Chapter 63 - 48: Feng Yunhai
Not long after Liang Tianshi hung up, his phone went DING. He had received several pictures from his grandson, Liang Xiaodong.
He put on his reading glasses and leaned closer to his phone screen.
The images were clear, but the dense script and mathematical symbols were still a bit strenuous for someone his age to read on a small phone screen. He clumsily swiped and pinched to zoom on the screen, his brow furrowed slightly.
"This is too tiring for my eyes," he muttered to himself, then pressed the button for the intercom on his desk.
"Cai, come in for a moment."
The door was pushed open gently, and a sharp, capable young secretary walked in.
"Elder Liang."
"Yes," Liang Tianshi said, pointing to his phone. "I received some pictures on WeChat. Help me print them out, enlarged. A4 paper is fine."
"Of course, Elder Liang." Cai answered crisply and stepped forward, skillfully operating the phone.
A moment later, accompanied by the faint hum of the printer, three sheets of A4 paper, still slightly warm, were placed on Liang Tianshi’s desk.
Cai straightened them, handed them respectfully to Liang Tianshi, then slipped out of the room soundlessly, thoughtfully closing the office door.
The office fell silent once more, with only the quiet hum of the central air conditioner pushing out cool air.
Liang Tianshi spread the printouts on his desk, his gaze first falling on the top of the first page.
[Given non-negative numbers a, b, c, and d that 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 gaze sharpened.
’This problem... it seems a little familiar.’
He felt as if he had seen it somewhere before, but he couldn’t quite recall the specific source. Fragments of memory tumbled through his mind, but they refused to form a complete picture.
He didn’t dwell on it for too long, his attention quickly shifting to the two pages of dense, detailed proofs that followed.
He adjusted his reading glasses and began to review the solution, line by line.
’First step, use symmetry. We can assume a≥b≥c≥d to simplify the problem... hmm, the approach is very clear.’
’Second step, variable substitution, introducing trigonometric functions... this idea is interesting.’
’Third step, the Lagrange multiplier method... hmm, applied skillfully, no issues here...’
At first, Liang Tianshi calmly examined the logic and calculations of the derivation with a critical eye. But as he continued to read, his expression gradually changed, as if he had just remembered something.
His initial composure was replaced by a hint of almost imperceptible surprise.
The tea on his desk had grown cold, but he was completely oblivious. The only sound in the entire office was the soft rustle of paper being turned.
Half an hour later, Liang Tianshi finally reached the end of the two pages.
He let out a long breath and leaned back in his large chair. The look on his face had transformed from its initial scrutiny to one of excitement, admiration, and gravity.
He pressed the intercom button again and spoke into the receiver in a low, serious voice, "Cai, contact Director Feng Yunhai at the Imperial Capital International Mathematics Research Center for me. Tell him I need to see him about something urgent, and that he should come here right away. And one more thing..."
「...」
An hour later, two knocks—KNOCK KNOCK—sounded on the heavy, half-open solid wood door. A refined, scholarly man then walked in with a smile.
The man was no longer young, his hair meticulously combed. Although fine wrinkles had appeared at the corners of his eyes, he was remarkably well-preserved. A well-fitting, light-colored shirt further accentuated his distinguished aura.
"Liang!" The man strode forward as soon as he entered, his voice filled with the warmth and respect a junior shows to an elder. "You came to the Imperial Capital! Why didn’t you give us a heads-up? Otherwise, I and a few of our fellow students could have arranged a proper welcome for you."
Seeing his visitor, a genuine smile spread across Liang Tianshi’s face. He waved his hand dismissively. "Ah, no need for all that trouble. I’m just an old man who’s retired from the front lines. Being fussed over everywhere I go just makes me uncomfortable."
He stood up, gestured to the sofa opposite him, motioning for the other man to sit. He continued to tease, "Though on a day this hot, making a great director like you run all the way from Yanbei University to Huaqing Garden... I’ve really put you to work."
The man was indeed Feng Yunhai, the director of the Imperial Capital International Mathematics Research Center and a professor at Yanbei University’s School of Mathematical Sciences.
He knew his former teacher was joking, so he just smiled and took a seat on the sofa.
Liang Tianshi studied the man before him for a few seconds, his gaze softening. His tone became warmer and kinder. "Yunhai, you have white hairs now too."
Feng Yunhai was taken aback for a moment, then touched his temples with a self-deprecating smile. "Isn’t that the truth, Liang. I’ll be fifty-seven after my birthday this year. Time flies, doesn’t it? Thinking back, the days when I attended your lectures as a doctoral student still feel like yesterday."
"Yes," Liang Tianshi said, also feeling a wave of nostalgia. "In the blink of an eye, it’s been almost thirty years, hasn’t it?"
A nostalgic expression appeared on Feng Yunhai’s face. "All these years have passed, but when I occasionally recall the days I spent studying under you, I still remember them as a very happy time."
"I feel the same. The most fulfilling thing in my life has been teaching students like you, who have gone on to become pillars of our country," Liang Tianshi said with satisfaction.
After their brief trip down memory lane, Feng Yunhai seemed to recall something and asked casually, "I don’t see that boy, Xiaodong. Aren’t you the one who dotes on him the most? You came to the Imperial Capital and didn’t have him accompany you?"