They're already in university, and the primary school system is only just starting out?

Not long after Liang Tianshi hung up the phone, his phone chimed with a notification that he had received several pictures from his grandson, Liang Xiaodong.

He put on his reading glasses and brought the phone screen closer.

The image was clear, but the dense text and mathematical symbols made it difficult for someone his age to read on the small phone screen. He clumsily swiped and zoomed in on the screen, his brow furrowing slightly.

"This is too tiring for my eyes to look at," he muttered to himself, then pressed the internal phone on his desk.

"Xiao Cai, come in here for a moment."

The door was gently pushed open, and a shrewd and capable young secretary walked in.

"Old Liang."

"Okay," Liang Tianshi pointed to his phone, "I received a few pictures on WeChat. Could you enlarge and print them out for me? A4 paper will do."

"Yes, Mr. Liang." Secretary Xiao Cai responded crisply, took a few steps forward, and skillfully began to operate the equipment.

A moment later, accompanied by the soft hum of the printer, three A4 sheets of paper, still slightly warm, were delivered to Liang Tianshi's desk.

Xiao Cai neatly arranged them, respectfully handed them to Liang Tianshi, and then quietly withdrew, considerately closing the office door behind him.

The office returned to silence, with only the central air conditioning quietly delivering cool air.

Liang Tianshi spread the printed papers on the table, his gaze first falling on the top of the first page.

[Given that non-negative numbers a, b, c, d satisfy a + b + c + d = 6, prove that: (a - b)(a - c)(a - d)(b - c)(b - d)(c - d) ≤ 27]

With just a glance, Liang Tianshi's eyes narrowed slightly.

This question... seems familiar.

It felt like I'd seen it somewhere before, but I couldn't quite place it. Fragments of memory swirled in my mind, yet I couldn't piece together a complete picture.

He didn't dwell on the problem too much, and his attention quickly shifted to the two pages of densely packed solutions that followed.

He adjusted his reading glasses and began to examine the text word by word.

"First, let's use symmetry to simplify the problem by assuming a≥b≥c≥d... Hmm, the idea is very clear."

"The second step is to perform variable substitution and introduce trigonometric functions... This idea is quite interesting."

"The third step, the Lagrange multiplier method... Hmm, I'm quite proficient at it, no problems..."

At first, Liang Tianshi calmly examined the logic and calculations in the derivation process with a scrutinizing gaze. But as he looked, his expression gradually changed, as if he had remembered something.

That initial calm was replaced by a barely perceptible surprise.

The tea on the table had gradually cooled, but he was completely unaware. The only sound in the entire office was the gentle rustling of papers being turned over.

Half an hour later, Liang Tianshi finally saw the last two pages.

He let out a long breath, leaned back in the wide chair, and his expression changed from initial scrutiny to excitement, appreciation, and solemnity.

He pressed the internal phone again and said in a deep voice into the receiver, "Xiao Cai, contact Director Feng Yunhai of the Beijing International Mathematical Research Center for me. Tell him I have something urgent to discuss with him and need him to come over right now. And do me one more thing..."

……

An hour later, there was a knock on the half-open, heavy wooden door of the office, and a refined-looking man walked in with a smile.

The man didn't look young. His hair was neatly combed, and although there were fine wrinkles around his eyes, he was very well-maintained. His well-fitting light-colored shirt further accentuated his extraordinary demeanor.

"Teacher Liang!" The man stepped forward quickly as soon as he entered the room, his tone full of the warmth and respect of a junior meeting an elder. "Why didn't you give us a heads-up before coming to the capital? Otherwise, my fellow students and I could have hosted a welcome dinner for you."

Upon seeing the person who arrived, Liang Tianshi smiled genuinely and waved his hand, saying, "Oh, there's no need for such trouble. As an old man who has retired from the front lines, I feel uncomfortable being surrounded by people wherever I go."

He stood up, pointed to the sofa opposite him, gesturing for the other person to sit down, and continued to joke, "It's such a hot day, yet you made a special trip from Yanbei University to Huaqing Garden. You must be very kind of the head director."

The man was Feng Yunhai, the director of the Beijing International Mathematical Research Center and a professor at the School of Mathematical Sciences of Yanbei University.

He knew his teacher was joking, so he just smiled and sat down on the sofa.

Liang Tianshi carefully examined the man in front of him for a few seconds, his gaze softening, and his tone becoming more friendly and amiable: "Yunhai, you've grown white hair too."

Feng Yunhai was taken aback for a moment, then chuckled and touched his temple: "That's right, Professor Liang. I'll be fifty-seven after my birthday this year. Time really flies. Thinking back, it feels like just yesterday that I listened to your lectures when I was a doctoral student."

"Yes," Liang Tianshi said with a sigh, "it's been almost thirty years in the blink of an eye."

A look of reminiscence crossed Feng Yunhai's face: "So many years have passed, but when I occasionally think back to the days when I studied under you, I still feel very happy."

"I also feel that the most fulfilling thing in my life is teaching you students who can shoulder the heavy responsibility for the country," Liang Tianshi said with satisfaction.

After a brief reminiscing, Feng Yunhai seemed to remember something and casually asked, "Why haven't I seen Xiaodong? Aren't you the one who dotes on him the most? You didn't even let him accompany you to the capital?"

Mentioning his grandson, Liang Tianshi's face showed a helpless yet doting smile: "It's summer vacation now, high school kids, it's rare for them to relax. I came to the capital this time on important business, so I won't let him come along and cause trouble."

Feng Yunhai nodded and said with concern, "Speaking of which, when I called to greet my teacher's wife during the New Year, she was still talking to me about how much effort Liang Qing and his wife had put into Xiaodong's studies. Judging by the time, he should be a senior in high school this year, right? Would he be willing to come to the capital? Perhaps I should discuss it with a few of my fellow disciples and see if it's possible..."

"No need," Liang Tianshi interrupted him, shaking his head, but his tone was calm. "I know this child best. He's not a bad person, but he's definitely not cut out for studying. You and I have both been in academia for so many years, and we both understand that studying requires talent. There's no need to force it; it would only be a waste of the country's resources."

He paused, his tone softening with the gentleness of an elder: "All I hope for now is that this child grows up healthy and doesn't go astray. That's enough. Our family isn't exactly wealthy, but we can certainly ensure he'll have enough to eat and drink for the rest of his life."

Knowing his teacher's upright character, Feng Yunhai nodded and said no more.

After exchanging a few more pleasantries, he finally got to the point: "Teacher, why did you call me here so urgently today? Is there something you need?"

"Hmm," Liang Tianshi's smile faded slightly, and his expression became serious again. He pointed to the three A4 sheets of paper on the coffee table, "Take a look at this."

Feng Yunhai picked up the papers, his gaze falling on the title on the first page. After just one glance, a look of obvious surprise appeared on his face.

"Huh? Isn't this the question you used to test Wei Beichen when you were in the IMO national training team?" He looked up, a hint of reminiscence in his eyes. "I remember it very clearly. Back then, it was because he solved it in less than an hour that you overruled everyone's objections and made the decision to let him, a high school student, represent the country in the IMO."

Liang Tianshi nodded approvingly, a look of reminiscence on his face: "Yes. When I first met Xiao Wei, I only thought he was focused and talented. I never imagined he would soar to such heights, winning gold medals in the IMO for two consecutive years, with perfect scores! Those two years were truly a great source of pride for the country!"

At this point, Liang Tianshi casually asked, "How is that child now? The last time I saw him was about seven or eight years ago, wasn't it?"

Feng Yunhai replied, "Yes, the last time you saw him, he was doing his postdoctoral research with me. Now, he's an assistant professor."

Liang Tianshi: "Are you still studying that Navier-Stokes equation?"

Feng Yunhai: "Yes, I plunged into it and never came out. In the past few years, I have achieved some very significant results."

"The Seven Millennium Problems..." Liang Tianshi sighed. "In this day and age, there are very few promising talents willing to calm down and wholeheartedly engage in this kind of pure theoretical research."

"There are fewer and fewer of them," Feng Yunhai sighed, echoing the sentiment. "Nowadays, talented kids are more willing to make money. After graduation, they go into quantitative investment or work on the hottest field, artificial intelligence."

"That's only human nature." Liang Tianshi nodded and didn't continue the topic.

Feng Yunhai steered the conversation back on track: "So, teacher, you called me here today to ask about Wei Beichen's situation?"

"No." Liang Tianshi shook his head and gestured with his chin to the other two pages in his hand. "Take a look at that."

Feng Yunhai lowered his head as instructed and examined it carefully.

He watched with extreme concentration, nodding occasionally and frowning sometimes. Halfway through, he even looked up and borrowed paper and pen from Liang Tianshi, referring to the process on the paper while rapidly calculating something on a draft paper.

The office fell silent again.

After about ten minutes, Feng Yunhai finally put down his pen, looked up, and had a hint of appreciation on his face.

"The proof process is flawless and extremely rigorous. The core idea he used is the same as that Wei Beichen used back then, and he even optimized the details. Who came up with this?"

Liang Tianshi calmly uttered a few words: "A sophomore at Yannan University."

"Yannan University?" Feng Yunhai frowned. "To solve problems of this difficulty, one must have been on the IMO national team, right? Yannan's mathematics department is very good, but as far as I can remember, there haven't been any Yannan students on the IMO teams in the last two years."

"I haven't paid much attention to competitions in recent years, so there's no need to worry about these trivial details." Liang Tianshi waved his hand, looking intently at him, and posed a crucial question, "Do you know how long it took this child to solve this problem?"

Feng Yunhai shook his head subconsciously.

Liang Tianshi slowly raised two fingers.

"Twenty minutes."

The moment the words left his mouth, Feng Yunhai's expression froze for a moment, and then the composure and calmness that belonged to a top scholar vanished without a trace!

He jumped up from the sofa, his movement so sudden that he knocked over an empty teacup on the coffee table.

"impossible!"

Realizing his lapse in composure, Feng Yunhai quickly straightened the empty teacup he had knocked over and looked at Liang Tianshi with a hint of apology.

"I'm sorry, Professor Liang," he explained with a wry smile, "I'm not questioning what you said, it's just that this is a bit too..."

Liang Tianshi didn't mind at all. He gestured for him to sit down again and said calmly, "Sit down and talk, sit down and talk. I understand your reaction. However, the possibility of this being fake is not very high."

He briefly recounted how his grandson Liang Xiaodong found this mysterious seller through salted fish, and how he sought help from the seller again for a homework question in Han Sibo's "Strong Foundation Program" training class.

"That's the gist of it," Liang Tianshi summarized. "From the time Xiaodong placed the order and made the payment to the time the other party sent over these two pages of complete solutions, no more than twenty minutes had passed. Xiaodong and this person should have had no conflict of interest, and there was no motive for Xiaodong to help the other party falsify the solution."

After listening, Feng Yunhai sat back down on the sofa, his brows furrowed, lost in thought.

He was well aware of the significance of this question.

It is not only difficult, but also requires a clever and ingenious approach, demanding a high level of mathematical intuition and tool application skills from the solver.

Back then, Wei Beichen's ability to solve the problem within an hour had already shocked the entire training team's coaching staff.

Twenty minutes? That's not just genius, that's monstrous.

After a moment's thought, Feng Yunhai offered the most logical guess: "Is it possible that this student has seen this problem before, or a similar solution, somewhere?"

"I've considered that possibility too." Liang Tianshi nodded, clearly having thought of it long ago. "I had Xiao Cai do a quick online search, and I also used some of the best AI models currently available to ask, but the results were all the same. I could find a few people asking this question or having some discussions, but no one had the correct approach, let alone the complete steps."

Feng Yunhai frowned even more deeply. If it wasn't through public channels, then there was only one possibility left.

"Is it possible that when you were in charge of the IMO national team, other coaches collected this problem privately and it circulated within a small circle of competition instructors? This student may not have participated in the IMO, but he may have attended some high-level competition training courses and happened to hear a teacher explain this problem?"

"We can't rule out that possibility," Liang Tianshi admitted frankly.

After all, many years have passed, and the whereabouts of much of the information are now unverifiable. If someone simply memorized the answers, the value of their "genius" status would be greatly diminished.

However, he changed his tone and became serious and solemn again: "But, Yunhai, we should pay more attention to another situation—that is, there really is someone who can solve this problem independently within twenty minutes."

Feng Yunhai's heart skipped a beat again, seemingly out of control.

He still found it hard to believe and couldn't help but raise one last question: "Professor Liang, if a student really has such talent, why is he so unknown? Even without participating in competitions, with this level of ability, wouldn't it be a piece of cake for him to participate in the Strong Foundation Program selection at Yanbei or Huaqing Universities? How could he have just obediently gone to Yannan University through the National College Entrance Examination?"

"That's the crux of the problem," Liang Tianshi sighed. "We have far too little information right now."

He looked at his prized student, a glint of shrewdness flashing in his eyes, and revealed his true purpose.

"I asked President Chang Kai of Yannan University to find out about the female student named Shen Yan, who led a team to participate in this Advanced Mathematics Cup Modeling Competition, and they have already entered the final offline exchange stage."

He paused, then said, word by word, "On July 14th, at Tsinghua University, there will be the final awards ceremony and academic exchange. I plan to test this young man on-site then."

"A live test?" Feng Yunhai's eyes lit up instantly, and he said excitedly, "Teacher, count me in! I have to join in this excitement!"

Liang Tianshi laughed heartily; he knew that Feng Yunhai would react this way, given his personality.

He looked at Feng Yunhai and asked jokingly, "If she's really a promising student, how about we make an exception and transfer her to the mathematics department in Yanbei?"

Feng Yunhai slapped his thigh and answered without hesitation, "Of course, no problem! As long as she's willing to come, I'll personally talk to the admissions office! However..."

He changed the subject, smiling and shaking his head. "I've heard of President Chang Kai of Yannan University; he's a shrewd man. If he really has such a promising talent, he probably wouldn't let him go so easily, would he?"

"It's all up to human effort," Liang Tianshi said, his eyes revealing an unwavering determination.

"I have my own ways of talking to Chang Kai. The key now is to confirm whether this child is indeed a diamond in the rough."

His gaze drifted out of the office.

"If she truly possesses that level of mathematical talent, then unless she is absolutely determined to stay in Yannan, I will definitely strive to ensure that such a genius receives the best possible training."