Korean Go champion Lee Se-dol lost to artificial intelligence AlphaGo again Thursday in the second round of the five-game Go match in Seoul, portending a grim outlook for the human player in the remaining three games.
AlphaGo, which played black, placed the first stone on the 4-4 point in the upper right-hand side, an intersection of the fourth line from right and fourth line from top, a conventional opening in Go.
In the initial phase of the game, AlphaGo built a fortification in the upper territory of the board by placing two more stones -- one in the left top and another in the upper middle. It tried to scatter its stones across the board later.
|Go player Lee Se-dol (right) makes his first move against Google’s AlphaGo during the second round of Google DeepMind Challenge Match in Seoul on Thursday. (Google Korea)|
After suffering an unexpected defeat a day before, Lee seemed to be more cautious, with a standard opening strategy, placing his first stone on the 4-4 point in the bottom left side.
Lee tried to expand the white presence in the lower territory in the beginning.
The game moved slower than the first match as the human champion used more time than he did the previous day.
“In an important game like this, players usually spend more time,” said Michael Redmond, the only Western highest-ranking ninth dan Go player and one of the commentators of the match.
“It is a much more conservative game.”
About 50 minutes into the match, AlphaGo made a highly unusual move, by placing a stone on the 5-10 point, the intersection of the fifth line from right and the 10th line from top.
It did not appear to be aimed at attacking or fending off any attack by the human opponent, since there was just one white stone placed nearby, on the 4-9 point.
The move made human champion Lee leave his seat to take a break, or likely to pull himself together after the unconventional move.
“It was a creative move, which I don’t see in professional players’ games,” said Redmond.
Around 1 hour and 50 minutes into the match, black ramped up its efforts to fortify its grip on the upper territory of the Go board with a 19-by-19 grid.
Black formed a linear formation horizontally across the top part of the board, which made it tough for Lee to invade.
The linear top formation nearly eliminated Lee’s chance to capture territory above the fourth line on top.
When the two players went into 2 hour and 30 minutes, white tried to dive into the top middle area for some profits despite a slim chance. Black, however, waged a sort of counterattack by placing a stone in the relatively vacant -- at the time -- middle territory of the board, which led to a fight in the center of the board.
Although white received a 7.5-point advantage for playing second, black took a slight lead throughout the game.
Around three hours into the game Lee, who had a fortified single-point eye, a single open point surrounded orthogonally by four white stones, made bold moves in the center of the board, seemingly insinuating, according to Redmond, that “I am not weak, black is weak.”
Lee was able to keep his cool during the game, but used up three one-minute time slots,
According to Chinese Go rules adopted in the match, the opponents should make a move within a minute. Three violations lead to a loss.
The fierce tug of war continued for 4 1/2 hours with black keeping the lead with more than 10 points ahead of its human opponent.
“2016 will be a historic year for both the Go and AI communities,” Chris Garlock, a cocommentator of the event said.
Echoing him, Redmond also said that “AI made a huge step forward.”
In Game 1 on Wednesday, the human Go grandmaster, with 18 international titles under his belt, underestimated his opponent when he faced off with the computer software.
“I was really surprised. I never imagined I would lose,” said the Korean Go player after the first showdown, adding, “I really want to deliver respect to the team of developers behind AlphaGo.”
The stunning win by the program made headlines around the world.
Around 80,000 people worldwide watched the second round of the five-game match via the official YouTube channel for the showdown, compared to 90,000 viewers for the Wednesday game.