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Shapes to remember (SDK level)
http://www.lifein19x19.com/viewtopic.php?f=48&t=16894
Page 3 of 3

Author:  jlt [ Sun May 24, 2020 6:51 am ]
Post subject:  Re: Shapes to remember (SDK level)

Finally I got promoted to Tygem 1k, after 17W and 13L. Need to work on elementary tesuji, as I missed the move in the following position.

Position #24: White to play.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . X X X O . O . . . . . . . . . . . . |
$$ | . O O O X O . . . . . . . . . X O O . |
$$ | . . X X X . . . . , . . . O . O X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . , . . . . . , . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . O . O O . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . O . . . . . . . . . . . . O O X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . . . . . , . . . X . X . . . |
$$ | . . . . . X . . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wc Answer
$$ ---------------------------------------
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . X X X O . O . . . . . . . . . . . . |
$$ | . O O O X O . . . . . . . . 3 X O O . |
$$ | . . X X X . . . . , . . . O . O X X . |
$$ | . . . . . . . . . . . . . . . 1 . a . |
$$ | . . . . . . . . . . . . . O . X 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


:w1: threatens a, so Black needs to respond at :b2:, and then :w3: captures the cutting stone.

Author:  Knotwilg [ Sun May 24, 2020 3:15 pm ]
Post subject:  Re: Shapes to remember (SDK level)

It seems that there is freedom in the order of play:

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . X X X O . O . . . . . . . . 2 5 . . |
$$ | . O O O X O . . . . . . . . 1 X O O . |
$$ | . . X X X . . . . , . . . O . O X X . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . O . X 4 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . , . . . . . , . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . O . O O . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . O . . . . . . . . . . . . O O X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . . . . . , . . . X . X . . . |
$$ | . . . . . X . . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$B Black resists
$$ ---------------------------------------
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . X X X O . O . . . . . . . . X 3 1 . |
$$ | . O O O X O . . . . . . . . O X O O 5 |
$$ | . . X X X . . . . , . . . O . O X X . |
$$ | . . . . . . . . . . . . . . . O 4 2 . |
$$ | . . . . . . . . . . . . . O . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . 6 . . X X . . |
$$ | . . . , . . . . . , . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . O . O O . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . O . . . . . . . . . . . . O O X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . . . . . , . . . X . X . . . |
$$ | . . . . . X . . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  Uberdude [ Mon May 25, 2020 2:23 am ]
Post subject:  Re: Shapes to remember (SDK level)

Knotwilg, I wouldn't want to give black the choice to trade corner for side because it makes the top side open and when White gets the corner Black's side group is still not 100% alive (s13).

Author:  Bill Spight [ Mon May 25, 2020 3:41 am ]
Post subject:  Re: Shapes to remember (SDK level)

In the FWIW department, there is also a loose ladder. ;)

Click Here To Show Diagram Code
[go]$$Wc Loose ladder
$$ ---------------------------------------
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . X X X O . O . . . . . 9 8 5 3 . . . |
$$ | . O O O X O . . . . . . 7 6 4 X O O . |
$$ | . . X X X . . . . , . . . O . O X X . |
$$ | . . . . . . . . . . . . . . . 1 . . . |
$$ | . . . . . . . . . . . . . O . X 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . , . . . . . , . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . . . . . . O . O O . |
$$ | . . . . . . . . . . . . . . . O X X . |
$$ | . . O . . . . . . . . . . . . O O X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . . . . . , . . . X . X . . . |
$$ | . . . . . X . . X . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  Knotwilg [ Mon May 25, 2020 5:04 am ]
Post subject:  Re: Shapes to remember (SDK level)

Uberdude wrote:
Knotwilg, I wouldn't want to give black the choice to trade corner for side because it makes the top side open and when White gets the corner Black's side group is still not 100% alive (s13).


I like the first order of moves better too, for the reasons you mention. (But the AI said so!)

Author:  jlt [ Sun May 31, 2020 4:06 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #25. Black to play.

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . X . . . . . . . . . . . . |
$$ | . . X X O X . . . . O . . O O X . . . |
$$ | . . O O O O X . . , . . O X X X . . . |
$$ | . . . . . O O X . . . . . X . . X . . |
$$ | . O X . X . . X . X . . . . . O O . . |
$$ | . O . . . O . . . . . . X . . . . . . |
$$ | . . . X O . O . O . . . . . O . . . . |
$$ | . . . X . . . . . O . . X . . . O . . |
$$ | . . . , X . X . . , . . . . . , . . . |
$$ | . . . . X . . . . O . . . . . . . . . |
$$ | . . O . O . X . . . . . . . . . O . . |
$$ | . X O . . O . . X . . . . . . . . . . |
$$ | . X O . X . . . . . . X X X . X . O . |
$$ | . X O . . . O . X . X . O O . . . . . |
$$ | . . X O . . . . . , . O . . . , X . . |
$$ | . . X O . . O . X . O . . O . X . . . |
$$ | . . . . . . . . . . . . O . O X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Possible variation:

Click Here To Show Diagram Code
[go]$$Bc White is disconnected
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . X . . . . . . . . . . . . |
$$ | . . X X O X . . . . O . . O O X . . . |
$$ | . . O O O O X . . , . . O X X X . . . |
$$ | . . . . . O O X . . . . . X . . X . . |
$$ | . O X . X 3 4 X . X . . . . . O O . . |
$$ | . O . . . O 5 1 . . . . X . . . . . . |
$$ | . . . X O . O 2 O . . . . . O . . . . |
$$ | . . . X . . . . . O . . X . . . O . . |
$$ | . . . , X . X . . , . . . . . , . . . |
$$ | . . . . X . . . . O . . . . . . . . . |
$$ | . . O . O . X . . . . . . . . . O . . |
$$ | . X O . . O . . X . . . . . . . . . . |
$$ | . X O . X . . . . . . X X X . X . O . |
$$ | . X O . . . O . X . X . O O . . . . . |
$$ | . . X O . . . . . , . O . . . , X . . |
$$ | . . X O . . O . X . O . . O . X . . . |
$$ | . . . . . . . . . . . . O . O X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Fri Jun 26, 2020 7:43 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #26: White to play

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . O O O . . O . |
$$ | . . . . . O . . . . . X X X X O O X . |
$$ | . . . O . . . . . , . . . . . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . O X . |
$$ | . . X O . O . . O . . . . . . . . X . |
$$ | . . X O . X O O . O . . . X X X X O . |
$$ | . . X O . X X X O O . O X . O . O O . |
$$ | . . X . X . . . . . . X . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wc Katago's answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . O O O . . O . |
$$ | . . . . . O . . . . . X X X X O O X . |
$$ | . . . O . . . . . , . . . . . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . b . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . 1 . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . O X . |
$$ | . . X O . O . . O . . . . . . . a X . |
$$ | . . X O . X O O . O . . . X X X X O . |
$$ | . . X O . X X X O O . O X . O . O O . |
$$ | . . X . X . . . . . . X . . O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White needs to reduce Black's moyo. White won't have any difficulty escaping since Black will need at some point to spend a move at "a", and since the ponnuki provides some support. In addition, Black's wall doesn't have eyes yet, so Black will also need to defend. White might even get a chance to play a big endgame move at "b" later.

Author:  John Fairbairn [ Fri Jun 26, 2020 9:16 am ]
Post subject:  Re: Shapes to remember (SDK level)

Quote:
I like the first order of moves better too, for the reasons you mention. (But the AI said so!)


Is it possible that what bots show in this sense is unreliable? I am mindful of Bill strictures to remember that bots are only really interested in win rates. In other words, they are interested only in the destination, not how they get there. I assume it may be possible for two lines, one with an inferior move order but where the relevant moves are eventually made nonetheless in both lines, to give the same evaluation (because it's the same end position).

Author:  Bill Spight [ Fri Jun 26, 2020 9:39 am ]
Post subject:  Re: Shapes to remember (SDK level)

John Fairbairn wrote:
Quote:
I like the first order of moves better too, for the reasons you mention. (But the AI said so!)


Is it possible that what bots show in this sense is unreliable? I am mindful of Bill strictures to remember that bots are only really interested in win rates. In other words, they are interested only in the destination, not how they get there. I assume it may be possible for two lines, one with an inferior move order but where the relevant moves are eventually made nonetheless in both lines, to give the same evaluation (because it's the same end position).
(Emphasis mine.)

To be clear, this is about actual win rates, not win rate estimates. I.e., the bots are trained to win games. Humans use the win rate estimates that the bots produce to compare positions and plays.

Author:  jlt [ Tue Jun 30, 2020 10:56 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #26. White to play.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O . X . . . . . . . X O . |
$$ | . . . . X . . . . . O . . . . . X . . |
$$ | . . . . . . . O X . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O . X . . . . . . . X O . |
$$ | . . . . X . . . . . O . . . . . X . . |
$$ | . . . . . . . O X 1 . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  topazg [ Tue Jun 30, 2020 11:53 am ]
Post subject:  Re: Shapes to remember (SDK level)

Trying to get in here before anyone else, as these have looked fun and I've gotten perhaps 40% of them so far!

Click Here To Show Diagram Code
[go]$$Wc Critical groups
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X 2 . 3 . X O . . X O . . |
$$ | . . . O . 1 . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O . X . . . . . . . X O . |
$$ | . . . . X . . . . . O . . . . . X . . |
$$ | . . . . . . . O X . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


These three groups all look critically urgent somehow. Separating Black feels good to me, so my first thought was:

Click Here To Show Diagram Code
[go]$$Wc Cut first, think later!
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X 7 . O . X . . . X O . |
$$ | . . X X . X O 5 X . . . . . . . X O . |
$$ | . . . . X . 3 2 . . O . . . . . X . . |
$$ | . . . . . . 4 O X a . . . . . . . . . |
$$ | . . . , . . . 6 1 , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The problem seems to be simply that :b2: @ a means White hasn't achieved very much. Knowing that there are counter cuts that don't work for Black doesn't mean Black has to go anywhere near them.

Click Here To Show Diagram Code
[go]$$Wc Crude sense of humour
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X 2 . O . X . . . X O . |
$$ | . . X X . X O 1 X 6 8 . . . . . X O . |
$$ | . . . . X . . 5 3 4 O . . . . . X . . |
$$ | . . . . . . . O X 7 . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


This lovely uber-crude line (I tend to use this to identify what I care about the most) just cripples my own top group and doesn't successfully cut anyway, so perhaps something more subtle?

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O a X . . . . . . . X O . |
$$ | . . . . X . b 4 3 5 O . . . . . X . . |
$$ | . . . . . . b O X 1 . . . . . . . . . |
$$ | . . . , . . . . 2 , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]



Click Here To Show Diagram Code
[go]$$Wc Does White win this? Looks ok
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O . X 4 5 . . . . . X O . |
$$ | . . . . X . . 7 3 6 O . . . . . X . . |
$$ | . . . . . . . O X 1 8 b . . . . . . . |
$$ | . . . , . . . . 2 9 a c . . . , . . . |
$$ | . . . X . . . O 0 . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]



Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O . X . . . . . . . X O . |
$$ | . . . . X . . . 4 2 O . . . . . X . . |
$$ | . . . . . . . O X 1 . 5 . . . . . . . |
$$ | . . . , . . . . 3 , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]



Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O . X . . . . . . . X O . |
$$ | . . . . X . . . 2 4 O . . . . . X . . |
$$ | . . . . . . . O X 1 . 5 . . . . . . . |
$$ | . . . , . . . . 3 , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]



Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O 5 X . . . . . . . X O . |
$$ | . . . . X . 3 2 . . O . . . . . X . . |
$$ | . . . . . . . O X 1 . . . . . . . . . |
$$ | . . . , . . . . 4 , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I think these are all probably playable... reading is hard


Click Here To Show Diagram Code
[go]$$Wc My guess
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X . . O . X . . . X O . |
$$ | . . X X . X O . X . . . . . . . X O . |
$$ | . . . . X . . . . . O . . . . . X . . |
$$ | . . . . . . . O X 1 . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  topazg [ Tue Jun 30, 2020 12:28 pm ]
Post subject:  Re: Shapes to remember (SDK level)

@jlt

looking at your hide I realised I'd got the right point this time, but does it succeed in killing the top black group? It looks like it does to me, but if it doesn't, all my justifications for picking the move disappear quite quickly!

Author:  jlt [ Tue Jun 30, 2020 1:12 pm ]
Post subject:  Re: Shapes to remember (SDK level)

@topazg:

Here are two variations shown by KataGo.

Click Here To Show Diagram Code
[go]$$Wc Variation 1
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X 4 . O . X . . . X O . |
$$ | . . X X . X O 3 X 2 5 . . . . . X O . |
$$ | . . . . X . . 9 7 8 O . . . . . X . . |
$$ | . . . . . . . O X 1 0 . . . . . . . . |
$$ | . . . , . . . . 6 , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wcm11 Variation 1, continued
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . a 9 0 . . . . . . |
$$ | . c . O X X X X . . O 8 . . . X O . . |
$$ | . . . O . O X X . O . X W . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X X . O . X . . . X O . |
$$ | . . X X . X O O X X O . . . . . X O . |
$$ | . . . . X . . O O X O . . . . . X . . |
$$ | . . . . . . . O X O X 4 6 . . . . . . |
$$ | . . . , . . . b X 1 3 5 7 . . , . . . |
$$ | . . . X . . . O 2 . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


After a, Black disconnects two groups with b and then White lives in gote with c.
So Black's top group is dead but White is disconnected, cannot save the marked stone and gets a weakish group in the center.

Second variation:

Click Here To Show Diagram Code
[go]$$Wc Second variation
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X O . . X O . . |
$$ | . . . O . O . X O . O X . . . . X O . |
$$ | . . . . X O O X 8 . O . X . . . X O . |
$$ | . . X X . X O 7 X . 0 . . . . . X O . |
$$ | . . . . X . 3 2 . 6 O . . . . . X . . |
$$ | . . . . . . 5 O X 1 . . . . . . . . . |
$$ | . . . , . . . 4 9 , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wcm11 Second variation, continued
$$ ---------------------------------------
$$ | . . . . X . . . . . . . . . . . . . . |
$$ | . . O X . X O O O . . . . . . . . . . |
$$ | . . . O X X X X . . O . . . . X O . . |
$$ | . . . O . O X X . O . X W . . X O . . |
$$ | . . . O . O . X O . O X 5 . . . X O . |
$$ | . . . . X O O X X . O 3 X . . . X O . |
$$ | . . X X . X O O X 2 X 4 . . . . X O . |
$$ | . . . . X . O X 1 X O . . . . . X . . |
$$ | . . . . . . O O X O . . . . . . . . . |
$$ | . . . , . . . X O , . . . . . , . . . |
$$ | . . . X . . . O . . . . . . . . . . . |
$$ | . . X . . . . O X . . . . . . . . . . |
$$ | . . . O . . . O X . . . . . . . O . . |
$$ | . . X O . . X O X . . . . . . O X . . |
$$ | . . X O . O O X . . . . . . . . O . . |
$$ | . . X , . . O X . , . . . . . O . . . |
$$ | . . . . O O X X X O . . . X . X X . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


So White doesn't kill Black but is connected, saves the marked stone and has a strong position in the center.

Needless to say, reading these variations is very difficult, but at least I can try to add the clamp :w1: to my library of shapes.

Author:  jlt [ Tue Jul 14, 2020 3:34 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #27: Black to play

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . O . . . . . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . X X X X X X . . . . . . . . . . . . |
$$ | . O O , . . . . . , . . . . . O . . . |
$$ | . . . O . O X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . O . . . . . . . . . . . . . . . |
$$ | . . . . . O . . . . . . . . . . . . . |
$$ | . X X X X X X . . . . . . . . . . . . |
$$ | . O O , . . . . . , . . . . . O . . . |
$$ | . . . O 2 O X . . . . . . . . . . . . |
$$ | . . . 4 1 3 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Mon Aug 17, 2020 7:32 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #28: Black to play.

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . O X O . . . . . . . . O . O . O X O |
$$ | . X O O O X . X . X O O X O O O X O . |
$$ | X . X O . X . . . X O X X X X X X O . |
$$ | . X X O . . O . . . X . X O . O O X . |
$$ | X . X O O . . . . . . X X . O . O X . |
$$ | . X O X O X . . . O X . . . . . X . . |
$$ | . O O X X O O O O X X O X . . . X . . |
$$ | . O X X . X X O X O O . O . . . . . . |
$$ | . . O , . . . X X O . O . . . , . . . |
$$ | . . O . . O X . . X O . . . . X . . . |
$$ | . . . . . . . . . X . . . . . . . . . |
$$ | . . . . . . . . . . . O . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . O O . . . . . . . . . . . . X . . . |
$$ | . X O O O . . . . , . . . . . , . . . |
$$ | . X X X X O . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Bc Answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . O X O . . . . . . . . O . O . O X O |
$$ | . X O O O X . X . X O O X O O O X O . |
$$ | X . X O . X . . . X O X X X X X X O . |
$$ | . X X O . . O . . . X . X O . O O X . |
$$ | X . X O O . . 1 . . . X X . O . O X . |
$$ | . X O X O X . . . W X . . . . . X . . |
$$ | . O O X X W W W W X X O X . . . X . . |
$$ | . O X X . X X W X O O . O . . . . . . |
$$ | . . O , . . . X X O . O . . . , . . . |
$$ | . . O . . O X . . X O . . . . X . . . |
$$ | . . . . . . . . . X . . . . . . . . . |
$$ | . . . . . . . . . . . O . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . O O . . . . . . . . . . . . X . . . |
$$ | . X O O O . . . . , . . . . . , . . . |
$$ | . X X X X O . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The white stones are captured.

Author:  jlt [ Fri Aug 21, 2020 5:28 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #29: Black to play. At this point I didn't know where to play but actually not much imagination was needed.

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . . X O . |
$$ | . . X , X . . . . , . . . . . X . O . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . O . . . . . . . . . . |
$$ | . . X . X O . X X O . . . . . X X . . |
$$ | . . X . X O X X O O . . . . . . O . . |
$$ | . O X O X X O O X , . . . . . O . . . |
$$ | . X O X X O X O . . . . . O . . . . . |
$$ | . O O O O O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Bc Cut!
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . . X O . |
$$ | . . X , X . . . . , . . . . . X . O . |
$$ | . . . . . . . . . . . . . . . . 0 . . |
$$ | . . . . . . . . . . . . . . . 9 O . . |
$$ | . . . . . . . . . . . . . . . . 7 8 . |
$$ | . . . . . . . . . . . . . . . . 5 6 . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . 3 . . . . . . . . . |
$$ | . . . . . X . . O 1 2 . . . . . . . . |
$$ | . . X . X O . X X O a 4 . . . X X . . |
$$ | . . X . X O X X O O . . . . . . O . . |
$$ | . O X O X X O O X , . . . . . O . . . |
$$ | . X O X X O X O . . . . . O . . . . . |
$$ | . O O O O O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Of course I saw the cut, but my wrong reasoning was that after :b3:, White would continue pushing and thus weaken the stones on the right of the board. But in fact, White needs to come back and defend the cutting point "a", thus giving Black the time to reinforce Q10. :b5:, :b7: and :b9: force White to crawl on the second line while building a moyo.

Click Here To Show Diagram Code
[go]$$Bcm11 Black forces White to live small while making territory
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X . . X O . |
$$ | . . X , X . . . . , . . . . . X . O . |
$$ | . . . . . 9 . . . . . . . . . . O . . |
$$ | . 5 . 8 . . . . . . . . . . . X O . . |
$$ | . 6 2 . 3 . . . . . . . . . . . X O . |
$$ | . . . . . . . . . . . . . . . . X O . |
$$ | . . . . 7 . . . . . . . . . . . . O . |
$$ | . . 4 , . . . . . 1 . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . X . . . . . . . . . |
$$ | . . . . . X . . O X O . . . . . . . . |
$$ | . . X . X O . X X O a O . . . X X . . |
$$ | . . X . X O X X O O . . . . . . O . . |
$$ | . O X O X X O O X , . . . . . O . . . |
$$ | . X O X X O X O . . . . . O . . . . . |
$$ | . O O O O O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Mon Sep 07, 2020 2:30 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Position #30: White to play. Katago considers several moves, but I am mainly interested in the upper-right quadrant.

Click Here To Show Diagram Code
[go]$$Wc White to play in the upper-right quadrant
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O . . . . . . . X O O . . . . |
$$ | . . X , . . . . . , . . X X O O O . . |
$$ | . . X O . . . . . . . . . O O X X X . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X X X . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . X . . . . . . . . . . O . . X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . O O X . |
$$ | . . X . . . . . . . . . . . . O X . . |
$$ | . X . . . . . . . . . . . . . O X . . |
$$ | . O X X O . . . . X . . . . . O O O . |
$$ | . O O O X X X . . . . . . X . . . . . |
$$ | . . . O O X . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Katago's answer:

Click Here To Show Diagram Code
[go]$$Wc answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O . . . . . . . X O O . . . . |
$$ | . . X , . . . . . a . . X X O O O . . |
$$ | . . X O . . . . . . . . . O O B B B . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . B B B . 1 . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . X . . . . . . . . . . O . . X . |[/go]


(a move at "a" would also be good).

This move threatens the marked black group, so Black needs to defend.

Click Here To Show Diagram Code
[go]$$Wc answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O . . . . . . . X O O . . . . |
$$ | . . X , . . . . . , . . X X O O O 0 . |
$$ | . . X O . . . . . . . . . O O X X X . |
$$ | . . . O . . . . . . . . . . 7 . . . . |
$$ | . . X . . . . . . . . . . . . . 6 4 . |
$$ | . . . . . . . . . . . . . X X X 5 1 . |
$$ | . . . . . . . . . . . . . . O 8 . . . |
$$ | . . . , . . . . . , . . . . . 2 O O . |
$$ | . . . X . . . . . . . . . . O 3 9 X . |[/go]


Click Here To Show Diagram Code
[go]$$Wcm11 answer, continued
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 5 2 . |
$$ | . . . . O . . . . . . . X O O . 3 1 4 |
$$ | . . X , . . . . . , 7 . X X O O O X . |
$$ | . . X O . . . . . . . . . O O X X X . |
$$ | . . . O . . . . . . . . . . O 6 . . . |
$$ | . . X . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . X X X O O . |
$$ | . . . . . . . . . . . . . . O X . . . |
$$ | . . . , . . . . . , . . . . . X O O . |
$$ | . . . X . . . . . . . . . . O O O X . |[/go]


At some point, Black needs to connect with :b16:, which gives White a chance to pincer the top three stones. The pincering stone :w17: is at the same time an extension for the wall E17. If Black wants to save the three stones N16, then White will launch a splitting attack, which is effective since Black's top right group is not yet completely alive.

In the game, I simply blocked at S16. This is not a good move because Black can now defend the three stones and at the same time pincer White's wall:

Click Here To Show Diagram Code
[go]$$Wc White's mistake
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O . . . 2 . . . X O O . . . . |
$$ | . . X , . . . . . , . . X X O O O 1 . |
$$ | . . X O . . . . . . . . . O O X X X . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X X X . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . X . . . . . . . . . . O . . X . |[/go]


Even if White plays S12 afterwards, Black will ignore and continue the attack on White's wall:

Click Here To Show Diagram Code
[go]$$Wc White's mistake
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O . 4 . 2 . . . X O O . . . . |
$$ | . . X , . . . . . , . . X X O O O 1 . |
$$ | . . X O . . . . . . . . . O O B B B . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X X X . 3 . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . X . . . . . . . . . . O . . X . |[/go]


White could capture the marked black stones with an extra move, but that's not big because White has already spent a move with :w1:, so Black can sacrifice the three stones.

Back to the original move suggested by Katago: what if :b2: jumps into the corner?

Click Here To Show Diagram Code
[go]$$Wc alternative (bad) response by Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . O . . . . . . . X O O . . 2 . |
$$ | . . X , . . . . . , . . X X O O O . . |
$$ | . . X O . . . . . . . . . O O X X X . |
$$ | . . . O . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X X X . 1 . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . X . . . . . . . . . . O . . X . |[/go]


Click Here To Show Diagram Code
[go]$$Wc alternative (bad) response by Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . b . |
$$ | . . . . O . . . . . . . X O O . . 2 . |
$$ | . . X , . . . . . , 8 . X X O O O 3 4 |
$$ | . . X O . . . . . . . . 7 O O X X X . |
$$ | . . . O . . . . . . . . . . . 6 . . . |
$$ | . . X . . . . . . . . . . . . a 5 . . |
$$ | . . . . . . . . . . . 9 . X X X . 1 . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . X . . . . . . . . . . O . . X . |[/go]


White is out in the center, while Black doesn't have any eye yet. In case of emergency, White can make a base at any time with "b".

Author:  jlt [ Thu Oct 08, 2020 8:31 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #31: White to play.

The solution is pretty easy, but I keep making the same kind of mistake.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X O . . . . . X O O X . . . . . |
$$ | . . . X O . . O . . X . . X . X . . . |
$$ | . . X , . . . . . X X O O X . , . . . |
$$ | . . . . . . . O . X O O X X . X X . . |
$$ | . . . X . . . . . X O O O O O O O . . |
$$ | . . . . . . O O . X X . . . . . . . . |
$$ | . . . . . . O X X . . O O . . X . . . |
$$ | . . . . . . O X . . O . O . . . . . . |
$$ | . . . , . . . O X , . O X . X , X . . |
$$ | . . . . . . . . . X . . X . . . . . . |
$$ | . . . . . . . . . . O . . . X . O . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$Wc Solution
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X O . . . . . X O O X . . . . . |
$$ | . . . X O . . O . . X . . X . X . . . |
$$ | . . X , . . . . . X X O O X . , . . . |
$$ | . . . . . . . O . X O O X X . X X . . |
$$ | . . . X . . . . . X O O O O O O O . . |
$$ | . . . . . . O O . X X . . . . . . . . |
$$ | . . . . . . O X X . . O O . . X . . . |
$$ | . . . . . . O X . . O . O . . . . . . |
$$ | . . . , . . . O X , . O X . X , X . . |
$$ | . . . . . . . . . X a . X . . . . . . |
$$ | . . . . . . . . . . O 1 b . X . O . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


In the game I simply played "a", but it's better to connect with a "forcing move" like :w1:. Strictly speaking, :w1: is not forcing because even if Black doesn't respond, White won't push at "b" immediately. Still, the option is left for later.

Author:  jlt [ Mon Oct 12, 2020 8:38 am ]
Post subject:  Re: Shapes to remember (SDK level)

I am now playing on my 1k Fox account again. So far I am doing well with 7W 2L. The last win wasn't completely deserved, as my opponent resigned early after I killed a small group and got an 86% advantage.

Anyway, here is a position from the game.

Position #32 : Black to play in the upper-left quadrant. Several good moves are possible, try to find one.

Click Here To Show Diagram Code
[go]$$Bc Black to play in the upper-left quadrant
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . X . . . . . . . . X . X O . . |
$$ | . . O , . X . O . , X . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . X O . |
$$ | . . . O . X . O . . O . . . . . X O . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . X . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . O . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


(I am specifying "upper left quadrant" becase Katago says that Black may also tenuki and invade at the 3-3 point.)

Click Here To Show Diagram Code
[go]$$Bc answer 1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . X . . . . . . . . X . X O . . |
$$ | . . O , . X . O . , X . . . . X O . . |
$$ | . . . . . . . 2 1 . . . . . . . X O . |
$$ | . . . O . X . O . . O . . . . . X O . |
$$ | . . . . . . . . . 3 . . . . . . X . . |
$$ | . . . O . X . 4 . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . a . . . . . , . . . |
$$ | . . . . . . . . . . O . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The sequence :b1: :w2: :b3: weakens the white group. Even if the black stones :b1: and :b3: are only loosely connected, White is weak enough so that after :w4:, Black can afford to tenuki at "a".

Even if White adds a move at some point, Black has several possibilities to reinforce his group, like

Click Here To Show Diagram Code
[go]$$Bc Possible continuation
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 5 . . . . . . . . . . . X O O . . |
$$ | . 2 1 . X . . . . . . . . X . X O . . |
$$ | . . O 3 . X . O . , X . . . . X O . . |
$$ | . . 4 . . . . O X . . . . . . . X O . |
$$ | . . . O . X . O . W O . . . . . X O . |
$$ | . . . . . . . . . X . . . . . . X . . |
$$ | . . . O . X . O . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


or

Click Here To Show Diagram Code
[go]$$Bc Other possible continuation
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . X . . . . . . . . X . X O . . |
$$ | . . O , . X . O . , X . . . . X O . . |
$$ | . . . . . . . O X . . . . . . . X O . |
$$ | . . . O . X . O . W O . . . . . X O . |
$$ | . . . 6 . . . . . X . . . . . . X . . |
$$ | . . . O 5 X . O . . . . . . . . . . . |
$$ | . . 2 1 . . . . . . . . . . . . . . . |
$$ | . . 4 3 . . . . . , . . . . . , . . . |
$$ | . . . 7 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


Instead of :w4: in the first diagram, White may want to continue like this:

Click Here To Show Diagram Code
[go]$$Bc Other response by White
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . a . X . . . . 4 5 . . X . X O . . |
$$ | . . O , . X . O . , X . . . . X O . . |
$$ | . . . . . . . 2 1 . . . . . . . X O . |
$$ | . . . O . X . O . 7 O . . . . . X O . |
$$ | . . . . . . . . 6 3 . . . . . . X . . |
$$ | . . . O . X . . 9 8 . . . . . . . . . |
$$ | . . . b . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . O . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The fight is complicated but Black has nothing to fear since he has moves like "a" or "b" to strenghen his group, while White's group also has weaknesses.

In the first diagram, another way for Black to play is

Click Here To Show Diagram Code
[go]$$Bc answer 2
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . X . . . . . . . . X . X O . . |
$$ | . . O , . X . O . , X . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . X O . |
$$ | . . . O . X . O . . O . . . . . X O . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . O . X . . . . . . . . . . . . . |
$$ | . 4 2 1 . . . . . . . . . . . . . . . |
$$ | . . 3 5 . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . O . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


(there are more complicated variations).

Instead of :w2:, White may also want to cut

Click Here To Show Diagram Code
[go]$$Bc answer 2 - other variation, less good for White than the previous one
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . X . . . . . . . . X . X O . . |
$$ | . . O , . X . O . , X . . . . X O . . |
$$ | . . . . . . . . . . . . . . . . X O . |
$$ | . . . O . X . O . . O . . . . . X O . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . 8 O 2 X 5 . . . . . . . . . . . . |
$$ | . . 7 1 3 4 . . . . . . . . . . . . . |
$$ | . . . , . 6 . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 9 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . O . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Now both players have two weak groups, but Black's position looks a bit better since Black's groups have access to the edge, and one of Black's groups separates two white groups.

Author:  jlt [ Fri Nov 27, 2020 6:37 am ]
Post subject:  Re: Shapes to remember (SDK level)

After 13 wins in a row I got double-promoted to 2 dan on Fox. Did the ranks recently become weaker on that server? I am still 3k on IGS... and stuck at 6k on OGS. Anyway here is a position from last game. Black is trying to survive in the lower left corner.

Position #33, Black to play.

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X X O O . . |
$$ | . . . . O X . . . . . . . O . X O . . |
$$ | . . . O . X . . . X . X . X X X X X . |
$$ | . . . . . . . . . . . X O X O X X O . |
$$ | . . O . . . . . . . O O X X O X O O . |
$$ | . . . . . . . . . . . . O O O X O . . |
$$ | . . . . . . . . . . . . . . O O O . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . X O . . |
$$ | . . X . . . . . . . . . . . X . X X . |
$$ | . . . . . . . . . . . . . . . X O O X |
$$ | . O O O X . . . . . . . . . . X . O . |
$$ | . X X X O O . . . . . . . . . X O . . |
$$ | . . . O X X . . . X . . . . . X O . . |
$$ | . . . O O X . . . . . . X . . X O . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The first move is "straightforward" (even if I didn't find it in my game).
Click Here To Show Diagram Code
[go]$$Bc answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X X O O . . |
$$ | . . . . O X . . . . . . . O . X O . . |
$$ | . . . O . X . . . X . X . X X X X X . |
$$ | . . . . . . . . . . . X O X O X X O . |
$$ | . . O . . . . . . . O O X X O X O O . |
$$ | . . . . . . . . . . . . O O O X O . . |
$$ | . . . . . . . . . . . . . . O O O . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . X O . . |
$$ | . . X . . . . . . . . . . . X . X X . |
$$ | . . . . . . . . . . . . . . . X O O X |
$$ | . O O O X . . . . . . . . . . X . O . |
$$ | . X X X O O . . . . . . . . . X O . . |
$$ | . . . O X X . . . X . . . . . X O . . |
$$ | . 1 . O O X . . . . . . X . . X O . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black increases its liberties and tries to kill one of the three surrounding groups. Many continuations are possible depending on White's answer, here is one which is not optimal for White but illustrates what may happen.

Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . X X O O . . |
$$ | . . . . O X . . . . . . . O . X O . . |
$$ | . . . O . X . . . X . X . X X X X X . |
$$ | . . . . . . . . . . . X O X O X X O . |
$$ | . . O . . . . . . . O O X X O X O O . |
$$ | . . . . . . . . . . . . O O O X O . . |
$$ | . . . . . . . . . . . . . . O O O . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . O . . . . . , . . . . . , . . . |
$$ | . . O . . . . . . . . . . . . X O . . |
$$ | . . X . . . . . . . . . . . X . X X . |
$$ | . 9 . . 7 . . . . . . . . . . X O O X |
$$ | . O O O X . . . . . . . . . . X . O . |
$$ | . X X X O O 8 . . . . . . . . X O . . |
$$ | . 5 . O X X . . . X . . . . . X O . . |
$$ | . 1 4 O O X . 0 . . . . X . . X O . . |
$$ | . 2 3 6 . . . . . . . . . . X O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:b7: threatens to capture two white stones in a net, so :w8: extends. Then :b9: wins the capturing race. White can also capture three stones with :w10: but takes gote.

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