The train driver in the courtyard

At three o'clock in the morning, a transport plane landed at the Factory 221 airport.

On the runway, Li Aiguo hugged Chichi and shook hands with the comrades who came to see him off for the last time.

"Aiguo, have a safe trip!" Director Li shook hands with Li Aiguo.

Li Aiguo extended his hand to Professor Qin and said, "Old Qin, you can just work on the subsequent proof of the geometrization conjecture in your spare time. Don't waste too much energy."

Professor Qin originally planned to continue studying the Poincare conjecture.

Hearing this, he knew that Li Aiguo was worried that he would delay his work, so he nodded and said, "Aiguo, don't worry."

Li Aiguo also meant well.

Although we have theories like Li Aiguo, we are still a long way from completely solving the Poincare conjecture.

Many mathematicians have spent their entire lives trying to figure out this final step, but have still not been able to do so.

Li Aiguo waved at the old cat again, turned around and prepared to board the plane.

At this time, a GAZ jeep came speeding from the distance.

The jeep stopped and Chief of Staff Zhang of the Security Regiment got out of the jeep accompanied by a security officer.

Chief of Staff Zhang also saw Li Aiguo and looked a little unhappy.

He walked sideways past Li Aiguo and others, boarded the plane first, followed closely by the security officer.

Li Aiguo looked at Director Li and asked, "Director Li, what's going on?"

"Chief of Staff Zhang is in poor health and is not suited to the work of Factory 221. The old commander originally planned to have him return to the local area." Director Li squinted at Chief of Staff Zhang's back. "However, considering that Chief of Staff Zhang has participated in too many of Factory 221's work, he is already considered a confidential person. So after repeated considerations, the higher-ups transferred Chief of Staff Zhang to the Production and Construction Corps for a few years. Once he is declassified, he will be assigned another job."

These days, most frontier production corps are built in desolate areas with no human habitation for hundreds of miles around. It is a good place to house confidential personnel.

It's just that the conditions are too harsh.

Waving goodbye to comrades, the transport plane flew into the sky.

Along the way, Chief of Staff Zhang sat in a chair with his head drooping and said nothing. The security officer followed closely beside him with a vigilant look.

Li Aiguo had no intention of saying hello, and the atmosphere in the cabin was depressing.

More than two hours later, the transport plane made a temporary landing at the airport of the Frontier Production Corps. Chief of Staff Zhang stood up and walked downstairs accompanied by a confidentiality officer.

When he came to Li Aiguo's side, he stopped and seemed to want to explain something, but was reminded by the confidentiality officer: "Comrade Zhang, please pay attention to discipline."

Chief of Staff Zhang sighed, turned around and got off the plane. Li Aiguo could vaguely hear a voice coming from outside the cabin: "Welcome to Yanqi, I am from the Confidentiality Section of the 9th Agricultural Construction Division."

The plane took off again. Li Aiguo drew his collar closer, held Chichi in his arms, leaned against the wall of the cabin, and fell into a deep sleep.

****
On the twenty-eighth day of the lunar year, Li Aiguo returned to the capital city which belonged to him (did not belong to him).

The Chinese New Year is coming soon.

The faces of the people walking on the street were filled with joy, the children were playing freely, and the air was filled with a happy atmosphere.

Li Aiguo got off the jeep, waved goodbye to Old Zhang from the weather station, and walked into the courtyard carrying large and small bags.

The third uncle was fiddling with his salted fish in front of the door. When he saw Li Aiguo coming in, he greeted him, "Aiguo is back."

"I'm busy, Third Uncle." Li Aiguo didn't stop and walked straight to the backyard.

The third uncle scratched his head and looked at Li Aiguo's back: "Where did this kid get a puppy from?"

The third aunt came out with coal ash, dumped it into the flower bed at the door, and asked casually, "What puppy?"

"Didn't you see that a dog's head popped out of Aiguo's arms just now? It was a black and white spotted dog." The third uncle said, shaking his head: "People are just getting enough food to eat, and they are actually thinking about raising dogs."

Yan Jiecheng squatted beside him and brushed his teeth, spitting out the toothpaste foam: "Dad, Aiguo only earns a little over 100 yuan a month. I heard that the instant noodle factory also has benefits. How can we afford to raise a dog?"

"What do you know? I'm just worried that other residents might have complaints." The third uncle looked at Yan Jiecheng and said, "When you have time, give Aiguo a reminder. No matter if he listens to the advice or not, he should at least think well of us."

Yan Jiecheng gave a thumbs up and said, "Dad, you are still the cunning one."

"Hey, you little bastard, how could you talk like that to your father?" The third uncle picked up a broom and pretended to hit Yan Jiecheng.

Yan Jiecheng jumped up from the ground, turned around and ran away: "Dad, don't leave me lunch."

He ran away in a flash.

"This child is not at home during the New Year."

The third aunt was about to stop Yan Jiecheng, but the third uncle stopped her: "Don't worry about him, he must have gone to Yu Li's house to help his father-in-law chop firewood."

When talking about the matter between Yan Jiecheng and Yu Li, the third uncle also had a headache.

To be honest, the third uncle looked down on Yu Li because she didn't have a formal job.

But after the "Zhang Guifang" incident, the third uncle no longer dared to force Yan Jiecheng.

It would be troublesome if this guy really brought him a country wife.

At this time, Li Aiguo had already opened the door of his home.

Chen Xueru was making dumplings at home with He Yushui and Huang Sen.

Seeing Li Aiguo coming back, Chen Xueru hurriedly put down the dumplings, took out a towel to wipe her hands, and walked over to take the bag from his hand.

"Don't be anxious. There are several fish in here. We have to take them out quickly." Li Aiguo put the bag on the ground, opened the bag, and there were more than ten fish inside.

Yesterday at the fishing team, he gave the ten fish to Liu Hong and Chen Danian as a wedding gift. When they were leaving, the fishing team gave them more than ten fish.

It was the first time Chen Xueru had seen this kind of fish: "Brother Aiguo, what kind of fish is this?"

"Huangyu is a kind of fish grown on the plateau. It tastes very good." Li Aiguo said as he was about to hang the fish on the rope.

As soon as he bent down, Chichi in his arms was awakened by the teasing. He poked his little head out of his arms and looked around with his black little eyes.

"Oh, this, this, this." Chen Xueru was startled when she saw Chichi and quickly turned around and closed the door.

She leaned against the door and asked in a low voice, "Brother Aiguo, did you steal the panda from the zoo?"

He Yushui and Huang Sen were also shocked. They didn't even bother to make dumplings. They stood up and surrounded them.

Li Aiguo took Chichi out of his arms and explained, "This was given to me by an old hunter when I was in Sichuan Province. Its name is Chichi, and its parents are both gone."

Women are very soft-hearted. When He Yushui heard about Chi Chi's tragic life story, she couldn't bear it and hugged Chi Chi.

Huang Sen was also there helping Chichi take care of his hair.

Chen Xueru glanced at Chichi and whispered, "Brother Aiguo, this is a panda, not a dog."

Li Aiguo understood what she meant: "After the New Year, I will go to the zoo to ask if we can send the food there."

At this time, Chi Chi was having fun with He Yushui and had no idea that the nanny had decided to send it away.

"Chichi is only a few months old now and can only eat milk powder." Li Aiguo took out a few cans of milk powder from his bag, told Chen Xueru to take good care of Chichi, and then he was ready to go out.

Chen Xueru stopped him: "You just came back, why are you leaving again?"

"It's just a small matter. It won't take you long. Please save some lunch for me." Li Aiguo slung his canvas bag over his shoulder, pushed his bicycle and left the courtyard.

Professor Hua reminded him several times on the phone that he must send the manuscript over as soon as he returned to Beijing.

Li Aiguo also knew why Professor Hua was so anxious.

The sooner the proof process is verified, the sooner the paper can be invented.

What is the use of the geometrization conjecture as a part of the Poincare conjecture?

It doesn't seem to be of any use.

If anything, it proves that the Earth is a sphere, not flat, nor a donut.

At the same time, a generalized version of the geometrization conjecture also proves that no matter how strange the shape of the universe is, it must be composed of eight basic topological shapes.

Unlike practical technologies such as calculators and transistor chips, it seems to be useless and does not need to be kept secret at all.

However, worrying about whether solving difficult math problems is useful is meaningless in itself.

The reason why mathematics is so fascinating and attracts countless mathematicians to devote their energy is not necessarily because of how much economic benefit can be obtained by solving a formula, but because it is there.

From the perspective of the development of human civilization as a whole, human beings cannot just focus on the present, but must also look to the universe and the distance.

However, what Professor Hua, the Institute of Mathematical Computation, and the domestic mathematics community need now is to survive in the present.

Although the Chinese New Year is approaching, the Institute of Mathematical Computation remains open to the public as usual.

Because Li Aiguo had made an appointment with Professor Hua long ago and was still wearing a four-pocket shirt, he registered at the gate and went in.

Li Aiguo has the same feeling every time he comes to the Institute of Mathematical Computation. The air here seems to be filled with the scent of mathematical calculation problems.

Walking along the path, when we passed a boiler room, the door suddenly opened.

"I think I understand! I have to go ask Professor Hua for advice." Chen Zilan pushed the door open and walked out, head down. He stopped only after Li Aiguo called him twice.

Compared with a year ago, Chen Ziran has become much thinner and duller.

He stared at Li Aiguo for a long time before he managed to say, "Brother Aiguo, do you have another mission? I'm telling you, I can't do it this time. I have important work to do."

Li Aiguo wanted to explain, but after hearing this, he became interested: "Brother Chen, what new discoveries have you made?"

Chen Ziran looked around, came over mysteriously, and lowered his voice: "Does 1+1 know?"

Li Aiguo's eyes widened: "Goldbach's conjecture? Have you proved it?"

Chen Ziran didn't expect Li Aiguo to know this, and quickly waved his hand: "No, in fact, I am still far from 1+1, but I have a new idea about expressing large even numbers as the sum of a prime number and the product of no more than two prime numbers."

The table of large even numbers is the sum of a prime number and the product of no more than two prime numbers. That is 1+2. Li Aiguo could understand why Chen was so cautious.

"Have you proved it?" "It's not that easy. It's just an idea. An idea, do you understand? I'm going to find Teacher Hua now and don't want to talk to you anymore." Chen Ziliao became a little anxious when he mentioned work.

Li Aiguo took a few quick steps to catch up, "I also want to go see Professor Hua, let's go together."

Chen Zilan thought that Li Aiguo went to see Professor Hua because of something related to the railway and did not take it seriously.

He brought Li Aiguo to Professor Hua's office door, knocked, and waited for a response before pushing the door open.

"Teacher, I have a new idea."

As soon as he entered the door, Chen Ziliao handed the draft in his hand to Professor Hua.

Professor Hua took it and put it on the table. He looked at Li Aiguo and held out his hand: "You must be Comrade Aiguo. Professor Qin said you were very young on the phone, and I thought he was joking. It seems that young people are to be feared."

It was the first time that Li Aiguo met Professor Hua, a big name in domestic mathematics.

Compared with Professor Hua in newspapers and magazines in later generations, Professor Hua at that time was younger, with a tall and thin figure, a pair of black-framed glasses on his nose, and a sharp gaze behind the lenses.

He was wearing a washed-out navy blue Zhongshan suit, with the collar buttoned meticulously to just below his Adam's apple. His cuffs, though worn, were neatly rolled up, revealing his bony hands.

"Professor Hua, you are the eternal role model for us young people." Li Aiguo stretched out his hands and held Professor Hua's hands tightly: "Although Liangyuan is a good place, it is not a place to live for a long time. Let's go back! In short, we should go back to choose the truth; we should go back for the sake of our country and nation; we should go back to serve the people; even for our own future, we should go back as soon as possible!"

"Professor Hua, your "Open Letter to Chinese Students Studying in the United States" is so well written and has greatly inspired the spirits of us younger generations."

Professor Hua didn't expect that Li Aiguo could memorize his article completely. He nodded and said, "It's just some true feelings. But you, without saying a word, actually released a big satellite."

Li Aiguo said: "This is not just my achievement. Professor Qin and others also played a crucial role."

Professor Hua has a unique temperament as a researcher. He doesn't like to be long-winded. He asked directly: "Did you bring the draft?"

Li Aiguo took out the paper from his canvas bag and handed it over.

Professor Hua took it, sat on the chair, and began to study it carefully.

Chen Ziyuan realized at this moment that the train driver had come to ask the Institute of Mathematics for help. How could there be a mathematics paper?
Now Professor Hua is focusing all his energy on the thesis, and Chen Ziliao is a little anxious.

what happened?
Chen Zilan knew Professor Hua's temper and did not dare to disturb him. He could only stretch his neck and lean over to take a look.

He roughly understood that it was a topology problem, but when he read on, he didn't quite understand it.

On the one hand, Professor Hua's hand blocked part of the formula.

On the other hand, he studied number theory and knew a little about topology, but only the basics.

Just as Chen Ziyuan became more curious and was about to ask Li Aiguo what he was proving, Professor Hua moved his hand away and revealed the title of the paper.

On the validity of the Poincare conjecture in three dimensions

Poincare conjecture?!

Curiosity disappeared in an instant.

Here comes another madman.

Since the establishment of the Institute of Mathematical Computing, we have received submissions from the public from time to time.

What have proved the Goldbach conjecture, the Riemann hypothesis, and the Hodge conjecture? Even a while ago, when Chen Ziliang went out, he was stopped by an old man who took out the world's grand unified formula.

"I am so patriotic that I have become stupid even after studying mathematics"

Although this is not the direction of his research, don't think that he knows nothing about the Poincare conjecture.

For countless years, mathematicians around the world who study topology have studied the Poincare conjecture.

Did anyone succeed then?
No!

If you, a train driver, can prove it, that would be like seeing a ghost!
Complaining in his heart, Chen Zilan was about to remind Professor Hua not to waste time.

Professor Hua raised his head at this time: "Aiguo, where are you going to publish your paper?"

Li Aiguo nodded: "Your institute's Journal of Mathematics"

"Acta Mathematica Sinica" is the earliest professional mathematics journal in China. It was founded in 1936 and mainly publishes original and outstanding papers in pure mathematics and applied mathematics.

The current editor-in-chief is Professor Hua.

Although Chen Ziliao is the successor editor-in-chief, he has not yet published any weighty paper in the Acta Mathematica Sinica. When he heard Li Aiguo's words, he was shocked and was about to remind Professor Hua.

Before he could speak, he saw Professor Hua shaking his head: "Not appropriate"

Chen Zilan secretly breathed a sigh of relief and swallowed the words that were about to come to his lips.

Professor Hua went on to say: “Although Acta Mathematica Sinica is the largest mathematics journal in China, its platform is still too small in the world, which is not conducive to the promotion of papers.”

It was the first time that Li Aiguo heard such a term: "Promote the paper?"

Professor Hua also knew that Li Aiguo was not a professional researcher, so he patiently explained: "For a difficult paper like this to be published in a journal, it often needs to go through a long peer review process to verify whether the proof process is correct.

For papers involving proof of important conjectures, the review cycle is often longer.

Even if the paper passes the review and is published in a journal, it still takes a long process to quickly gain recognition from international peers. Sometimes, several international conferences have to be held for discussion.

If you want a paper like yours to be recognized by international peers in a short period of time, you need the endorsement of a well-known mathematics journal."

Li Aiguo seemed to understand: "You mean submitting it to a foreign journal?"

Professor Hua took out a cigarette from his pocket and handed it to Li Aiguo, then handed one to Chen Zihua, then lit one himself and took a puff. "I used to be a researcher at the Princeton Mathematical Institute, and I was a colleague of Mr. Eisenhart, the editor-in-chief of the Annals of Mathematics. His main research direction is topology, and he has also conducted in-depth research on the Poincare conjecture."

"Annals of Mathematics". One of the four major journals.

Professor Hua is indeed a big shot. He actually worked with the editor-in-chief of the Big Four.
Li Aiguo's heart trembled, but he quickly came to his senses: "Professor Hua, if the paper is submitted to a foreign journal, I need to report it to the organization first."

Professor Hua also understood the relevant procedures and nodded: "How about this, leave the paper here first, I will have someone review it first, and if you have any results, I will contact Mr. Eisenhart."

Professor Hua submitted his paper directly to the Annals of Mathematics, using his own academic reputation as a guarantee, so he naturally had to be cautious.

Li Aiguo chatted with Professor Hua for a while, then rode his bicycle to the weather station.

After he left, Professor Hua sat down and picked up the paper again.

Chen Ziyuan finally came to his senses and asked in surprise, "Teacher, is it really okay to write a patriotic essay?"

"I just took a quick look at it. Both the proof ideas and the theories of Li Aiguo and others make sense. If there are any problems, they are just some minor ones." Professor Hua held a cigarette between his legs and looked up at Chen's materials: "Xiao Chen, what can I do for you?"

"Ah, no." Chen Ziliao hid the manuscript with his ideas behind him.

Professor Hua: "Since you don't have any other work, I'll stay and help review it. The requirements of the Annals of Mathematics are very strict, and we can't make any mistakes."

Chen Ziran: “Ah”

*****
There was a lack of communication channels between China and foreign countries during those years, but normal academic exchanges were not interrupted.

In 1956, he participated in the "International Debate on Chinese Social History" in Paris, and discussed the issue of periodization of Chinese history with European and American scholars.

The All-China Federation of Natural Science Societies (established in 1950) carried out mutual visits and exchanges with the Association of British Scientists and the French Federation of Scientific Workers.

In 1951, he attended the th Congress of the World Association of Scientific Workers (WCAS).

In fact, in this era of reconstruction, the country needs to achieve good results internationally to motivate workers and scientific researchers.

but.

Be cautious in everything you do, this is Li Aiguo's principle of doing things.

After Li Aiguo returned to the weather station, the farmer was just about to go home from get off work. When he saw him coming, he opened the door again.

"Aiguo, Chinese New Year is coming soon. Your master's wife asked you to bring your children to our house to pay New Year's greetings on the third day of the New Year." The farmer sat on a chair, took out a white pack of cigarettes from the drawer and threw it to Li Aiguo.

"Save it for the New Year."

It is indeed a happy thing to have a big man as a teacher.

Li Aiguo put the cigarette into his canvas bag without hesitation, then sat down and talked about his plan to submit a paper to a foreign journal.

After listening, the farmer lit a cigarette and asked, "This should be Professor Hua's idea, right?"

Li Aiguo felt that he had been caught: "Professor Hua only brought this up out of consideration for me. He just asked for my opinion, but it was mainly my own decision."

Seeing that Li Aiguo was concentrating on carrying the burden for Professor Hua, the farmer said with a smile, "You, I still underestimate your teacher. If I were the kind of person who couldn't tell right from wrong, I wouldn't let you, a little guy, turn Factory 221 upside down."

Li Aiguo smiled and said, "Teacher, this is indeed my own idea."

He resolutely took the responsibility on himself, which not only did not make the farmer angry, but also made him feel relieved.

After all, no one likes dealing with two-faced people.

The farmer took a puff of his cigarette and said, "It just so happens that I have to go to the lake to attend a meeting tonight. The higher-ups are currently compiling this year's results. If your paper can be published in a world-class journal, it will be a small achievement. I believe the higher-ups will agree."

Li Aiguo was naturally very grateful when he saw that the farmer was willing to come forward in person.

"Don't thank me. Come early on the third day of the Chinese New Year and help me cook. That's worth a thousand thanks." The farmer said as he stood up, sent Li Aiguo out of the office, and went to the lake.

Things turned out just as the farmer expected. After learning the whole story, the higher-ups gave the green light without hesitation.

They even sent translators from the foreign affairs department to the Institute of Mathematics to assist Professor Hua in his work.

The paper was sent to the other side of the ocean via Hong Kong.

After finishing all these things, it was already New Year's Eve. Li Aiguo bought some melon seeds and candies and returned to the courtyard humming a little tune.

As soon as I entered the door, I saw Jia Dongxu and the staff of the street office standing at the door of my house.

"Secretary Zhang, Li Aiguo is feeding the dog with milk powder!"

(End of this chapter)