Before going to bed at night, Shen Qi received a WeChat message, sent by Xu Rui.

Xu Rui has been in the capital for almost a week, he broke into the men's 100-meter run final of the National U19 Track and Field Games, and Xu Rui will participate in the men's 100-meter final at 6:30 p.m. tomorrow evening.

Shen Qi knew that this 100-meter final was very important to Xu Rui, which was related to Xu Rui's future.

"Tomorrow at 18:30, I will be on time to witness you win the 100-meter championship. Shen Qi replied with a message, and then went to sleep.

The next day, the teaching of the math camp continued.

The teacher is Qian Fang, who teaches the section of ordinary differential equations.

Except for Shen Qi, the other 25 students were all listening to the lectures in the classroom.

Shen Qi was called to a twenty-square-meter room alone, just him and Sun Erxiong.

The room was very messy, and there was white paper everywhere on the table and floor, most of which had mathematical symbols written or geometric figures drawn on the paper. All kinds of math books were scattered in all corners in a disorderly manner, and rulers and compasses could be seen everywhere, bang, Shen Qi kicked a ruler as soon as he entered the room.

It was broad daylight, but the curtains in the room were impermeable, and the only electrical appliances in the room were fluorescent lamps hanging on the ceiling.

In the corner of the wall stands a small blackboard, and white chalk leaves a mark on the blackboard, which is a painting.

The painting is composed entirely of straight lines, and when viewed from a vertical blackboard, a corridor with a large door extends infinitely, and the floor is staggered with black and white, like countless chess boards lined up.

The first time Shen Qi saw this pattern, he never left the blackboard.

The smell of smoke in the room was very strong, Sun Erxiong snuffed out the Zhongnanhai cigarette between his fingers, and asked Shen Qi: "What is the level of this painting?"

"Mr. Sun, I don't know much about art, so I can't give an evaluation from the perspective of painting art, but from a geometric point of view, I like this painting on the blackboard very much. In my understanding, this painting seems to be a cross-section of the projection line, its composition is all straight lines, and the simplest lines outline the most complex existence. Shen Qi said.

"Looks like you've learned perspective. Sun Erxiong smiled kindly, "Outstanding painters must have a deep understanding of geometry, such as Leonardo da Vinci, Dürer and Alberti, but on the other hand, do outstanding geometricians all paint? Well, I think so." Shen Qi, do you know how to draw?"

Shen Qi shook his head: "No, no, I'm not a scholar, at most I can doodle, draw an emoji or a two-dimensional cat-eared girl or something." ”

"Okay, sit. Sun Erxiong invited Shen Qi to sit down, and said, "Officially, in addition to the instructor of the mathematics camp, I am also a professor in the Department of Mathematics of Yan University. ”

"Hello Professor Sun. ”

"Shen Qi, do you know why I called you over alone?"

"Tell me about your life ideals?"

"Of course, the ideal of life and the correct three views will be discussed with you. Sun Erxiong took out a magazine from a pile of waste paper and said as he flipped through it: "Shen Qi, a journal sponsored by CUHK, has published a professional mathematical paper in this journal, and the title of the paper is "Some New Solutions for Linear Nonhomogeneous Differential Equations with Constant Coefficients of the Second Order". ”

"The class has an axe, and I laugh and laugh. Shen Qi was a little embarrassed, in front of the professor of the Department of Mathematics of Yan University, his conventional mathematics paper on ordinary differential equations was not a great achievement, and it was even a little low.

Sun Erxiong closed the magazine and asked, "Shen Qi, let me ask you, are you a student of CUHK or Yan University?"

Shen Qi resolutely stated: "Of course I am a student of Yan University. ”

"Then why are you so indifferent to Yanda when you submit articles to a magazine sponsored by CUHK?" Sun Erxiong's face sank.

Shen Qi was still wronged: "I'm ...... My level is limited! "Mathematical Research" is so high-end, I am not qualified to submit it. "Mathematical Research is a mathematics journal sponsored by Yan University, which is among the top in the domestic mathematics community.

"Hehe, don't be nervous if it's okay, I'm joking, there is still a gap between the mathematical strength of CUHK and our Yan University. Sun Erxiong was instantly happy, "Of course, with Shen Qi's current level of mathematics, it is still difficult to get "Mathematical Research" to accept your manuscript. But don't be nervous, after all, you're only over 17 years old and less than 18 years old, so young, the future is limitless. ”

"Shen Qi, you see, the other students are all receiving Xiao Qian's lectures and studying differential equations in depth, and you have published papers on differential equations in professional mathematics journals, so you don't need to listen to Xiao Qian's lectures. Sun Erxiong said, "So I called you over alone, and I want to have a long talk with you, about life, about ideals, and about your understanding of mathematics." ”

"That's great, Professor Sun, Maxima often has, but Bole doesn't. "Shen Qi likes to communicate with professionals about academic issues.

"Your kid must have a perfect score for his essay, hahaha. Sun Erxiong stroked his palms and laughed, looking at Shen Qi more and more pleasing to the eye.

After laughing, Sun Erxiong asked, "Have you had breakfast?"

"Eaten, soy milk fritters. ”

"Have you eaten enough?"

"I was full, I ate six fritters and drank three bowls of soy milk, and the preferential breakfast of Yonghe soy milk at the school gate was particularly affordable. ”

"When you are full, do the questions, eliminate food and strengthen the stomach, which is conducive to the vigorous growth of teenagers in the adolescent period. ”

"......" Shen Qixin said, why are all professors in the world a routine?

Sun Erxiong walked to the small blackboard, picked up the blackboard to erase the chalk patterns on the blackboard, and then picked up a piece of chalk to make a new picture.

Sun Erxiong's geometric drawing skills are very solid, and he can draw a standard circle without using a compass, at least to the naked eye.

Immediately afterwards, Sun Erxiong casually made a few straight lines, and did not use a ruler, just pulled out a straight straight line.

Six straight lines form a hexagon, which is enclosed in a circle.

The six points connected by the hexagon and the circle are marked by Sun Erxiong as A, B, C, D, E, and F respectively.

"Do you understand?" Sun Erxiong asked Shen Qi.

Shen Qi nodded and shook his head: "In the sense of Euclidean geometry, I understand, but in the field of non-Euclidean geometry, I can't understand it, because the conditions given by Professor Sun are not sufficient, I don't know what Professor Sun wants me to do?"

"Hehe, it's good if you don't understand. Sun Erxiong smiled habitually, and then continued to draw.

In the right margin of the circle and its inner hexagon, Sun Erxiong made three new straight lines, and the three straight lines intersected at one point, and this point was marked by Sun Erxiong as L.

"Based on this pattern on the left, you give me the pattern on the right completely, I don't care if Shen Qi you use Euclidean geometry or non-Euclidean geometry, all I want is a correct answer. Can you do it, Shen Qi?" Sun Erxiong asked with a smile.

Shen Qi's eyebrows were twisted into Sichuan characters: "Give me some time, Professor Sun, I'll do my best." ”

"Don't be nervous, time and this room are yours, and you can use any of the drawing tools and references in this room. Okay, I'm going to buy pork, by the way, Shen Qi, do you like celery-stuffed dumplings or Chinese cabbage?" Sun Erxiong stuffed the wallet on the table into his pocket and prepared to withdraw.

"Whatever. Shen Qi's eyes were fixed on the blackboard, and he dealt with the two words absentmindedly.

Sun Erxiong was unhappy: "You can do the question casually, but you must not eat dumplings casually!"

Shen Qi: "Is it okay to have dumplings stuffed with leeks and shrimps?"

"Wait, I'll go to the vegetable market to buy ingredients, and we'll eat dumplings stuffed with leeks and shrimp at noon." Sun Erxiong was happy, so he left the house to buy vegetables.