Seedwick

When the lab tests a solitaire rule, nobody shuffles the cards by hand. The computer does it. But a computer cannot truly shuffle at random the way a pair of hands can. What it does instead is start from a number, called a seed, and then follow a long and complicated recipe that stirs the cards into an order that looks completely random. The clever part is that the recipe never changes. Start from the same seed, follow the same recipe, and you get exactly the same shuffle, every card in exactly the same position, every single time. The mixing looks wild, but it is perfectly repeatable, like a magician's trick that works the same way on every performance.

Seedwick learned just how much that mattered on the day a young weasel named Quill refused to believe him.

Seedwick had run a careful test comparing two rules and found that one of them won a few more deals than the other. He was quietly pleased with it. But Quill, who had been reading over his shoulder, folded his arms tight across his chest.

"I don't believe you," Quill said. "Maybe you got lucky deals. Maybe you made a mistake somewhere. Maybe you just wanted your rule to win, so you saw what you wanted."

A few animals nearby drew in a sharp breath. It was a prickly thing to say out loud. Seedwick's whiskers trembled, and warmth rushed into his cheeks. It never feels good to be doubted, especially about work you did carefully. For a moment he wanted very badly to argue, to list every careful step, to insist.

Instead, he took one slow breath. Then he did something far more powerful than arguing. He tore a small corner off his notes, wrote a single number on it, and held it out.

"This is my seed," he said. "Type it into the lab. It will build exactly the same deals I used, in exactly the same order. Then run the two rules yourself and see what happens. You don't have to believe me at all. You can check."

Quill hesitated, looking at the slip as if it might bite. Then, a little grudgingly, he took it, sat down at the lab's terminal, and typed the number in. The lab stirred its recipe, and out came the same deals Seedwick had tested, down to the final card. Quill ran both rules. The solver played every game while the two of them watched in silence.

The results came back identical to Seedwick's. The same wins. The same losses. Even the same deals marked not sure yet.

Quill's arms slowly unfolded. "Oh," he said. "You were right." He paused, frowning at the screen. "And I didn't have to trust you to find that out."

"That's the entire point," said Seedwick, and now he was smiling, all his earlier prickliness gone. "A result that nobody else can check is really just a story you're telling. Maybe a true story, but still a story. A result anyone can rebuild from a seed is something people can rely on, even people who don't like me, even people who were sure I was wrong. Scientists call it reproducibility. If your result is real, anyone following your recipe should get it too."

Quill turned the slip of paper over in his paws. "Could I keep this?" he asked, almost shyly. "I want to test a third rule on the very same deals, and see how it compares to yours."