Enter the Immortal Cultivation

In the sunshine, the alpine dwarf pines cast delicate shadows. On a rock in front of a dwarf pine, the girl rested on the boy's knee, and the boy read quietly. It was a peaceful scene. Then, the curious and playful boy quietly opened the girl's hair...

This is a youth campus love story with a normal style.

Most girls like stories like this. Although Chen Youjia is from Wanfa School and has a bit of a weird temperament, she is also a girl, so she naturally likes this kind of scene.

Therefore, she was still very coy when she was on Wang Qi's knee.

However, Wang Qi's breathing was always calm. Listening to the breathing and breathing of the young man behind him, Chen Youjia's own heart gradually calmed down.

"What are you studying recently..."

Wang Qi's hand slowed down for a moment, and he replied calmly: "A little thought about symmetry."

"symmetry?"

"Didn't I help people do some research on kink theory for a period of time? That's how I learned about it." Wang Qi said while using magic power to comb Chen Youjia's hair: "This is actually a quite interesting concept."

"group?"

Wang Qi nodded: "Even the monks in the Qi training period know how to use the concept of 'group' to express the martial arts they have learned in a completely different form, but few people are willing to work hard to understand this." The mechanism inside..."

Chen Youjia rarely smiled: "You are talking about yourself, how can an ordinary disciple in the Qi training period do this?"

"Hmm... I know two people from the Bo family. Is it possible to do it?" Wang Qi also smiled: "Actually, I relied on being familiar with the concept of groups at the time, so I completed this step using what was in the textbook. . Now I use less fists and kicks, but I gradually understand the truth behind it. "

"'Symmetry operation'." Chen Youjia rubbed his forehead: "It's pretty awesome."

Through the concept of "symmetry operation" in group theory, changing the various "forms" in a martial arts into another form can change the appearance of the martial arts without changing its meaning.

This is the characteristic that never changes away from its origin.

"Symmetry operation" is an extremely broad concept. It specifically means that a symmetrical image is an image restored after more than one action that does not change the distance between any two points, and each action can restore a symmetrical image. To put it simply, a square table has four symmetry operations: "rotate 90 degrees", "rotate 180 degrees", "rotate 270 degrees", and "rotate 360 ​​degrees".

Except for the "identity symmetry operation" of "rotation by zero degrees", the set of all other symmetry operations can be called a "group".

Groups are used to describe symmetry.

However, Chen Youjia was a little strange: "Well, I remember what idea you used before...complex form or...high-order polynomial?"

"Ah, this time I'm trying to use a very intuitive way. Symmetry operations are really interesting," Wang Qi said: "Even number theory can be viewed this way."

"Well, irrational numbers..."

Not all numbers can be expressed intuitively as the ratio of two integers. Similarly, not all irrational numbers can be intuitively written as "root two". "One plus root two" is also an irrational number.

No matter what common operations are performed on this irrational number - addition, subtraction, multiplication, division, you will get an irrational number in the form of "any number plus any multiple of the root of two".

This can be considered a property that rational numbers do not possess. This is also a special kind of "symmetry".

Symmetry here refers to the rule of using a new number to assign a value to any existing number - that is, the rule of changing any number into other numbers. This rule is even compatible with basic arithmetic rules such as addition, subtraction, multiplication and division.

"Finally, I'm ready to get involved in number theory..." Chen Youjia didn't move his head and shoulders, stretched his hand back, and patted Wang Qi's thigh: "What are you going to do? Leader of Li Zong?"

"Don't hurt me, I know I can't do this yet." Wang Qi replied: "I'm not interested in number theory in a short time. I just thought of it when I was thinking about 'symmetry'."

"Well……"

The two of them just quietly exchanged some arithmetic topics.

Until Chen Youjia heard a "rustling" sound in his ears.

"What are you writing with pen and paper?"

"Your hair...I have to record it."

Chen Youjia finally noticed something was wrong.

Is Wang Qi such a disgusting person?

Obviously not.

He is a scumbag who has to use game theory to analyze the pros and cons of falling in love.

Would a scumbag with this kind of game theory etched into his head do something so romantic and disgusting?

Obviously impossible.

Therefore, there is only one truth...

Chen Youjia formed a water mirror in front of herself, and the mirror reflected her current appearance - a bird's nest on her head. All her hair was divided into small strands and formed into weird links on her head.

Of course, it’s very artistic.

In addition, Wang Qi's face with pure eyes and a mean smile was also reflected in the mirror.

"Wang Qi..." A murderous intention emerged spontaneously. Wang Qi consciously put down his hair, then grabbed the pen and paper floating beside him and started recording quickly.

"Now... it's too late!" Chen Youjia turned her elbow back without hesitation, intending to teach this bastard a lesson with an elbow. Wang Qi was still writing something quickly with both hands, using only his elbows to defend himself against the enemy. As soon as their elbows touched lightly, Chen Youjia felt that the power in his arms had lost control. The originally docile good horse suddenly turned into a fierce horse, and its position was completely confused.

——I am obviously in a favorable position... Hell, just as he said, he has relaxed his fists and kicks now, but because of his arithmetic skills, he has understood many martial arts principles that he had never understood before...

Chen Youjia suddenly understood the difference between the two. But when her temper got stronger, she didn't want to admit defeat, and her arms suddenly danced like butterflies, bumping back and forth over and over again. Wang Qi still used his elbows to defend against the enemy. He just twisted left and right to block or avoid Chen Youjia's every attack.

Chen Youjia felt even more bitter when he saw Wang Qi writing furiously. She jumped out of Wang Qi's arms and beat him with some real fists and kicks. Wang Qi, however, showed no shame and just rolled around on the rocks, still not giving up writing.

Chen Youjia was really annoyed. He took out the scabbard and shouted: "Wang Qi!"

Wang Qi stopped immediately - but he was still writing in his hand.

"Let me fight immediately, otherwise..."

"Wait until I finish writing this line!" Wang Qi accelerated his hand speed. After a few seconds, he threw away the pen and paper: "Come on, use force! But don't slap your face..."

"What a beautiful idea!" Chen Youjia slapped Wang Qi's face with his scabbard without hesitation.

Then, the eye circles turned red.

Seeing that Chen Youjia was really angry and turned around, Wang Qi sighed: "Well..." He gently hugged the girl and pressed her lips with both hands: "Who wants you to be so strong? It hurts...I told you not to slap me in the face."

"I've become more capable." Chen Youjia wiped the corner of his eyes: "I actually practiced the Arrow Control Technique to the point of showing my face..."

Chen Youjia was completely unprepared for Wang Qi's hand just now. He was caught off guard, and his hand suffered twice the force before he felt pain.

Fortunately she is a monk. For a normal person, the tiger's mouth would probably burst open at this moment.

"My abilities have been growing..." Wang Qi's tone softened a bit.

"There is something wrong with you...idiot...idiot...you actually used my hair to make braids..." Chen Youjia's voice became lower and lower: "That's not what you meant..."

A braid group is a finite generating group that satisfies certain braid relations. It has a relatively intuitive expression method. Suppose there are two fixed boards with the same number of nails on each board. Each nail is connected to any nail on another plate with a thread. All thread segments can be entangled with other threads in any way, but they must not be twisted or knotted by themselves. Each nail can only be connected to one thread. The collective name for all the lines between these two plates is "braid" or "braid" in the mathematical sense.

The study of the addition and changes between these "braids" is the "braid group".

"I just wanted to visually see what the braid group looks like... Ah, and then I thought of the symmetry operation of the braid group, and the addition of the braid group - that is, the technique of knotting the braids together..." Wang Qi also felt quite embarrassed: "Well... you were asleep, so I just moved my hands a little bit. In fact, your hair is pretty, so I couldn't help but..."

"Do I have to play with you because my hair looks good?" Chen Youjia inexplicably felt better because of the last sentence: "You... say it again."

Wang Qi had no choice but to speak louder: "When you fell asleep, I just touched you..."

"Describe the psychological processes involved in committing a crime."

"Actually, your hair is pretty, so my hands are itchy." This time it was Wang Qi's turn to feel ashamed of himself - for a guy who has always been shameless, this experience was still new.

Chen Youjia finally calmed down. She stamped Wang Qi's foot hard: "I don't want to quarrel... I'll let you go this time... but be careful in the future."

"Huh... Thank you so much, junior sister, for your generosity..." Wang Qi was filled with gratitude.

"Untie me..." Chen Youjia said bitterly. She carefully examined her hair with her spiritual sense and found that it had been tied by a "cheap" guy with at least a thousand knots. Each knot was in a different link. These links were arranged according to the braid group. They all change and overlap...in short, they are as complicated as they are. Chen Youjia couldn't solve it by himself.

Since Wang Qi helped Chen Feng study the knot theory not long ago, his knot-tying skills are really good and invincible.

It is obviously impossible for Chen Youjia to cut off her hair - although she can indeed regenerate her hair in a short time. However, it would be nice to give Wang Qi a try. (To be continued ~^~)