Old Carter put down the pencil he was using for calculations and asked, “Did Henry Clark come up with this?”

“……”

Old Carter sighed, “So why are you going on blind dates when there’s such an outstanding boy you’re not even chasing after?”

David Carter: “I like Fassbender too, but can I catch him?”

Old Carter: “Who’s that?”

David Carter: “Magneto.”

Old Carter: “What a coincidence, I like him too.”

“……”

“So, if you solve this problem, Henry Clark will agree to be your boyfriend?”

“Can you not be so obsessed with romance? This is just the entry question for joining the modeling competition team.”

“I’m afraid not.” Old Carter sounded very certain.

“I don’t get it.”

“This is just a stone thrown to test the waters.” Old Carter took off his reading glasses, his gaze deep. “It’s not about the modeling competition at all, it’s about the P/NP problem.”

David Carter looked at the problem again and finally understood where that vague sense of familiarity came from.

The P/NP problem—one of the Millennium Prize Problems, a million-dollar reward, on par with the Riemann Hypothesis and the Poincaré Conjecture.

Henry Clark really is...

“Ambitious.” Old Carter concluded, clearly pleased. “Let me correct myself, this probably isn’t even a problem Henry Clark came up with. It’s the advisor’s idea. The professor at your school who researches Hamiltonian cycles—isn’t that Henry Clark’s advisor? Is his surname Shen or Zeng?”

David Carter was speechless: “You know way too much.”

“Not really, not really. I also know that, although this problem is still extremely far from truly solving P vs NP, solving it could rewrite the course of human history. Anyone with the courage to try deserves respect.”

“Yeah, that’s true.” David Carter thought, Courage, how enviable.

“So, do you want to apply for graduate school in your university’s math department?” Old Carter suddenly changed the subject.

David Carter stared at him blankly, not understanding how the topic had shifted to this.

“If you can prove P=NP, you’ll greatly increase computer processing speed. The time to conquer countless diseases, even Alzheimer’s, will be drastically shortened...” Old Carter continued, “So you’re not considering switching majors for your dad?”

David Carter pointed at herself, then at the problem on the table: “Boss, I can’t even understand this, okay? I’m four years of specialized study away from being able to take the math grad school exam!”

Old Carter laughed, his tone earnest: “You think you can’t catch up to Henry Clark, but is the distance between you and him really greater than the distance between him and the P/NP problem?”

There was simply no way to argue with that.

David Carter spun around and headed for her bedroom door.

Old Carter was still laughing, his deep, raspy chuckle echoing behind her.

“Miss David Carter, in this long and beautiful life, if you truly find something you want to do, then no matter when you decide to start again, it’s never too late.”

Author’s note:

Here’s a supplementary excerpt:

P refers to problems that computers can solve quickly; NP refers to problems for which we want to find the optimal solution. If P=NP, then we could easily find the solution to any given problem. P=NP would mean a dramatic transformation of the society we know—medicine, science, entertainment, and the automation of all human tasks would immediately undergo a qualitative leap.

[Lance Fortnow, The Boundary of Possible and Impossible: The Curious History of the P/NP Problem]

Chapter 6: Equations

The aroma of crucian carp and tofu soup still lingered in the house. David Carter returned to her room. Late at night, in the quiet, her desk was still covered with study materials for the teacher certification exam.

After falling ill, Old Carter had become almost like a mystic.

Sometimes he would suddenly reminisce about the past, sometimes he’d make chicken soup, and sometimes he’d launch into soul-searching questions. David Carter tried hard not to think about Old Carter’s last few words, but how could she not?

As the daughter of a former mathematician, her math foundation was indeed solid.

When she was little, not only was Old Carter’s approach to her math education extraordinary, she herself was also very interested in math. She was always happy to attend math olympiad classes.

If she had stuck to that path in her youth, she might not have become as brilliant as Henry Clark, but at least she wouldn’t have felt so ignorant and inferior when faced with that problem.

But at some point, she gradually stopped attending classes and stopped reading any math-related books in the library.

She became afraid of math, felt fear and aversion toward it, and firmly believed it was a field for geniuses, unattainable for ordinary people.

Thinking back to that time, David Carter felt a chill all over and quickly forced herself to stop her mind from wandering.

Her life had gone off track long ago, and so be it. Right now, the most important thing was still Comrade Old Carter.

David Carter quickly rubbed her face, turned on her computer, and looked up information about arranging living environments for Alzheimer’s patients, trying to find something to do that wouldn’t let her mind wander.

Alzheimer’s manifests as short-term memory loss, but long-term memories can be recalled.

So, you can place items that make them feel comfortable and happy in prominent places at home, such as nostalgic photos, favorite plants...

And since Alzheimer’s patients often can’t tell which door is their own, you can put special marks on the door to help them distinguish it.