Some highlights from game 2. Text refers to the diagram above the text (I wish I could adjust the spacing to make this clearer).
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[go]$$Wc Move 18, white to play
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . O . . . . . . . |
$$ | . . . X . . . . . . . . . X . c X . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . W W . . a . . . . . . . . . . . . |
$$ | . . . . . . b . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . X . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
As black, I get nervous in this type of position: I remember my teacher saying "you just kick to make white heavy, then attack", but the attack always seems to fizzle out. Those two stones are surprisingly resilient! (See discussion of
Kirby's recent game: slightly different context, but similar idea.) LZ-258 has trouble choosing between
a through
c for white's next move. The game move (not KataGo's choice as the self-play for this game starts from move 26) is not on LZ's radar, but gets rated as equally good when I show it to LZ, even though to me it looks slightly outrageous. Try to guess what the game move is, then check the SGf below :-)
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[go]$$Wc Position after black 57
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ | . . O . X X X . X . . O . . O O X . . |
$$ | . . . X O O . . . . . a X X O X X . . |
$$ | . X X X X . . . . . . . . O X X . . . |
$$ | . . O O O X X O . . . . O . O X . . . |
$$ | . . . . . O O . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . . X . O . . O . . . . . . . X . . . |
$$ | . . . X X X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . B . . X . X X . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . O . . . . . . . b . . O . . . |
$$ | . . . c . . . . O . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
For me, the above position is the most interesting moment of the game. Black has just played the marked stone -- LZ's third choice (after
a and
b, and very slightly ahead of
c). I think of this sort of thing as a "beginnner's moyo" move: pure gote to "surround 40 points of territory", completely unaware of how easy it is to reduce/invade that territory -- and this tactic works well against other beginners who also don't know how to handle the moyo. Of course KataGo has looked more deeply into the position, understands that the "territory" isn't real, but chooses to play this move anyway. Take a moment to try and imagine how the board might look, say, at move 120, then have a look at what actually happened.
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[go]$$Bc Black to respond to move 66
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ | . . O . X X X . X . . O . . O O X . . |
$$ | . . . X O O . . . . . . X X O X X . . |
$$ | . X X X X . . . . . . . . O X X . . . |
$$ | . . O O O X X O . . . . O . O X . . . |
$$ | . . . . . O O . . . . . . . . . . . . |
$$ | . X O X . . . . . . . . . . . . . . . |
$$ | . . X . O . . O . . . . . . . X . . . |
$$ | . . . X X X . . . . . . . . . . . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . O . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . X . a X . X X . |
$$ | . . . . . . . . . . . . . W . . O . . |
$$ | . . O . O . . . . . . . X . . O . . . |
$$ | . . . X O . . . O . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
So here (diagram above) the fun begins! How would you reply to marked stone? If you'd block at
a, then both LZ and KataGo agree that you're making a terrible mistake! KataGo comes up with something much more creative.
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[go]$$Bc Black to play at move 85
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ | . . O . X X X . X . . O . . O O X . . |
$$ | . . . X O O . . . . . . X X O X X . . |
$$ | . X X X X . . . . . . . . O X X . . . |
$$ | . . O O O X X O . . . . O . O X . . . |
$$ | . . . . . O O . . . . . . . . . . . . |
$$ | . X O X . . . . . . . . . . . . . . . |
$$ | . . X . O . . O . . . . . . . X X . . |
$$ | . . . X X X . . . . . . . . X O O O . |
$$ | . . . . . . O . . . . . . . O O . X . |
$$ | . . . O . O . . . . . . . . . . X O . |
$$ | . . X O . . . . . . . . . . . . . X . |
$$ | . . O X . . . . . . . X . O X . X X . |
$$ | . . . . . . . . . . . . . O . . O . . |
$$ | . . O . O . . . X X . . X . . O . . . |
$$ | . . . X O . . X O . . . O O . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
Black to play in the lower left: there's some aji there!
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[go]$$Bc Black to defend at the lower right
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . O . . |
$$ | . . O . X X X . X . . O . . O O X . . |
$$ | . . . X O O . . . . . . X X O X X . . |
$$ | . X X X X . . . . . . . . O X X . . . |
$$ | . . O O O X X O . . . . O . O X . . . |
$$ | . . . . . O O . . . . . . . X . . . . |
$$ | . X O X . . . . . . . . . . . . . . . |
$$ | . . X . O . . O . . . . . . O X X . . |
$$ | . . . X X X . . . . . . . . X O O O . |
$$ | . . . . . . O . . . . . . . O O . X . |
$$ | . . . O . O . . . . . . . . . . X O . |
$$ | . . X O . . . . . . . . . . . W . X . |
$$ | . O O X . . . . . . . X . O X . X X . |
$$ | . O X X . . O . . . . . . O . . O . . |
$$ | . . O X O . . . X X . . X . . O . . . |
$$ | . . O X O . O X O . . . O O . . . . . |
$$ | . . . X . X . X . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]
Move 98: white has just attacked with the marked stone. How would you defend?
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[go]$$Wc Move 181: black pushes into the centre
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . O . . O . |
$$ | . . . . . . . . . O O . . . O O O X . |
$$ | . . O . X X X . X . . O . . O O X . . |
$$ | . . . X O O X . . . X . X X O X X . . |
$$ | . X X X X . . O . O X . X . X X . . . |
$$ | . X O O O X X O . X O O O X . X . . . |
$$ | . . X . . O O . . . . O X . X X O . . |
$$ | . X . X O . . . . . . O X . X X X O . |
$$ | . . X . O . . O . . . . O O O X X O . |
$$ | . . . X X X . . . . . . O X X O O O O |
$$ | . . X . . . O . . a . . . . O O O X X |
$$ | . X O O . O . . . B O . . . . X X . X |
$$ | . O . O . . O . . X . . . . . O X X . |
$$ | . O O X . X O . X . . X . O X O X X . |
$$ | . O X X . X O . . . O O . O O . O X . |
$$ | . . O X O . . O X X X X X O X O . X . |
$$ | . . O X O O O X O . . O O O X . O O . |
$$ | . . O X O X O X . X . X . . O . . . . |
$$ | . . O X X X X . . . . . . X . . . . . |
$$ +---------------------------------------+[/go]
Here, would you block at
a? LZ-258 says yes, after some forcing moves at the bottom. KataGo plays a sequence of moves that look pretty crazy: it seems that white is just throwing away centre territory and getting nothing in return. LZ's evaluations (on 20k playouts per move) rate most of the next few white moves as mistakes (-5% or even -10% for some moves) and by move 213 thinks black is well ahead. But then KataGo's move 214 is better than LZ's best guess, +15%, and now LZ thinks it's 51% in black's favour, so almost as close to a level position as you can get. I'm reminded of the old commentaries where they say "at this point he knew it was going to be a half-pointer". Maybe KataGo, with many many playouts and the ability to estimate score, could see this from move 181?