Life In 19x19
http://www.lifein19x19.com/

Shapes to remember (SDK level)
http://www.lifein19x19.com/viewtopic.php?f=48&t=16894
Page 7 of 8

Author:  Knotwilg [ Wed Apr 06, 2022 1:49 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 8 7 3 5 . . . . . |
$$ | . . X O . . . O d . 6 X W 4 . X O . . |
$$ | . . X O . . . . . c X O 1 . . X O . . |
$$ | . X O O . . . . . . b 2 9 . . X . . . |
$$ | . X . . . . . . . . e a 0 . . . . O . |
$$ | . . X . O X . . . . . . . . O . O . . |
$$ | . . . X O . . . . . . . . . . . . . . |
$$ | . . O X O . X . . . . . . . . . . . . |
$$ | . . . X O . . . . , . . X O O O . . . |
$$ | . . X . O . . . . . O O O X X X . . . |
$$ | . . . O . X . . . . O X X . . . . . . |
$$ | . X O . . . . . . . . . . X . . . . . |
$$ | . X . X . . . . . . . X . . . . O . . |
$$ | . . . X . . . . . O . . . . . . . . . |
$$ | . . X , O . . . . O X . . O O O . . . |
$$ | . . . X O . . O O X X . X X O X O O . |
$$ | . . . . . . . . . O X . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Anything allowing White to solidly connect looks wrong, so ...

Not that I read it but White can't hane at :w10: because of the ladder. So probably :w8: is better as a lateral stretch.

Author:  jlt [ Thu Apr 07, 2022 7:22 am ]
Post subject:  Re: Shapes to remember (SDK level)

Hint
Don't play 1-2-3, just play 3.

Katago's main line
Click Here To Show Diagram Code
[go]$$Bc Katago's main line (11 at a and 12 at b)
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 3 . 1 . . . . . . |
$$ | . . X O . . . O . . 7 X O a . X O . . |
$$ | . . X O . . . . b 6 X O 2 . . X O . . |
$$ | . X O O . . . . 9 5 4 . . . . X . . . |
$$ | . X . . . . . . . 8 0 . . . . . . O . |
$$ | . . X . O X . . . . . . . . O . O . . |
$$ | . . . X O . . . . . . . . . . . . . . |
$$ | . . O X O . X . . . . . . . . . . . . |
$$ | . . . X O . . . . , . . X O O O . . . |
$$ | . . X . O . . . . . O O O X X X . . . |
$$ | . . . O . X . . . . O X X . . . . . . |
$$ | . X O . . . . . . . . . . X . . . . . |
$$ | . X . X . . . . . . . X . . . . O . . |
$$ | . . . X . . . . . O . . . . . . . . . |
$$ | . . X , O . . . . O X . . O O O . . . |
$$ | . . . X O . . O O X X . X X O X O O . |
$$ | . . . . . . . . . O X . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


The triple hane :b1: is not natural for me but it works, even if White solidly connects, White can't disconnect the two black groups. The fate of the stones :b5: and :b9: is not clear, they may be sacrificed.

Further comments
If Black cuts first, Katago's main line is the following, and is 3 points worse:
Click Here To Show Diagram Code
[go]$$Bc Black cuts first
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . 6 5 . . . . . . |
$$ | . . X O . . . O . . 4 X O 3 . X O . . |
$$ | . . X O . . . . . , X O 1 . . X O . . |
$$ | . X O O . . . . . . . 2 . . . X . . . |
$$ | . X . . . . . . . . . . . . . . . O . |
$$ | . . X . O X . . . . . . . . O . O . . |
$$ | . . . X O . . . . . . . . . . . . . . |
$$ | . . O X O . X . . . . . . . . . . . . |
$$ | . . . X O . . . . , . . X O O O . . . |
$$ | . . X . O . . . . . O O O X X X . . . |
$$ | . . . O . X . . . . O X X . . . . . . |
$$ | . X O . . . . . . . . . . X . . . . . |
$$ | . X . X . . . . . . . X . . . . O . . |
$$ | . . . X . . . . . O . . . . . . . . . |
$$ | . . X , O . . . . O X . . O O O . . . |
$$ | . . . X O . . O O X X . X X O X O O . |
$$ | . . . . . . . . . O X . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Knotwilg's idea is 7 points worse than the main variation.
Click Here To Show Diagram Code
[go]$$Bc Other variation
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . 7 3 5 . . . . . |
$$ | . . X O . . . O . 8 6 X O 4 . X O . . |
$$ | . . X O . . . . . , X O 1 9 . X O . . |
$$ | . X O O . . . . . . . 2 . . . X . . . |
$$ | . X . . . . . . . . . . . . . . . O . |
$$ | . . X . O X . . . . . . . . O . O . . |
$$ | . . . X O . . . . . . . . . . . . . . |
$$ | . . O X O . X . . . . . . . . . . . . |
$$ | . . . X O . . . . , . . X O O O . . . |
$$ | . . X . O . . . . . O O O X X X . . . |
$$ | . . . O . X . . . . O X X . . . . . . |
$$ | . X O . . . . . . . . . . X . . . . . |
$$ | . X . X . . . . . . . X . . . . O . . |
$$ | . . . X . . . . . O . . . . . . . . . |
$$ | . . X , O . . . . O X . . O O O . . . |
$$ | . . . X O . . O O X X . X X O X O O . |
$$ | . . . . . . . . . O X . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Note that Black finishes in gote.

Author:  Knotwilg [ Thu Apr 07, 2022 9:43 am ]
Post subject:  Re: Shapes to remember (SDK level)

Your main line has two 6's and 7's.

Click Here To Show Diagram Code
[go]$$Bc Katago's main line
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 3 . 1 4 0 8 . . . |
$$ | . . X O . . . O . . . X O 5 6 X O . . |
$$ | . . X O . . . . . . X O 2 7 9 X O . . |
$$ | . X O O . . . . . . . a b d . X . . . |
$$ | . X . . . . . . . . . . c e . . . O . |
$$ | . . X . O X . . . . . . . . O . O . . |
$$ | . . . X O . . . . . . . . . . . . . . |
$$ | . . O X O . X . . . . . . . . . . . . |
$$ | . . . X O . . . . , . . X O O O . . . |
$$ | . . X . O . . . . . O O O X X X . . . |
$$ | . . . O . X . . . . O X X . . . . . . |
$$ | . X O . . . . . . . . . . X . . . . . |
$$ | . X . X . . . . . . . X . . . . O . . |
$$ | . . . X . . . . . O . . . . . . . . . |
$$ | . . X , O . . . . O X . . O O O . . . |
$$ | . . . X O . . O O X X . X X O X O O . |
$$ | . . . . . . . . . O X . . . X X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I missed this ladder earlier.

Author:  jlt [ Thu Apr 07, 2022 10:05 am ]
Post subject:  Re: Shapes to remember (SDK level)

I corrected the diagram.

Author:  jlt [ Wed Apr 27, 2022 12:09 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Position #68, Black to play. Find the next few moves.

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

Author:  lightvector [ Wed Apr 27, 2022 2:59 pm ]
Post subject:  Re: Shapes to remember (SDK level)

This position feels a bit unusual, because it seems Black may have missed the typical joseki move in the upper right? Unless there is a different sequence that leads to that result.

In the joseki I know that results in a shape like the upper right, normally Black plays a hane at R18 instead of merely extending at Q18. White blocks, Black connects, then White needs to add another move to not die, which is usually at S13.

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


Although I guess it's a little uncommon regardless that white still gets to play this clamp much later, as it is common for black to add a defense here to stop the clamp.

Anyways, it may be instructive to compare and contrast how Black should handle White's clamp in the perhaps-more-standard shape, as follows:

Click Here To Show Diagram Code
[go]$$Bc Black to play here, as a contrast/complement to jlt's position
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X X . . . . . . . . . . X X O . |
$$ | . . O X O X X . . . . . . . . X O . . |
$$ | . . . O O O X . . , . . . . . X O . . |
$$ | . . . . . . O X . . . . . W X O O . . |
$$ | . . O . . . O X . . . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . X . O . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . O . . . . . . . . . . X . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Thu Apr 28, 2022 12:58 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Indeed I (Black) missed the hane-connect (R18 - S18 - Q18), instead I played Q18 and White answered with R18.

In the problem position, Katago expects this

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


so Black sacrifices three stones and makes a strong, connected group.

Lightvector's position doesn't exist since Black has made an extra move, so I'll remove a few stones

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

Author:  lightvector [ Fri Apr 29, 2022 8:29 am ]
Post subject:  Re: Shapes to remember (SDK level)

Yep,
It's interesting that small difference in strength of the black stones makes the difference between wanting to sacrifice them or not... but also in the variation where black got the hane, the winrate/score are only slightly better than sacrificing in the original game!

@jlt - the position I posted should exist, no? Black doesn't have an extra move.

Black got 1 stone at R18, white lost the stone at R18 but got extra stone at S18 and S13. So it's still exactly balanced in moves made by each side.

Author:  jlt [ Fri Apr 29, 2022 12:30 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Oops sorry, I didn't read your preceding diagram carefully.

Interestingly, Katago expects yet another variation

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


and then Black plays a. I can't say I really understand why Black O18 is preferred in one variation and N17 in another.

Author:  jlt [ Mon May 16, 2022 2:16 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #69, another elementary shape that I missed. Not really a big mistake but an illustration of the fact that some simple moves are still missing in my brain policy network. Black to play.

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


Answer:
Click Here To Show Diagram Code
[go]$$Bc this is slightly better than the solid connection
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . X X O . O . |
$$ | . . . X . . . . . , . . . . . X O . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . 1 . . . . . . . . . X X X . . O . . |
$$ | . . X O . . . . . . . . O O O . . . . |
$$ | . X W X X . . X . . . . . . . . . . . |
$$ | X O O . X . . . . . . . . . . . . . . |
$$ | X X O O O X . O . , . . . . . , . . . |
$$ | . O . . . . O O X . . X O . . . O . . |
$$ | . O O . . O O X . X X O O O . . . . . |
$$ | . X . . O . X . X . X O O X . . . . . |
$$ | . . X X X . . . . X O X X X . O O . . |
$$ | . X O O . . . . . X O O O X . O X . . |
$$ | . . X O . O X X . , . O X O O , X . . |
$$ | . . X O . X O O X X . O X X X X . . . |
$$ | . . X X O O . . O O . O . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  jlt [ Sat May 28, 2022 2:59 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #70, Black to play a good endgame move.

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

Author:  Akura [ Sat May 28, 2022 4:54 am ]
Post subject:  Re: Shapes to remember (SDK level)

First, my eyes were drawn to a, but then I thought that b may be good?

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

Author:  jlt [ Sat May 28, 2022 10:53 am ]
Post subject:  Re: Shapes to remember (SDK level)

'b' was indeed the correct move:

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


White can cut later at 'a' but Black will sacrifice 2 stones and both parts will live separately.

If Black doesn't play there then later White can play 'a' below. This threatens the cut 'b' which is much more severe than in the previous diagram.

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

Author:  EricBackus [ Sun May 29, 2022 4:03 pm ]
Post subject:  Re: Shapes to remember (SDK level)

What about trying to cut off the D12 white stones, by playing:
Click Here To Show Diagram Code
[go]$$Bc Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . O X . X . . . . . . |
$$ | . . . . O . . O X X O X . X . . . . . |
$$ | . . . O X O O O O X O O X X . . X X . |
$$ | . . O , X . . O X O O O . . . X . O . |
$$ | . . X X . . X X X X . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . O . . . . . . . . . . . . . |
$$ | . . . O . 1 O . X X X . X . . . . . . |
$$ | . O O X X . . O O O O X X O . . O . . |
$$ | . . X O X O . . . , . O X . . , . . . |
$$ | . . X . X O . X O . . O X . . O . . . |
$$ | . . . X X X X X O O O X X O . . . . . |
$$ | . . . X O O X O . . X X . . O . O . . |
$$ | . . X O . . O . O . . . . O X X O . . |
$$ | . X O O . . . . . . . . . . X O X . . |
$$ | . X X O O . . . . , . . . . . , X . . |
$$ | . X . X O . O . . O X X . . . X . . . |
$$ | . . X . . . . . O . O X . X . . . . . |
$$ | . . . . . . . . . . O O X . . . . . . |
$$ ---------------------------------------[/go]

I suppose it must not work, but in my first glance at it, it looked promising...

Author:  jlt [ Sun May 29, 2022 9:52 pm ]
Post subject:  Re: Shapes to remember (SDK level)

From my kyu perspective, White would just sacrifice two stones, which is not so big:

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


but the AI thinks it's a wrong sequence for White because the weakness C17 is still there, so the following is a much better move
Click Here To Show Diagram Code
[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . O X . X . . . . . . |
$$ | . . . . O . . O X X O X . X . . . . . |
$$ | . . . O X O O O O X O O X X . . X X . |
$$ | . 4 O , X . . O X O O O . . . X . O . |
$$ | . 2 X X . . X X X X . . . . . . . . . |
$$ | 7 3 5 . 8 . . . . . . . . . . . O . . |
$$ | . 6 O . 0 O . . . . . . . . . . . . . |
$$ | . . . O 9 1 O . X X X . X . . . . . . |
$$ | . O O X X . . O O O O X X O . . O . . |
$$ | . . X O X O . . . , . O X . . , . . . |
$$ | . . X . X O . X O . . O X . . O . . . |[/go]


Black cannot cut immediately because White threatens to kill A14 so...

Click Here To Show Diagram Code
[go]$$Bcm11
$$ ---------------------------------------
$$ | . . . . . . . . . O X . X . . . . . . |
$$ | . . 2 . O . . O X X O X . X . . . . . |
$$ | . . . O X O O O O X O O X X . . X X . |
$$ | . O O 1 X . . O X O O O . . . X . O . |
$$ | . O X X . 3 X X X X . . . . . . . . . |
$$ | X X X . O . . . . . . . . . . . O . . |
$$ | . O O . O O . 4 . . . . . . . . . . . |
$$ | . . . O X X O . X X X . X . . . . . . |
$$ | . O O X X . . O O O O X X O . . O . . |
$$ | . . X O X W . . . , . O X . . , . . . |
$$ | . . X . X W . X O . . O X . . O . . . |[/go]


Now, Black could capture the two marked stones but it's not very big at the moment.

Author:  EricBackus [ Mon May 30, 2022 10:56 am ]
Post subject:  Re: Shapes to remember (SDK level)

jlt wrote:
From my kyu perspective, White would just sacrifice two stones, which is not so big

Yea, it was just bad reading on my part.

Author:  jlt [ Sat Jun 11, 2022 4:29 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #71, White to play.

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

Author:  EricBackus [ Sat Jun 11, 2022 1:46 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Originally I thought of P9, but I don't think it works. So instead, maybe G14 to reduce the liberties of the black dragon in the middle. However, even assuming the dragon dies, I worry that black lower left is just too big.

Author:  jlt [ Sat Jun 11, 2022 2:59 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Hint: the last move was
S14

Continue in the area.

Answer:

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


The point is to protect against the clamp S11 while gaining liberties in order to win the capturing race against H15. THe black group S16 will need to add defensive moves.

Author:  jlt [ Tue Jul 26, 2022 2:44 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #72, White to play a good endgame move.

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

Page 7 of 8 All times are UTC - 8 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/