People didn’t think this would happen for at least 10 years; it’s a sign of how far artificial intelligence has come.
For the first time in history, a computer has beaten the human world champion at Go.
Go is an ancient Chinese game in which you place stones on a 19 by 19 board, and capture your opponent's stones by surrounding them. The rules are very simple, but they give rise to a complex, subtle game.
This morning, AlphaGo, a computer designed by the Google-owned, London-based company DeepMind, defeated Lee Sedol, the reigning Go world champion, in the fifth game of a five-game series. AlphaGo beat Lee 4-1 overall, with Lee taking the fourth game, when the series was already lost.
AlphaGo / YouTube / Via youtube.com
Here's why that's a big deal. First, Go is incredibly complicated – millions upon millions of times more complex than chess.
"It's sheer mathematics," Professor Murray Shanahan, an AI researcher at Imperial College London, told BuzzFeed News. "The number of possible board configurations in chess, of course, is huge. But with Go, it's enormously larger."
In chess, there are on average about 35 to 38 moves you can make at any point. That's called the "branching factor". In Go, the branching factor is about 250. In two moves, there would be 250 times 250 possible moves, or 62,500. Three moves would be 250 times 250 times 250, or 15,625,000. Games of Go often last for hundreds of moves.
It's sometimes said that in chess there are more possible games than there are atoms in the observable universe. In Go, by one estimate, there are something like a trillion trillion trillion trillion trillion trillion trillion more than that. To write the total number out, you'd need to put a 1 followed by 170 zeroes. That's why, nearly 20 years after computers became better at chess than humans, they've only just caught up at Go.
That's called "brute force" processing. "You simply can't use brute force for Go," says Shanahan. "You can't with chess either, but you can tackle it that way a bit, use brute force to search ahead through many, many possibilities. But with Go the number of possible board combinations is enormously larger."
The branching factor means that even a few turns ahead, the number of possibilities becomes too huge for even the fastest computer to search through.
That means that AlphaGo's victory isn't simply a product of computers getting faster and more powerful. Computers will never be powerful enough to brute-force Go. Software is always more important than hardware.
"The general rule of thumb in these areas is that hardware counts for an enormous amount, but software counts for more," Eliezer Yudkowsky, an AI researcher and co-founder of the Machine Intelligence Research Institute (MIRI) in California, tells BuzzFeed News. "If you have a choice between using software from 2016 and hardware from 1996, or vice versa, and you want to play computer chess or Go, choose the software every time."
Human players don't follow every possible branch that the game could go. They look at the board and see patterns. "The way that human players play chess or Go or any game like that," says Shanahan, "is that we get to recognise what a good board pattern looks like. There's an intuitive feel for what's a good strong position versus what's a weak one.
"Human players build that up through experience. What DeepMind have managed to do is capture that process using so-called deep learning, so it can learn what constitutes a good board configuration."
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