to answer it fluently.

Chen Bing's eyes lit up slightly.

Connoisseurs know if there is something as soon as they hear it.

For a high school student who has just entered college, it is already a terrifying thing to be able to straighten out this logic.

"Well, I'll take a look at it slowly, it's not this aspect that I'm mainly studying, you can wait a while."

Chen Bing took out a black-framed eye from the drawer, obviously became much more serious, and took out another pen. ”

"You have an electronic backup, don't you? I wrote directly on it. ”

"Yes, you can take your time, I'm not in a hurry." Su Mu nodded and slowly stepped aside.

After about three or four minutes of glancing, the more Chen Bing looked down, the more interesting he felt.

Because Su Mu's ideas on some points of view are really novel, in the construction of certain equations, he is so ingenious that he is a little applauded!

After all, I am a person who has studied mathematics for decades, and when I encounter such a point of view, I can't help but indulge in it!

"I finally understand why you won the special prize in the Olympiad...."

After reading two pages, Chen Bing sighed silently.

Su Mu not only has a novel idea, but also handles some details very well, and even if it weren't for the fact that there was no citation written later, his small paper could have been submitted directly, and it was the kind that must be submitted!!

"Wait a minute."

"I'll find another teacher to help you see some specific content about fractional equations."

This has been several times Chen Bing told Su Mu to "wait a little".

Su Mu smiled helplessly, he didn't wait and had nowhere to go now.

"Lao Xiang, do you have time now? Help come and have a look. ”

"Forget it, I'll go straight to you."

Chen Bing stood up and looked up at Xiang Jun, who was the director of teaching and research on major differential equations, and his understanding and specialization in this area must be deeper.

Although Chen Bing himself already has a lot of ideas and suggestions, it is better to let Xiang Jun take a look at the specific things.

"Huh? What's wrong? ”

Xiang Jun raised his head and stopped discussing with Zhao Yuhui.

What they discussed was actually to help Zhao Yuhui with some ideas, with a guiding nature.

It was almost discussed, and when he saw Chen Bing calling him, Xiang Jun stopped.

"This is one of my students' papers, you can help me read it, I think it's pretty good."

Chen Bing opened his mouth to explain.

"Okay." Xiang Jun nodded, glanced at Su Mu, and was a little surprised.

Chen Bing is now mainly in the second and third years of undergraduates, and he generally does not have to be responsible for the thesis, and he has worked with Chen Bing for many years, and rarely hears the word good from Chen Bing's mouth.

Xiang Jun, a top student in the School of Mathematics, knew everything in his heart, and he didn't waste time talking and communicating more because he didn't have any impression of Su Mu before.

"Differential dynamical systems? Junior? ”

Xiang Jun looked at the topic and glanced at Su Mu again.

The course in the junior year was all led by Xiang Jun and another teacher, but he really didn't have any impression of Su Mu.

He opened the first page and continued to read, and within two seconds, his expression was surprisingly consistent with Chen Bing.

As a teacher of this course for many years.

They discovered the advantages and innovative ideas of this little paper at the first time!!

"Yes."

Xiang Jun's body instantly sat up straighter.

Zhao Yuhui on the side was stunned.

When Xiang Jun was discussing the paper with him just now, he was in a very casual posture, but now, just after reading a few paragraphs, he obviously became stunned.

Zhao Yuhui's afterglow did not leave directly, but also looked at what Su Mu wrote curiously.

Differential Dynamical Systems is a major elective for undergraduate and graduate students in mathematics and applications, and can be skipped if they are not particularly interested.

Is it a graduate student's senior?

How to look young.

Zhao Yuhui is in his senior year this year, and he can learn differential dynamical systems, but he has not started to practice in his junior year this year, and his senior year is his classmates.

Su Mu is definitely not in the same class as him, so Zhao Yuhui subconsciously thinks that Su Mu is the senior of his graduate school.

......