xiayun wrote:I think the 3-3 invasion didn't really go well with the first 3-3 move at the upper left. When AlphaGo played the early invasion, it normally has a 4-4 or 4-3 on the other corner. I understand Ke Jie's strategy was to take territory first, but two 3-3s were probably a little extreme.
Actually, I think it is the adjacent corners rather than opposite corner that have more bearing on the merits of the early 3-3 invasion of a bare 4-4 (one with no extensions). If we look at when Master played it, there are strong (or reasonably strong) stones (marked) in those areas, which act to somewhat mitigate the influence of the resulting white wall (not hugely significant, but did Master only 3-3 invade as black?). Michael Redmond pointed this out in his review of the Gu Zihao game below:
$$B Master #36 vs Gu Zihao
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$$ | . . . . . . . . . . O O X X . . . . . |
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$$ | . . . , . . . O O X X . . O . X . . . |
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- Click Here To Show Diagram Code
[go]$$B Master #36 vs Gu Zihao
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$$ | . . . . . . . . . . O O X X . . . . . |
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$$ +---------------------------------------+[/go]
In this game the top left approach stone was played before the 3-3 and isn't exactly strong, but Master uses its sente after the 3-3 to then settle it with attach at
a. The approach timing before the 3-3 can be seen as a probe: if played after the 3-3 white is likely to kick to attack more strongly.
$$B Master #32 vs Kim Junh-hyun(?)
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$$ | . . a O . . . . . , X . . X . X . O . |
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$$ | . . . O . . . . . , . . . # . , X . . |
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$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go]$$B Master #32 vs Kim Junh-hyun(?)
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$$ | . . . O . . . . . , . . . # . , X . . |
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$$ +---------------------------------------+[/go]
But Ke Jie's 3-3 invasion doesn't share these properties: he has a strong shimari in the upper right but it's rather far away and pointing the wrong direction (would be better at
a), and the lower left there is no black presence but a white high big shimari which which works better with the resulting wall, and also makes a wedge have less space to invade.
[go]$$B Ke Jie vs AlphaGo game 1
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$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go][go]$$B Ke Jie vs AlphaGo game 1
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$$ | . . X . . . . . . . . . . X . a . . . |
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$$ +---------------------------------------+[/go]
Surely Ke Jie will have studied these positions deeply, so I do find his 3-3 surprising. Maybe he just wanted to look cool and give a nice story, or wanted AlphaGo to teach him how to deal with an early 3-3 (based on this 1 game the answer could be one-point jump rather than hane), but 'wasting' such a big match to do so (rather than one of the Master games) is odd.