Photo by Todd Klassy

By day, Avi Rubin is a computer security consultant and a professor of computer science at Johns Hopkins’ Whiting School of Engineering. But by night — and on the weekends, and whenever his wife doesn’t mind too much — Rubin is a poker aficionado, one of those real obsessives with his sights set on the World Series of Poker in Las Vegas. And with a talent for numbers and an obsessive focus on probabilities, he just might end up making it there.

Rubin sees the game in terms of his academic interests — game theory, machine learning, combinatorics. A true computer scientist at heart, he envisioned a poker hand as a finite, countable structure. Once the first cards are dealt (in Texas Hold-Em, each player is dealt two cards face down; five communal cards are dealt faceup), the rest of the game unfolds like a kind of decision tree. Rubin crafted a program to determine the relative probabilities of success given particular variables — his position in the betting, number of opponents, etc. “For any given spot in the decision tree,” he told Johns Hopkins Magazine, “I could come up with a probability distribution of different plays. Then I could write a learning program that I could use as a simulator on the computer and play a thousand times with particular settings, then tweak the settings and run it again to see if I do better, and work backward from it to infer why that was a better play in that situation.”

But because computers can’t yet model the full complexity of playing with real human beings, who bluff/get bored/try to show off/otherwise behave unpredictably, Rubin sat in on weekly games with friends, many of whom were doctors and lawyers. “The lawyers tend to be better,” he says. “The math in poker is basic arithmetic, it’s not that hard. But you still have people, like a lot of the doctors that I play with, who’d rather not bother with all the math. They feel that they have enough intuition for the game.” But that intuitive technique tends to backfire, in Rubin’s experience:  “The fundamental math is much more important. If you’re a solid mathematical player, in the long run you’re going to kill the intuitive player.”

Before poker, it was pool. Rubin, who Dale Keiger describes as “serially all-in,” became obsessed with that game in graduate school. He watched instructional videos, Hollywood pool hustler classics, and routinely stayed up til 2 a.m. playing. When he and his wife, Ann, were looking for a house in Baltimore, he insisted that it have a room big enough to accomadate his prized tournament-sized pool table. While Rubin’s poker craze may require less bulky equipment, that doesn’t make it all that much more fun for Ann. “Poker became an annoyance, really, because it was much more of an obsession than anything else. Part of this obsessiveness is he wants to talk about it,” she says. (Instead, she’s trying to get her husband to take cooking classes, making her own gamble that he’ll get obsessed the way he tends to, and she’ll come home to gourmet meals.)

At a recent tournament at Delaware Park Casino, he finished a (to him) disappointing eighth — but that’s unlikely to set him back. “When Avi sets his mind on something, there’s no stopping him,” Ann told the Magazine. We have no doubt.