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Offline Bill Spight
 Post subject: Pretty cool endgame problem
Post #1 Posted: Mon Apr 26, 2010 9:57 am 
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The SGF shows a cool endgame problem from the Gokyo Seimyo, based on play in one of Jowa's games. Black to play.



To see the original, cool play by both sides, just play through the file.

My question is, "What is Black's play in the variation for W2?"

Enjoy!

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

Visualize whirled peas.

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Last edited by Bill Spight on Sun Mar 03, 2013 10:37 am, edited 1 time in total.
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Offline fwiffo
 Post subject: Re: Pretty cool endgame problem
Post #2 Posted: Mon Apr 26, 2010 10:56 am 
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Go Diagram
Ko
Click Here To Show Diagram Code
[go]$$B Ko
$$ | . . . . .
$$ | X X X , .
$$ | 4 O X . .
$$ | 3 O O X .
$$ | . 5 O X .
$$ | X . O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------[/go]

Go Diagram
Throw-in not working anymore
Click Here To Show Diagram Code
[go]$$B Throw-in not working anymore
$$ | . . . . .
$$ | X X X , .
$$ | a O X . .
$$ | 3 O O X .
$$ | 4 5 O X .
$$ | X b O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------[/go]

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Offline Bill Spight
 Post subject: Re: Pretty cool endgame problem
Post #3 Posted: Mon Apr 26, 2010 12:29 pm 
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fwiffo wrote:
Go Diagram
Ko
Click Here To Show Diagram Code
[go]$$B Ko
$$ | . . . . .
$$ | X X X , .
$$ | 4 O X . .
$$ | 3 O O X .
$$ | . 5 O X .
$$ | X . O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------[/go]

Go Diagram
Throw-in not working anymore
Click Here To Show Diagram Code
[go]$$B Throw-in not working anymore
$$ | . . . . .
$$ | X X X , .
$$ | a O X . .
$$ | 3 O O X .
$$ | 4 5 O X .
$$ | X b O X .
$$ | 1 O O X .
$$ | O X X O .
$$ | 2 . . O .
$$ | . O . . .
$$ | . . . . .
$$ ---------[/go]


White can do better. :)

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

Visualize whirled peas.

Everything with love. Stay safe.
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Offline Bill Spight
 Post subject: Pretty cool subproblem
Post #4 Posted: Tue Apr 27, 2010 9:40 am 
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Hmmm. Not a lot of people are jumping on this problem. So here is an easier subproblem:



What is White's play after this Black response in the variation?

:)

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

Visualize whirled peas.

Everything with love. Stay safe.


Last edited by Bill Spight on Sun Mar 03, 2013 10:39 am, edited 1 time in total.
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Offline quantumf
 Post subject: Re: Pretty cool endgame problem
Post #5 Posted: Tue Apr 27, 2010 10:06 am 
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White A7

No real defence: If Black A3, White B6, and then lives at A9, or, if black approaches at A9, then white captures the two stones, and if black captures back, white plays B3
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Offline Bill Spight
 Post subject: Re: Pretty cool endgame problem
Post #6 Posted: Tue Apr 27, 2010 11:29 am 
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quantumf wrote:
White A7

No real defence: If Black A3, White B6, and then lives at A9, or, if black approaches at A9, then white captures the two stones, and if black captures back, white plays B3


White can do better. :)

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

Visualize whirled peas.

Everything with love. Stay safe.
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Offline MountainGo
 Post subject: Re: Pretty cool endgame problem
Post #7 Posted: Tue Apr 27, 2010 2:52 pm 
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quantumf wrote:
White A7

No real defence: If Black A3, White B6, and then lives at A9, or, if black approaches at A9, then white captures the two stones, and if black captures back, white plays B3
If Black A3, White can just A9, which gets a couple more points. So Black won't play A3 but rather A9 immediately, which forces White to capture two.
Bill Spight wrote:
White can do better. :)
I continue to be stumped on this, though...
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Offline Bill Spight
 Post subject: Re: Pretty cool endgame problem
Post #8 Posted: Tue Apr 27, 2010 3:01 pm 
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MountainGo wrote:
quantumf wrote:
White A7

No real defence: If Black A3, White B6, and then lives at A9, or, if black approaches at A9, then white captures the two stones, and if black captures back, white plays B3
If Black A3, White can just A9, which gets a couple more points. So Black won't play A3 but rather A9 immediately, which forces White to capture two.
Bill Spight wrote:
White can do better. :)
I continue to be stumped on this, though...


No, you got it right. if B A-03, W A-09, not W B-06. That's how White does better. :)

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

Visualize whirled peas.

Everything with love. Stay safe.
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Offline gonut
 Post subject: Re: Pretty cool endgame problem
Post #9 Posted: Tue Apr 27, 2010 3:29 pm 
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Bill,

Great problem! I obviously don't know the correct answer to your question, because your White move seems to be better than the actual game. And a master wouldn't misplay an endgame, right?

In any event, here's my analysis, which in addition to $5 will get you a latte at a Starbucks:

[sgf-full](;
AB[aj][bj][cj][ck][dl][dm][dn][do][cp][bp]
AW[bk][bl][cl][cm][cn][co][bo][dp][dq][br];
B[an]
(;
W[ao]
C[The actual game.];
B[al];W[am];B[bm];W[bn];B[ak];W[am]
)
(;
W[ap]
C[Bill Spight's question: Black's response?]
(;
B[ao]
C[Best for Black.]
(;
W[am]
C[Best]
(;
B[ak]
C[Sente];
W[bn];B[al]
C[At the end of the game, Black may be able to take another point here. But Black is still a half point worse than in the actual game?]
)
(;
B[aq]
C[A mistake];
W[ak]
C[Black cannot avoid a shortage of liberties.];
B[bn];W[bq];B[ap];W[ar]
)
)
(;
W[bq]
C[Inferior];
B[aq];W[am];B[ak];W[bn];B[al]
C[Black pushes again in sente.]
)
(;
W[ak]
C[A mistake];
B[bm]
C[Black has a seki or a ko.]
)
(;
W[al]
C[A mistake];
B[aq];W[bq];B[ak];W[cq];B[ap];W[ar];B[bn]
C[Seki]
)
(;
W[aq]
C[A mistake.];
B[al]
C[Black has a ko.]
)
)
(;
B[ak]
C[2nd best for Black, but still one point worse for Black than the actual game.];
W[al]
C[Black does end in sente.];
B[aq]
C[Black cannot do any better.];
W[ao]
C[White is safe.]
)
(;
B[aq]
C[Fails];
W[ak]
C[Correct];
B[ao];W[am];B[bn];W[bq];B[ap];W[ar]
)
(;
B[al]
C[Fails];
W[ak]
(;
B[aq];W[am]
)
(;
B[bm];W[bq]
)
(;
B[ao];W[am];B[aq];W[bn]
)
)
)
)[/sgf-full]
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Offline Bill Spight
 Post subject: Re: Pretty cool endgame problem
Post #10 Posted: Tue Apr 27, 2010 10:52 pm 
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gonut wrote:
Bill,

Great problem! I obviously don't know the correct answer to your question, because your White move seems to be better than the actual game. And a master wouldn't misplay an endgame, right?

In any event, here's my analysis, which in addition to $5 will get you a latte at a Starbucks:



Yes, for a while I thought that I had found a better move. ;)



BTW, gonut, are you counting zi? :)

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

Visualize whirled peas.

Everything with love. Stay safe.


Last edited by Bill Spight on Sun Mar 03, 2013 10:41 am, edited 1 time in total.
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Offline gonut
 Post subject: Re: Pretty cool endgame problem
Post #11 Posted: Wed Apr 28, 2010 5:03 am 
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Bill,

Doesn't my SGF above show the refutation of your most recent variation for Black? Viz., after the end of your variation, doesn't White A7 kill all the Black corner stones by keeping the Black stones in a shortage of liberties?

What am I missing?
Please be sure to type slow, I'm old.

And what is "zi"? (I don't really go to Starbucks.)

Myron
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Offline topazg
 Post subject: Re: Pretty cool endgame problem
Post #12 Posted: Wed Apr 28, 2010 5:11 am 
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gonut wrote:
Bill,

Doesn't my SGF above show the refutation of your most recent variation for Black? Viz., after the end of your variation, doesn't White A7 kill all the Black corner stones by keeping the Black stones in a shortage of liberties?

What am I missing?
Please be sure to type slow, I'm old.

And what is "zi"? (I don't really go to Starbucks.)

Myron


I think Black at B7 instead of capturing at A5 is Bill's point ?
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Offline Bill Spight
 Post subject: Re: Pretty cool endgame problem
Post #13 Posted: Wed Apr 28, 2010 6:32 am 
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gonut wrote:
Bill,

Doesn't my SGF above show the refutation of your most recent variation for Black? Viz., after the end of your variation, doesn't White A7 kill all the Black corner stones by keeping the Black stones in a shortage of liberties?


Sorry for not being clear. I meant that Black has a better move than the last one.

Quote:
And what is "zi"? (I don't really go to Starbucks.)

Myron


Myron, I thought that you might be using the Chinese style of counting only Black area. :)

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

Visualize whirled peas.

Everything with love. Stay safe.
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Offline Bill Spight
 Post subject: Re: Pretty cool endgame problem
Post #14 Posted: Wed Apr 28, 2010 6:46 am 
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topazg wrote:
I think Black at B7 instead of capturing at A5 is Bill's point ?


Yes. :)

This ko is lurking in the main line, as well. E. g., B A-06, W A-09, B B-07, W A-07. ;) If White is komaster, White can play that way. But then Black will not start at A-06, either.

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

Visualize whirled peas.

Everything with love. Stay safe.
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Offline gonut
 Post subject: Re: Pretty cool endgame problem
Post #15 Posted: Wed Apr 28, 2010 8:06 am 
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Bill Spight wrote:
topazg wrote:
I think Black at B7 instead of capturing at A5 is Bill's point ?


Yes. :)

This ko is lurking in the main line, as well. E. g., B A-06, W A-09, B B-07, W A-07. ;) If White is komaster, White can play that way. But then Black will not start at A-06, either.


Ah! Now I understand.
Thanks!
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Offline Bill Spight
 Post subject: Subproblem solution
Post #16 Posted: Wed Apr 28, 2010 11:21 am 
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gonuts solved the subproblem. :)



White gets one point more in this variation than in the main variation. :)

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

Visualize whirled peas.

Everything with love. Stay safe.


Last edited by Bill Spight on Sun Mar 03, 2013 10:48 am, edited 1 time in total.
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Offline Bill Spight
 Post subject: Subproblem 2
Post #17 Posted: Wed Apr 28, 2010 11:28 am 
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What is White's play after :b3: in the variation?

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

Visualize whirled peas.

Everything with love. Stay safe.


Last edited by Bill Spight on Sun Mar 03, 2013 10:50 am, edited 1 time in total.
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Offline gonut
 Post subject: Re: Pretty cool endgame problem
Post #18 Posted: Fri Apr 30, 2010 6:11 am 
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Endgames are the worst part of my game, except for joseki, fuseki, middle game, yose, and tsumego. But here goes an attempt to answer Bill's last question anyway...

[sgf-full](;
AB[aj][bj][cj][ck][dl][dm][dn][do][cp][bp][an][aq]
AW[bk][bl][cl][cm][cn][co][bo][dp][dq][br][ap]
(;
W[am]
C[May be best, but depends on the rest of the board?];
B[ak];W[bn];B[al]
C[Black ends in sente.]
)
(;
W[ao]
C[Another possibility.];
B[al]
C[White loses 3 points relative to the main line, and later loses 2 more points capturing the A3 stone. But Black ends in gote.

So this line would be better for White, given at least a 5 point play elsewhere.]
)
)[/sgf-full]
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Offline Bill Spight
 Post subject: Re: Pretty cool endgame problem
Post #19 Posted: Fri Apr 30, 2010 7:39 am 
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gonuts has solved this subproblem too. :)

I have added some comments to his SGF file.



And that means that, along with his earlier work, gonuts has solved the original problem, as well. :) Correct play for Black in it is the atari at A-03, which yields this subproblem.

The end result is the same as in the main line in Gokyo Seimyo, so I did not find an improvement. And that line is cool for both players. However, I thought that the atari (A-03) was pretty cool. The cut (A-05), while it looks natural, loses a dame and, hence, 1 point by comparison. :)

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

Visualize whirled peas.

Everything with love. Stay safe.


Last edited by Bill Spight on Sun Mar 03, 2013 10:51 am, edited 1 time in total.
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Offline Harleqin
 Post subject: Re: Pretty cool endgame problem
Post #20 Posted: Sun May 02, 2010 10:21 am 
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[sgf-full](;AP[another subproblem]CA[ISO8859-1]ST[2]FF[4]SZ[19]GM[1]PB[ ]AB[aj][bj][cj][ck][dl][dm][dn][do][cp][bp]FG[259:]AW[bk][bl][cl][cm][cn][co][bo][dp][dq][br]PW[ ]PM[2]GN[ ]
;B[an]
(;W[am]))[/sgf-full]

What happens here?

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