“Absolutely.”?
?Chapter 39
Vaughn found Ivy’sway of speaking, what he was mentally starting to refer to as herprofessor mode, captivating.
And attractive.Veryattractive.
Fuck you, Darnell, for putting these thoughts in my head.
“The game itself is simple. Two players, two buttons each: red and green. You can’t see what your opponent has chosen until both have selected a color. The point system varies, but the most accepted one is as follows.” Ivy scribbled on the paper, but Vaughn’s eyes were locked on her face. She pushed her tongue lightly into the inside of her cheek as she worked the pen. “If both players select green, they both get three points. If one chooses red and the other green, red gets five points, green zero. If they both choose red, they both get one point.”
Ivy spun the paper around, and Vaughn was forced to look at it.
Player 1: G, R, R, G, G, G, R, G, R, G.
Player 2: R, R, G, G, G, R, G, R, G, R.
Player 1: 17
Player 2: 23
“So player two wins? Just like at the scene?”
Ivy frowned.
“Thesearethe colors from the board.”
“Really? You remembered them all?”
“I have a thing for numbers. They just kinda stick.”
Vaughn made a face. He was about to comment that these were colors, not numbers, undoubtedly making a fool of himself, but Ivy saved him the embarrassment.
“I just converted G to 0 and R to 1—simple binary. Easier for me to remember that way.”
“Ah.”
Still impressive. Vaughn had stared at the digital boards for as long as Ivy had and would have been hard-pressed to remember a single three-color sequence correctly.
Their minds were wired differently, it seemed.
He focused on victims and victimology, Ivy on math and numbers.
“I still don’t understand these math games. Random...” He stopped himself again, recalling Ivy’s lecture on the 100 prisoners problem. “Wait, you’re about to tell me that this game isn’t random, either?”
Ivy laughed. She had a pretty laugh. High-pitched, but also somehow soft. Not shrill.
“There is a strategy to it. A mathematician named Robert Axelrod held a tournament, a computer tournament, in the 1980s. He wanted to know the optimal strategy to win the game. People from all over the world submitted their strategies in the form of simple computer programs. Then he pitted them against each other and tallied their total scores. One strategy came out on top: the tit-for-tat strategy. Essentially, you start out green and only switch to red when, in the previous round, the opponent chose red. If they chose green again, then the tit-for-tat strategist picks green.”
Vaughn drank more of his beer.
“I get it.”
I think.
“Axelrod ran the tournament several more times, with different strategies that mathematicians submitted, and barring a few exceptions, tit-for-tat came out on top. So, intrigued by this, he dug a little deeper. Realized that this strategy could be described simply as starting out ‘nice’ but becoming ‘mean’ if the opponent is ‘mean.’ The key is, though, to be ‘forgiving.’ If the opponent goes back to being ‘nice,’ then you go ‘nice,’ too. I’m not positive, but I’m pretty sure that more papers have been published about the prisoner’s dilemma than any other math problem in history.”
“Really?” They’d both finished their beers and ordered another round. Ivy went for Guinness this time. “All this for a simple math game?”
