Chapter 39
Vaughn found Ivy’s way of speaking, what he was mentally starting to refer to as her professor mode, captivating.
And attractive. Very attractive.
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.
“These are the 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?”
“That’s the thing. Axelrod realized that it was more than just a game.
It was an allegory for life. Biology follows this pattern; ecosystems, too.
A species needs a level of cooperation with other species for the betterment of both.
And within species, packs, families, everything—this tit-for-tat strategy wins out.
You can’t be a complete pushover. If someone does something bad to you, then you need to hit back.
But you also need to be forgiving. The ‘tit-for-tat’ or ‘nice guy’ strategy has been applied to everything from war, business, and trade to cybersecurity. ”
“Interesting.” Vaughn wasn’t just paying lip service. He had no idea about the widespread application of such a simple game. To him, math was reserved for calculating sales taxes and interest rates. “I just don’t understand why someone is using these games to kill people.”
Ivy’s face dropped.
“That I can’t help you with,” she said solemnly. She took several large gulps of her Guinness. “What I don’t understand is why someone would go to an abandoned barn in the middle of nowhere to play.”
“That’s the easy part. We found an ad on Aaron Treadman’s computer, in his email. It advertised a game show for a streaming service, offered a payout of 1 Bitcoin to the winner.”
“So it’s about the money?”
“It’s always about the money.”
Their eyes met again, and Vaughn immediately dropped his gaze. He noticed Ivy’s glass.
“Look at that. You split the G.”
“Of course. The volume of the glass is sixteen ounces. The glass itself is tulip-shaped, and the middle of the G is roughly 3.75 inches from the rim. Applying a volume-height curve, that makes the volume of beer to be removed roughly seven ounces. A typical mouthful of beer is three ounces, so I calculated the number of mouthfuls to be two plus an additional third.”
Vaughn craned his neck forward. His eyes widened.
“You . . . you calculated all that in . . . seconds? The . . . volume . . . the—”
Ivy broke into laughter. “No, I just guessed.”
Vaughn laughed, too.
After they were finished, he drove her back to the assisted living home to retrieve her car. He no longer saw flashing police cherries in the distance. Instead, the entire field had been lit up with massive floodlights. It looked like an evening baseball field, ready for the opening pitch.
“Thank you for your help tonight, Ivy.”
He saw lines around her eyes and reached out with his thumb. She pulled back at first, then let him touch her. He gently rubbed her skin.
“Just marks from the mask.”
Ivy leaned forward. Vaughn did the same.
Their lips almost met.
“Thank you,” Ivy said, stepping back.
Vaughn nodded.
As much as he’d enjoyed and needed the reprieve, it was time to get back to work.