Charlie hadn't retreated into P vs. NP in 25 years. But, then again, his baby girl hadn't gone to college during any of those 25 years. He had held it together while he drove her to the school (Stanford! Why couldn't she just go to CalSci?), and while he and her mother helped her to unpack her things from the car, but as soon as he got home he buried himself in the math, spending five days straight in the garage buried in his equations.

At the end of five days, Don decided it was time for his brother to come back into the real world. Knowing that he probably couldn't get Charlie out of his funk alone, he asked Amita, Larry and Alan to help him. Despite the fact that this had to be the weirdest intervention in history (have you ever heard of people urging a friend to kick the math habit?), Don felt confident that they could pull his brother from his reverie and bring him back to reality by the time Parents' Day came along.

"Charlie?" Don called, leading the two older men into the garage. Charlie stood on the far end of the garage, staring at the blackboards. Don knew what that meant; Charlie was at some sort of standstill, and he was trying to think it through in his head. "Charlie?" Still no response. Don sighed. "Look, Charlie, I know you're upset, but you need to snap out of it. For Maggie's sake—it's going to be parents' day soon, and it really wouldn't be good if you missed it because you were so absorbed in the math that you forgot." Charlie sat down in his chair, stunned.

"Charlie, can you hear me?" Amita asked.

"This isn't supposed to happen," Charlie finally breathed. His friends exchanged looks.

"Of course it's supposed to happen, Charlie," Alan said sympathetically. "Eventually, every baby has to grow up and strike out on her own. Even Maggie. Just like you and Don had to eventually—"

"Not that. That's a biological fact—a horrible fact, but a fact. This, though...this is impossible." Now they were all very confused.

"Charlie, what are you talking about?" Alan demanded.

"I used to bury myself in P vs. NP because I thought I couldn't solve it, so it would never end. I could hide there forever if I needed to," Charlie explained. He looked up at his family hopelessly. "But I was wrong. Now I can't hide there anymore," he finished sulkily. It took a few minutes for what he was saying to sink in.

"Charles...are you saying what I think you're saying?" Larry asked slowly. Charlie nodded. Truly despondent, he moaned his reply.

"Yes, Larry. I've solved P vs. NP."