Something I found particularly notable in the recent
DeepMind AlphaGo vs Ke Jie analysis videos is how critical AlphaGo was of a sequence of 4 moves Ke played in game 1, quickly losing 10% win rate (he'd already lost a little and was black so AG went from about 55% up to 65% which is approaching 70-80% game over level -- it's not really a probability). As throughout the whole video Ke accepted the criticism gracefully (much humbler than a year ago!) and showed a tewari analysis (to 3-3 invasion of 4-4 and double hane) saying that he knew his result sucked. For the best human in the world to be told he keeps making mistakes from bad to worse, rather like when a pro reviews my game, was amusing/sobering.
In summary:
- Ke's high extension on the right side had already come in for some criticism (AlphaGo had preferred a low extension, or invading the top at
a earlier).
- When AlphaGo invaded at

Ke realised his formation was bad: to be better either move high extension to low so there is no slide (AlphaGo would then shoulder hit the extension, they looked at some variations), or move 3-3 to 4-4. He had thought about reinforcing for his previous move (e.g. big knight shimari to lower side) but that was unsatisfactory as white can still easily sabaki on the right side.
-

was bad, -3% said AlphaGo. It liked to just tenuki and invade at the top (seems to me a you-destroy-my-thing so I-destroy-your-thing balance, as more stones added to area it gets smaller, also if black invaded there before right side extension and white pincered then AG liked black to tenuki and extend on right side, already made top smaller in sente).
-

was bad, -2%. It preferred 2 space jump to
b to grow lower side (Ke never considered), after peeping ladder on left exchange. Its thin shape made Ke uncomfortable.
-

was sharp, Ke didn't expect it: even normal answer to the kick was bad for him. Apparently some other humans, maybe Gu Li, had suggested it though.
-

was bad -2%. AlphaGo preferred to just dodge to
c. Fan showed a variation in which AlphaGo ended up capturing the stone on the right ("it got more territory than me in my area!" says Ke), but black squeezed the outside to develop the lower side and got sente to extend on upper right side. Damage limitation.
-

was bad -3%. AlphaGo says hane underneath. The trade of game was good for white.
$$Wc AlphaGo (white) vs Ke Jie, game 1.
$$ +---------------------------------------+
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X . X O . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . a . . . . . . . |
$$ | . . X O . . . . . , . . . O . , O . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . X O X O . . . . . . . . . . . . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . . X . . . . . . . . . . 3 . 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . b . 6 2 . . |
$$ | . . . . . . . . . . . . . . . 5 . . . |
$$ | . . X , . . . . . , . . . . . 9 8 . . |
$$ | . . . . . X . . . . . . . c . 7 X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+
- Click Here To Show Diagram Code
[go]$$Wc AlphaGo (white) vs Ke Jie, game 1.
$$ +---------------------------------------+
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X . X O . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . a . . . . . . . |
$$ | . . X O . . . . . , . . . O . , O . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . X O X O . . . . . . . . . . . . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . . X . . . . . . . . . . 3 . 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . b . 6 2 . . |
$$ | . . . . . . . . . . . . . . . 5 . . . |
$$ | . . X , . . . . . , . . . . . 9 8 . . |
$$ | . . . . . X . . . . . . . c . 7 X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]