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Corner races study
http://lifein19x19.com/viewtopic.php?f=15&t=15338
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Author:  lightvector [ Mon Dec 25, 2017 11:20 pm ]
Post subject:  Corner races study

Recently, I completed a study of some corner capturing races, shoring up a hole in my understanding of how to evaluate the fighting liberties and ko resources present in different kinds of non-two-eyed corner groups.

For example:

Click Here To Show Diagram Code
[go]$$B Do you know the status of this capturing race?
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . X X X O O O O X . .
$$ | X O O O X X X X X . X
$$ | . O . X . . . . . . .
$$ | . . O X . X . . . . .
$$ | . . O O . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . O . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Click Here To Show Diagram Code
[go]$$B Or this one?
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . . X O O O O X . . .
$$ | . X X O X X . X . . X
$$ | X O O X . . . X . . .
$$ | . O . X . X . . . . .
$$ | . . O O . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . O . . . . . . . .
$$ | . . . . . . . . . . .[/go]


Click Here To Show Diagram Code
[go]$$B Or this one?
$$ ----------------------
$$ | . . . . . . . . . . .
$$ | . . X X O O O O X . .
$$ | . X X O X X . . X . X
$$ | . O O O O X . X . . .
$$ | . . . . . X . . . . .
$$ | . . O . . . . . . . .
$$ | . . . . . . . . . . .
$$ | . . O . . . . . . . .
$$ | . . . . . . . . . . .[/go]


In the process of learning how the fighting sequences in these corners worked, I ended up creating several dozen capturing race problems. In case anyone else is interested, here is the SGF with all the problems. I designed it offline in CGoban, so I don't know how well it actually works in Eidogo - feel free to try it either way or in any other sgf editor.

Warning: There may be mistakes in this problem set! I'm just a lowly dan player, and my reading is far from perfect :). Many of these problems could be very hard if you are weaker than strong SDK, indeed many were quite hard for me. If you find a mistake, let me know.

EDIT: Fixed a glitch in the SGF that caused Eidogo to erroneously display "Black to play" in some of the problems. They are all status problems and should be solved from both sides.

Attachment:
cornerrace.sgf [19.45 KiB]
Downloaded 439 times


Author:  fycj [ Tue Dec 26, 2017 5:27 am ]
Post subject:  Re: Corner races study

Really nice, thanks

Author:  Bill Spight [ Tue Dec 26, 2017 3:35 pm ]
Post subject:  Re: Corner races study

Good topic, good research. :) Bravo! :clap:

Some analysis of one of the semeai.



Highlights:

Wonderful things happen on the 1-2 point.

The ko threat situation often affects how to play.

Author:  lightvector [ Tue Dec 26, 2017 5:19 pm ]
Post subject:  Re: Corner races study

Thanks Bill! What a complicated endgame situation :mrgreen: I did find the small-corner-with-hane positions to actually be some of the hardest. Good reading practice. :study:

Author:  Bill Spight [ Thu Dec 28, 2017 1:19 pm ]
Post subject:  Re: Corner races study

I looked at another semeai, and posted some comments here. viewtopic.php?f=12&t=12327&p=226407#p226407

:)

Author:  dhu163 [ Wed Oct 13, 2021 6:04 pm ]
Post subject:  Re: Corner races study

Some nice analysis by lightvector. I looked through the whole file and added some comments.



I only disagreed with one conclusion: MLO-B3

Edit:
However I missed the 2-1 tesuji which Bill mentions in his link. This move seems best in several of the positions with a hane but I didn't see it.

Attachments:
corner races.sgf [32.72 KiB]
Downloaded 135 times

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