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 Post subject: Re: Reviewing a 1971 Otake game with Kata
Post #21 Posted: Tue Jan 14, 2020 5:56 pm 
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Back to game 3 (sorry, I'm not quite keeping up with the pace here) -- a couple of interesting variations:

Position after move 35:
Click Here To Show Diagram Code
[go]$$Wc White to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . O . . . . . . X . . . |
$$ | . . . . . . X X O . . . . . O . . . . |
$$ | . . . . X X O O X X . . . . . . . . . |
$$ | . X X . X O . b O . . . . . . . O . . |
$$ | . . O . O . O X O . X . . . . . . . . |
$$ | . . . O . . . a . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Here, Otake played at a. I wondered if this was too slow and if white could play in the lower right instead. "Obviously" if white tenukis, black can cut at b. But I had trouble reading out a clear continuation. Here's one possibility, with a little help from LZ-258.

Click Here To Show Diagram Code
[go]$$Wc White tenukis, and then?
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . O . . . . . . X . . . |
$$ | . . . . . . X X O . . . . . O . . . . |
$$ | . . . . X X O O X X . . . . . . . . . |
$$ | . X X . X O 3 2 O . . . . . . . O . . |
$$ | . . O . O . O X O . X . . . 1 . . . . |
$$ | . . . O . . . 4 5 a . c . . . X . . . |
$$ | . . . . b . 8 0 6 7 . . . . . . . . . |
$$ | . . . . . . . . 9 . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Next white a, and black b or c in either order. It looks as though black loses the capturing race but can squeeze on the outside, so on the whole black is ahead (around 60% winrate).

Later, after move 84:
Click Here To Show Diagram Code
[go]$$Bc White's status?
$$ . . . O . . . . . |
$$ O . . . . . . . . |
$$ O X X O X X X X . |
$$ X O O O O X O O . |
$$ . X . . X O . . . |
$$ . . . X X O O O . |
$$ X . . . O B . . . |
$$ . . . . O B . O . |
$$ . . . . . B . X . |
$$ . . . . . . . . . |
$$-------------------+[/go]

It looks to me like white needs one more move to make a living shape. But black can't afford to try and kill, because the circled stones are fragile.

If black does try a blunt attack now:
Click Here To Show Diagram Code
[go]$$Bc Capturing race
$$ . . . O . . . . . |
$$ O . . . . . . . . |
$$ O X X O X X X X . |
$$ B O O O O X O O . |
$$ . B . . B O a 7 3 |
$$ . . . B B O O O . |
$$ B . . . O X 1 2 0 |
$$ . 6 . . O X . O 9 |
$$ . . . . 4 X 5 X 8 |
$$ . . . . . . . . . |
$$-------------------+[/go]

Black can follow up at a and rip off three stones, leaving the rest of the corner as seki -- but black's marked stones probably die.

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 Post subject: Re: Reviewing a 1971 Otake game with Kata
Post #22 Posted: Tue Jan 14, 2020 7:11 pm 
Honinbo

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xela wrote:
Back to game 3 (sorry, I'm not quite keeping up with the pace here) -- a couple of interesting variations:

Position after move 35:
Click Here To Show Diagram Code
[go]$$Wc White to play
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . O . . . . . . X . . . |
$$ | . . . . . . X X O . . . . . O . . . . |
$$ | . . . . X X O O X X . . . . . . . . . |
$$ | . X X . X O . b O . . . . . . . O . . |
$$ | . . O . O . O X O . X . . . . . . . . |
$$ | . . . O . . . a . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Here, Otake played at a. I wondered if this was too slow and if white could play in the lower right instead.


My impulse is to play Otake's move at a, and Elf agrees. :) Maybe more later. :)

Quote:
Later, after move 84:
Click Here To Show Diagram Code
[go]$$Bc White's status?
$$ . . . O . . . . . |
$$ O . . . . . . . . |
$$ O X X O # # # # . |
$$ X O O O O # O O . |
$$ . X . . X O . . . |
$$ . . . X X O O O . |
$$ X . . . O B . . . |
$$ . . . . O B . O . |
$$ . . . . a B . X . |
$$ . . . . . . . . . |
$$-------------------+[/go]

It looks to me like white needs one more move to make a living shape. But black can't afford to try and kill, because the circled stones are fragile.


Without doing any reading myself, I suspect that the weakness of the squared stones is also a factor. In game Honda extended from them to make a base, and then Otake played at a.

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 Post subject: Re: Reviewing a 1971 Otake game with Kata
Post #23 Posted: Mon Jan 20, 2020 12:34 am 
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Up to game 4 now :-) I also did a double-take when I saw the iron pillar at move 19. But what's just as strange (to my eyes) is that LZ-258 wants white to reply not at O7 as in the game, but with the attachment at P7. This leads to a nice tesuji which I was actually able to spot because I've just been looking at the relevant chapter in the Segoe dictionary!

Click Here To Show Diagram Code
[go]$$Bc After this, white has a tesuji
$$ . . . . . . . . |
$$ . . . . O . . . |
$$ . . . 3 4 . . . |
$$ . . 6 2 X 1 . . |
$$ . 9 7 5 8 . . . |
$$ . . . . O . . . |
$$ . . O . O O O . |
$$ . . . X X O X . |
$$ . X . . . X X . |
$$ . . . . . . . . |
$$-----------------+[/go]

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 Post subject: Re: Reviewing a 1971 Otake game with Kata
Post #24 Posted: Mon Jan 20, 2020 3:42 am 
Honinbo

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Speaking of game 4, a brief note about White 126.

KataGo prefers the block at F-09, yielding a 67% winrate for White with 56k rollouts. Elf, in its commentary, also likes F-09, devoting almost 143k rollouts to it and giving it an 79.8% winrate. However, even though Kudo's play, the atari at R-10, is almost entirely off Elf's radar, getting only 4 rollouts, Elf gives it a 77.7% winrate, only 2.1% less than the block. That is well within Elf's margin of error. :) (With only 4 rollouts, Elf does not calculate a winrate directly for R-10, but inherits its winrate from Black 127. Elf does that for any play with fewer than 500 rollouts. :))

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At some point, doesn't thinking have to go on?
— Winona Adkins

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 Post subject: Re: Reviewing a 1971 Otake game with Kata
Post #25 Posted: Mon Jan 20, 2020 7:48 pm 
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Knotwilg wrote:
At 103, Otake seems to misjudge the strength of his stones at the top and in the middle. He attacks for profit on the right side, but White counterattacks, involving Black's groups at the top, on the left and on the right... in the SGF comments: This move loses 8%

This is an interesting one: the various bots disagree here. LZ-258 doesn't find the game move on its own (on 10k playouts), but awards it +1% when shown. Of course LZ-258 thinks komi is 7.5 not 5.5. Trying with KataGo 1.2 and 1.3 (out since you first posted this!): for me, KataGo 1.2 has the game move at -4% (different random number seed?) whereas 1.3 says -7%, setting komi at 5.5. The numbers move around a little if you change komi to 5.0 or to 7.5, but S15 often looks like a possible small loss not a clear mistake. (KataGo disagrees with LZ-258 even on 7.5 komi.) Interestingly, if you set komi to zero, KataGo searches a bit more broadly.

This is also a nice test case for KataGo 1.3's new score estimation (median instead of mean!) Changing the komi between 5.5 and 7.5 makes the score estimate move by about 1.7 or 1.8 points, whereas the same change for KataGo 1.2 results in an almost 4 point change!


This post by xela was liked by: Bill Spight
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