After losing the first game of the match to the computer Go player AlphaGo on the previous day — something that the majority of the world’s top players had thought to be practically impossible just months ago — Lee’s play exhibited a sense of calm patience and steadiness, which was not evident the day before.
But somehow it wasn’t enough.
AlphaGo met Lee’s solid, prudent play with a creativity and flexibility that surprised professional commentators, eventually consolidating its advantage in the endgame.
Finally, after a tightly fought contest which left spectators on the edge of their seats, Lee was left with no better move than to resign.
This leaves him trailing 0–2 against AlphaGo in the best of five match.
A completely different game
While yesterday, it could be said that Lee may have underestimated his opponent and played too aggressively in the early stages of the game, today was quite the opposite.
If anything, Lee’s play in the second game was somewhat too cautious, but that is not to say that Lee played badly.
Such play from a Go master of Lee’s caliber would usually strike fear into the hearts of opponents, because it leaves behind few weaknesses and quietly accumulates power, waiting for the opportune moment to strike — that is, when the opponent makes a mistake.
Victory cannot be forced
As Sun Zi explained in The Art of War, “Invulnerability depends on one’s own efforts, whereas victory over the enemy depends on the latter’s negligence.”
“. . . Therefore it is said that victory can be anticipated, but it cannot be forced.”
This seemed to be Lee’s strategy for game two. As it turned out, there were only two problems with this plan:
Firstly, the machine wasn’t at all intimidated by Lee’s quiet confidence.
And, secondly, despite AlphaGo playing some very unusual moves, Lee never seemed to find an opportunity to land a knockout punch.
Brief analysis of game two
The following are An Younggil 8p’s preliminary comments for game two…
An unusual opening
AlphaGo, playing Black today, placed its first move on the star point, and Black 3 was the first 3-4 point opening move we’ve seen from AlphaGo so far.
White met AlphaGo’s opening formation with one start point corner and a 3-4 point corner of his own.
Black 13 was creative, and White 14 should have been at K4.
Black 37 was a rare and intriguing shoulder hit, but Black 43 and 45 were a little heavy.
White’s counter from 46 to 56 was exquisite, and White took the lead.
AlphaGo redresses the balance
White 70 was slack. It should have been in the center around F10, to pressure Black’s group.
Black 73 and 81 were calm and solid plays, and the game became even again.
AlphaGo’s continuation up to 99 was patient and effective, and the game seemed to be slightly better for Black.
However, White 102 to Black 113 was a sophisticated sequence, and the game became even again.
Lee Sedol misses a chance
White 114 was questionable. Entering the corner at R17 would have been bigger.
White 120 to 122 was a sharp combination, but Black’s responses through to 127 were patient once again.
White 144 was a mistake. It should have been at N18 or at O17, in order to make the game more complicated.
AlphaGo closes out the game
Black 151, 157 and 159 were brilliant moves, and the game was practically decided by 165.
However, Black 167 was incomprehensible and White had one last chance. Perhaps AlphaGo believed that it could still win with this move?
White 172 was the losing move. Rather than capturing Black’s top right stones in a snapback, he should have pushed at 173. Black P17 and White M18 can be expected to follow, leading to ko.
Since White missed his chance, the game was over. AlphaGo’s endgame after White 172 was accurate once again and there were no more chances.
Summary of the game
AlphaGo’s style of play in the opening seems creative!
Black 13, 15, 29 and 37 were very unusual moves, but the game was still well balanced up to White 40.
The result from Black 43 to White 56 seemed at first to be disaster for Black, but surprisingly, AlphaGo wasn’t that far behind.
After Black took the lead, Black 139 and 167 appeared to be mistakes, but since Lee didn’t try to punish the moves it’s very difficult to say for sure without playing against AlphaGo.
Lee did his best in the second game, and didn’t try to test the strength of AlphaGo’s opening like he did in game one.
He spent more time in this game, and was in byo-yomi after about 140 moves.
However, Lee’s overall play seemed a little passive in the end. He didn’t play severe moves or seek to complicate the game, even though he was already behind.
It seems that he struggled to count accurately under the time pressure, and he missed a good chance near the end (White 172).
Unlike game one, AlphaGo didn’t make any serious mistakes, and Lee didn’t get any clear chances to win after he gave up his advantage around Black 73.
Post-game press conference
At a post-game press conference, as Lee Sedol and DeepMind CEO Demis Hassabis were bombarded by an epilepsy inducing quantity of flashing cameras, Hassabis described the game as “unbelievably exciting and incredibly tense.”
He expressed Team AlphaGo’s excitement that “AlphaGo played some quite surprising and quite beautiful moves (according to commentators), which was pretty amazing to see.”
Lee Sedol was full of praise for AlphaGo, remarking that, “Yesterday I was surprised, but today, more than that, I’m quite speechless.”
He added, “. . . there was not a moment in time where I felt that I was leading the game.”
Further praise came from the official professional commentators, Yu Changhyeok 9p and Michael Redmond 9p. Both remarked on AlphaGo’s impressive play in the endgame.
When a journalist asked Lee what he thought AlphaGo’s weaknesses were, he quipped “I guess I lost the game because I wasn’t able to find any weaknesses.”
In response to the same question, Hassabis explained that while DeepMind can estimate AlphaGo’s strength internally, “we need somebody of the incredible skill of Lee Sedol to creatively explore and see what weaknesses AlphaGo maybe has, so we can see them.”
“That’s why we’re having this match, to find out,” said Hassabis.
Follow the match
AlphaGo is now leading the match 2–0, which means Lee Sedol needs to win the next three games to defeat it.
Game three of the match will be played on Saturday March 12.
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AlphaGo vs Lee Sedol – Game 2