Madman and Genius

At two in the morning in Upper Manhattan, a McDonald's remained lit, still open for business.

In the innermost booth of the dining area, three people sat together. The professor sat across from Lin An, holding a cup of hot coffee with a half-eaten burger in front of him.

Darnell had already finished two burgers and was currently tackling his third order of fries, the crunching sound exceptionally clear in the quiet shop.

Lin An was holding a cup of black coffee, sipping it slowly and with the elegance of a young nobleman.

The three of them remained silent for a long time.

Darnell was busy eating as if he would starve to death if he slowed down, Lin An had no desire to speak, and the professor was still processing everything that had just happened...

Kidnapping, smoke bombs, beatings, murder, and then, when the sirens wailed, this young man had led him out the back door, through three alleys, and into this fast-food joint.

Robert was wondering why he had run away in the first place.

He was the victim; when the police arrived, he could have simply told them he had been kidnapped by four men and rescued by two passing youths.

Then, that would have been the end of it... He was a professor at Columbia University, and the mysterious death of four thugs was a trivial matter that wouldn't have been a problem for him at all.

Why, then, had he run?

[Because this old fart cares too much about his reputation; I was his student back in '09.]

[How much does he care about his reputation?]

[The old man is a leader in the field of financial engineering, and his face is his life. Once, he didn't zip up his fly during a lecture; the moment he realized it, he ended the class immediately and sent an apology letter to every student who had been in the room.]

[Ah, that is way too much face.]

[Exactly, so he would never let anyone know he was kidnapped and nearly sodomized. It would make him the laughingstock of the academic world until the day he died.]

The professor took a deep breath, set down his coffee cup, and looked up at Lin An.

"Speak. What do you want from me?"

Lin An picked up his coffee cup, took a sip, and set it back down.

"I want to be your student."

The professor was stunned.

"What?"

"Your student."

Lin An repeated himself.

"A doctoral candidate, just a name under your roster. I don't need to attend classes, and I don't need your guidance. I just need a status... the status of a student at Columbia University."

The professor stared at Lin An for five seconds, his brow furrowing.

His brain was racing... A young man who had killed four people without changing his expression now wanted to be his student?

This wasn't right.

There had to be something wrong here.

"What do you need a student status for?"

The professor's voice turned cautious.

"Are you trying to use my reputation to launch some financial project?"

He had seen too many people like this... hanging onto his name, borrowing his resources, and then running gray-market financial products on Wall Street. When they made money, they claimed to be his students; when things went wrong, they distanced themselves from him.

Not long ago, a former student had opened a company on Wall Street using his name, only for the company to go bankrupt after he exposed them.

Lin An shook his head.

"No."

He paused.

"I want to use your student status to secure my own identity."

The professor didn't understand.

"What do you mean?"

Lin An leaned back in his chair, crossing his hands on the table and interlocking his fingers.

"I have no memories of my past, and I haven't found any identification documents—no passport, no driver's license, no social security card, nothing."

His tone was calm, and he spoke the lie that sounded like the truth without changing his expression.

"I must be an undocumented person. I have no status in the United States, so I can't do anything. That is why I want to become your student, to obtain a legal identity."

The professor scratched his head, not knowing what to say.

He had lived for over sixty years and taught in Massachusetts for over thirty, meeting all kinds of students, but he had never encountered anything like this.

A man kills four people, then sits down and calmly says, "I want to be your student because I don't have an ID card."

This wasn't just absurd.

This was insanity.

The professor looked at Lin An's face... young, delicate, a faint smile hanging at the corners of his mouth, his eyes as calm as a stagnant pool of water.

He looked perfectly normal.

No, that wasn't right.

He looked too normal.

A normal person shouldn't behave like this after killing someone.

The professor defined Lin An in his heart... this was a psychopath.

The corner of his mouth twitched.

He wanted to say "Are you crazy?", but he didn't dare.

The professor swallowed a mouthful of saliva, picked up his coffee cup to take a large gulp, set it down, and cleared his throat.

"Uh... sir?"

"Just call me Lin An."

"Very well, Lin An."

The professor adjusted his posture to make himself look more natural.

"You said you wanted to be my student, so you should know that a doctoral candidate at Columbia University isn't something you can just become. You need an undergraduate degree, you need GRE scores, you need letters of recommendation, you need to pass an interview..."

"I know."

Lin An interrupted him.

"But I feel that I am a good student. I am qualified to be a doctoral candidate at Columbia University."

Darnell's action of chewing his fries paused, he looked up at Lin An, then lowered his head to continue eating.

The Bullet Screen was scrolling frantically.

[Hahahaha, streamer, what did you just say???]

["I feel that I am a good student"]

["I am qualified to be a doctoral candidate at Columbia University"]

[Is this the legendary "confidence is the peak"?]

[Columbia University: Who are you?]

[Streamer: I am your father]

[The professor's expression is killing me, his mouth won't stop twitching]

[Professor: I want to curse at him, but I'm afraid he'll kill me]

[Professor must be thinking right now: This guy is a psycho, but I can't say it out loud]

Lin An ignored the Bullet Screen; he looked at the professor, the smile on his face unchanged.

The professor was silent for a few seconds, then nodded.

"Fine, since you put it that way, let me test you."

His tone was very polite, like an old professor chatting with an interested student.

"What is your name?"

"Lin An."

"Is Lin An your Chinese name?"

"I suppose so."

"Suppose?"

"I told you, I don't have my previous memories. The name Lin An is one I came up with myself."

The corner of the professor's mouth twitched again.

"Alright, Lin An, since you want to be my student, let me ask you a few basic questions."

He thought for a moment, then opened his mouth to ask.

"What is the Fundamental Theorem of Calculus?"

The Bullet Screen began to flood with answers.

[Fundamental Theorem of Calculus: If a function f is continuous on the closed interval [a,b] and F is the antiderivative of f, then ∫_a^b f(x)dx = F(b)-F(a)]

[Wrong, that's the second fundamental theorem]

[The first fundamental theorem is: If f is continuous on [a,b], then F(x)=∫_a^x f(t)dt is differentiable on [a,b], and F'(x)=f(x)]

[Just say both, to be safe]

Lin An glanced at the Bullet Screen, then looked up, his expression returning to calm.

"The Fundamental Theorem of Calculus is divided into two parts."

He began to speak.

"Part one: If function f is continuous on the closed interval [a,b], then the function F(x)=∫_a^x f(t)dt is differentiable on [a,b], and F'(x)=f(x)."

He paused for a moment.

"Part two: If f is continuous on [a,b] and F is any antiderivative of f, then ∫_a^b f(x)dx = F(b)-F(a)."

The professor's eyes widened slightly as he continued to ask.

"In linear algebra, what are eigenvalues and eigenvectors?"

The Bullet Screen began to scroll again.

[This is simple, chapter one of linear algebra, watch me...]

Lin An repeated the answer from the Bullet Screen.

The professor's expression changed.

"In probability theory, what is the content of the Central Limit Theorem?"

The Bullet Screen scrolled even faster.

[This is the cornerstone of probability theory, very important, watch me...]

Lin An repeated it.

The professor nodded and asked again.

"In financial mathematics, what is the Black-Scholes formula?"

The Bullet Screen fell silent for a second, then began to output frantically.

[The Black-Scholes formula...]

Lin An watched the Bullet Screen, repeating it word for word.

He spoke very slowly because the Bullet Screen was scrolling too fast, and he needed to read and memorize it simultaneously.

But he was very accurate; every symbol, every variable, and every formula was perfectly correct.

After listening, the professor fell silent.

He stared at Lin An for a full ten seconds, then leaned back in his chair, crossed his hands over his chest, took a deep breath, and slowly exhaled.

"Have you studied these before?"

"I don't remember."

"Then how do you know them?"

"I don't know."

Lin An said.

"But I know that I can do it."

The professor suddenly felt a sense of regret; what a good student, why did he have to be a madman?

It was such a pity.

The professor sighed.

"Lin An, your answers are all correct."

He paused.

"Your foundational knowledge is very solid, at least... at least no worse than the first-year doctoral students under my supervision."

Darnell interjected from the side.

"So professor, can you help him obtain an identity?"

The professor looked at Darnell, then at Lin An.

"I can try, but it will take time, and I need you to provide your fingerprints. I will use them to search the database to see if there is any record of you.

Perhaps you applied for a visa in the past, or perhaps your fingerprints are in some system; we might be able to find your identity information."

Lin An nodded.

"That's fine."

"Also."

The professor paused.

"You need a name, not Lin An, but a legal one that can be used on documents. Your real name from before, or... a brand new name."

"Just use Lin An."

"Lin An is a Chinese name, the pinyin is Lin An?"

"Correct."

"Then your surname is Lin, and your given name is An?"

"Correct."

The professor nodded, took a small notebook and a pen out of his pocket, and wrote down the name.

Darnell leaned back in his chair, arms crossed, watching the professor write before turning his head to look at Lin An.

"Bro, that stuff you were talking about earlier—calculus, eigenvectors, the Black-Scholes model—do you actually know that?"

"Didn't I just answer those questions?"

"I mean, do you actually understand that stuff, or did you just memorize it?"

Lin An thought for a moment.

"I'm not sure."

"You're not sure?"

"Right, I'm not sure if I understand it or if I just remember it. But I feel like I understand it."

Darnell was silent for two seconds, then shook his head.

"Bro, you are such a strange person. You don't even know who you are, but you know calculus. You don't know if you've ever been to college, but you know things taught to PhD students. You don't even know if you have a passport, but you know how to kill."

"Does that matter?"

"Bro, if that doesn't matter, then what does?"

"Happiness is what matters most."

The professor listened to this conversation from the side, saying nothing.

He lowered his head, looking at the name written in his notebook... Lin An.

Then he wrote a small line of text beside it: High intelligence, high functioning, memory loss, potential severe mental issues, psychological evaluation recommended.

But he didn't say these words out loud.

Because he knew this young man would not accept a psychological evaluation.

Besides, he didn't dare to bring it up.

The professor closed his notebook, put it back in his pocket, and looked up at Lin An.

"Lin An, I will help you, but you have to help me too."

"What is it?"

"About what happened tonight, I need your guarantee that no one will find out."

Lin An smiled.

"Professor, nothing happened tonight... Do you need me to check who was responsible for this?"

Lin An shook the phone in his hand; it was something he had taken from the corpse, and he hadn't looked at it yet.

The professor stared into Lin An's eyes for three seconds, then nodded.

"Fine."

He stood up, took off his overcoat, and handed it to Lin An.

"Returning your coat."

"You keep it, it's cold outside."

"No need, I'm taking a cab back. It's only a few steps from the door to the car."

Lin An didn't decline further, taking the windbreaker and putting it on.

Darnell shoved the last few fries into his mouth, stood up, and brushed the crumbs off his body.

"Bro, how are we getting back?"

"Cycling."

"Are you sure? It takes over an hour to bike from here to Jamaica."

"Didn't you say you had good stamina?"

"I said I could ride fast, not that I wanted to ride for a long time."

"Then just think of it as exercise."

Darnell took a deep breath and let it out slowly.

"Bro, meeting you is the greatest... challenge of my life."

He had originally wanted to say "disaster," but changed it to "challenge" at the last second.

Because he felt that saying "disaster" in front of Lin An wouldn't be appropriate.

The three of them walked out of the fast-food restaurant.

In the early hours of Manhattan, the air was as cold as a knife, stinging their faces.

Streetlights flickered overhead, and the distant skyline was dyed orange by the city lights, hiding the stars.

Darnell straddled the Roadster Bicycle, gripped the handlebars tight, and placed his feet on the pedals.

Lin An sat on the back seat, one hand resting on Darnell's shoulder.

The professor stood at the entrance of the fast-food restaurant, watching them.

"Lin An."

He called out.

Lin An turned his head back.

"Tomorrow at three in the afternoon, come to my office, Mathematics Building, fourth floor, Room 412."

"Alright."

Darnell pushed down on the pedals.

The Roadster Bicycle surged forward, its tires making a rustling sound against the asphalt road.

The professor stood at the entrance of the fast-food restaurant, watching the bicycle gradually move away and disappear around the corner of 110th Street.

He stood in the cold wind, recalling a sentence Lin An had said... "I am the messenger sent by God to save you."

The professor shook his head and gave a bitter smile.

God would not send a murderer to save him.

Unless...

God himself was a madman.

The professor turned and walked into the fast-food restaurant, sat down at the counter, and ordered a cup of hot coffee.

He needed to think carefully about how to deal with this madman tomorrow.