我和Nobelium的这些年 第4章 Chapter 4

Upon graduation,

Yu smoothly passed the judicial examination and joined a law company, while Nuo successfully obtained a high school teacher qualification certificate and passed the recruitment assessment for a high school teacher position.

Both majors coincidentally had their graduation photo shoots on the same day.

After Yu took the group graduation photo, he headed straight to University C’s library after taking some commemorative photos with a few good friends in the hall.

When he arrived, Nuo was already waiting at the entrance, also dressed in academic gowns.

He wore pink trim, while Nuo wore blue trim.

"Red and blue have always been a perfect match," Yu thought to himself.

"I didn't expect you to look scholarly in an academic gown," Nuo joked as he straightened Yu's slightly crooked bow tie.

"As a law student at University A, I can't let down the face of the Math Department's Nuo at University C," Yu teased.

Inside the library, many graduates in academic gowns were capturing memories in their respective corners.

Yu and Nuo made their way to the second section of the sixth row of shelves in the European Literature area on the third floor of the library.

"Fortunately, no one has borrowed this book," Yu said as he pulled out Selected Kafka Short Stories.

It was the book he had asked Nuo to borrow, with the code E211-602-312.

Certainly, no one had borrowed it since he had just returned it in the morning, Nuo felt a tad smug.

"I really want to take it home, frame it, and hang it on the wall," Yu said as he flipped to a certain page, his gaze fixed on it, softening his jawline.

On page 34, at the top blank space, someone had written with a pencil: 2013-04-24.

It was the day they met.

"When did you write this?" Yu asked.

Below the blank space, a set of formulas had been added: x? y?=1.

"I told you about this formula the day after I wrote it," Nuo admitted, "I found it when I returned the book that day, and since then, I've been carrying it with me. I just returned it this morning."

Anyway, he blushed after speaking.

"x? y?=1," Yu lightly traced with his fingertip, caressing the formula with a soft voice as if kissing the earlobe.

"This is the most beautiful love words I've ever heard."

Nuo blushed even more.

"Here," Nuo placed his palm on the book and then moved it away, "your graduation gift."

A simple ring with the inscription inside: x? y?=1.

Yu was astonished, his gaze lingering on the ring.

— On the night we were together, on the way back, I asked Nobelium, 'What does x? y?=1 mean?'

"I'll tell you when we get back," Nobelium replied.

After returning to the dorm, I received a WeChat message from Nobelium.

The first message was a picture.

It was a proof process of a theorem about F(x,y)=0.

The process was too complex, I only remembered the conclusion Nobelium wrote at the end.

Conclusion:

1. For the function F(x,y)=x? y?, the collection of all solutions to the equation F(x,y)=1 forms a unit circle.

2. Therefore, for the function F(x,y)=x? y?-1=0, if it satisfies:

1) F(x0,y0)=0;

2) F(x,y) is continuous in the closed rectangle D and has continuous partial derivatives;

3) Fy(x0,y0)≠0

Then, y=f(x) is the unique implicit function for F(x,y)=x? y?.

Following that, Nobelium sent another WeChat message.

He said, "The implicit function theorem, when certain conditions are met, can be used to describe whether there exists an explicit relationship between certain variables. Its unique existence theory made me realize that you are my unit circle. Necessary and sufficient."

You are the necessary and sufficient condition for my transformation to a gay, the unique condition.

— Until now, I still think that this unique romantic gesture was from the Little Prince.

Yu later mentioned this in his posts.

While Yu was still lost in thought, Nuo put the ring on his middle finger.

"I," Yu looked at the ring on his hand and couldn't help but smile, "we are truly meant to be together... till old age."

With that, he took out a ring from his pocket.

The ring on his finger now is exactly the same as the one he wore before. The only difference is that one side of the pair of rings is engraved with "130424 F&W," while the other side is inscribed with "x? y?=1."

The two of them couldn't help but smile at each other.

It turns out that they both anticipate and are certain about the future.

Both sets of rings are from the "Gold Wedding Ring" series designed by Torafu Architects in Japan. The rings in this series are coated with a layer of silver, and as time passes, the gold material underneath will gradually be revealed. The more gold is revealed, the longer the marriage, symbolizing that love grows stronger over time.

"Just wait for me a moment," Yu said as he walked to the back to tidy up the staff who were collecting returned books.

When he returned, he had an extra pen in his hand.

Along the edge of this page, he vertically wrote: 2015-05-28, F&W. The two of them looked at each other and placed the book back on the shelf.

On May 28, 2015, Yu and Nuo graduated.

Graduation will be good because you are still here.

The seasons will be good because you are always there.

Before leaving the library, Nuo asked a passing female student to take a photo of the two of them. They stood back-to-back, wearing bachelor's gowns, fingers interlocked, with their pure silver rings touching. On their shoulders, the book Selected Kafka Short Stories with the number E211-602-312 was visible.