Yet another old problem

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Bill Spight
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Yet another old problem

Post by Bill Spight »

Maybe this one is easier, or maybe not. ;)
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O . . . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | . X X O X O O O O |
$$ | . X X . O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X . . . . . . . |
$$ -------------------[/go]
Edit: Sorry, no komi. Jigo is not a win. ;)

Enjoy! :)

OC, feedback welcome. :)
Last edited by Bill Spight on Sat Feb 05, 2011 7:38 am, edited 1 time in total.
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Toge
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Re: Yet another old problem

Post by Toge »

Bill Spight wrote:
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 5 X X O X O O O O |
$$ | 7 X X 3 O O X X X |
$$ | 9 X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 4 6 8 0 . . . |
$$ -------------------[/go]
Reasons:
1. 1 point in sente with possibility to spoil 2 points in gote
2. Gote saving 2 points + also makes alley pushing not really sente
3. Gote which also makes the same 2 points
4. Next black of course runs the longer alley. Alleys have point values which approach 2 points, but never reach it. (reminds me of Zeno's paradox)
5. White runs alley which is now longer

White wins by komi (0,5 points).
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HermanHiddema
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Re: Yet another old problem

Post by HermanHiddema »

@Toge: there is no komi.
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O a b . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 3 X X O X O O O O |
$$ | 5 X X 1 O O X X X |
$$ | 7 X O O O X . X . |
$$ | 9 X X X O X X X X |
$$ | 0 X O O O O O O O |
$$ | . X 2 4 6 8 c . . |
$$ -------------------[/go]
:w11:, :b12:, :w13: at a, b, c.

W1 keeps the option open of killing Black with a move at E9, if both corridors are destroyed. That means that the end of the black corridor is now sente, increasing its size to 2, and now the "longer corridor rule" no longer applies. If black does persist in playing the longer corridor, :b10: is mandatory, otherwise black dies. Then White can play the a-b exchange before taking tedomari at c.

White wins by 1 point.
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Mnemonic
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Re: Yet another old problem

Post by Mnemonic »

Arg, this problem is too complex. Maybe I haven’t learned anything :sad: Every time I see a sequence and try starting to write it down I notice how black can counter :sad:

My conclusions so far:
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 3 X X O X O O O O |
$$ | 4 X X 5 O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 6 7 . . . a a |
$$ -------------------[/go]
:w1: and :b2: are a must, I don't see any sequence that works for either player if they miss these plays. Now, if black blocks at 4 he loses, but if he takes the stone at 5, Whites only option is to start pushing down the black corridor. If black does likewise, white will get the last play and make the two marked points in the corner. It should be Jigo.
So 3 is a mistake and white should play it at 5?
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | . X X O X O O O O |
$$ | . X X 3 O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 4 . . . . . . |
$$ -------------------[/go]
:b4: ruins whites chances. If he blocks he will reach a jigo. Trying to push down the corridors doesn't work because they are now the same length. Yes, white ends with sente, but there are no plays left and trying to change the sequence will just allow black to get some huge plays like 1.

This problem has me stumped. I really tried to read it all out, but I just don't see this working for white :sad:
While I was teaching the game to a friend of mine, my mother from the other room:
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Re: Yet another old problem

Post by Magicwand »

feedback:
this time i was more careful and spent close to 1 min to analize and check my initial thought.
my initial thought is correct and white win my 1.
very intresting problems.
you should write a book on endgame and publish it using such examples.
if it is too much problem publishing it, at least pdf it and sell it to the member in L19.
"The more we think we know about
The greater the unknown"
Words by neil peart, music by geddy lee and alex lifeson
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Bill Spight
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Re: Yet another old problem

Post by Bill Spight »

Mnemonic wrote:
Arg, this problem is too complex. Maybe I haven’t learned anything :sad: Every time I see a sequence and try starting to write it down I notice how black can counter :sad:

My conclusions so far:
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 3 X X O X O O O O |
$$ | 4 X X 5 O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 6 7 . . . a a |
$$ -------------------[/go]
:w1: and :b2: are a must, I don't see any sequence that works for either player if they miss these plays. Now, if black blocks at 4 he loses, but if he takes the stone at 5, Whites only option is to start pushing down the black corridor. If black does likewise, white will get the last play and make the two marked points in the corner. It should be Jigo.
So 3 is a mistake and white should play it at 5?
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | . X X O X O O O O |
$$ | . X X 3 O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 4 . . . . . . |
$$ -------------------[/go]
:b4: ruins whites chances. If he blocks he will reach a jigo. Trying to push down the corridors doesn't work because they are now the same length. Yes, white ends with sente, but there are no plays left and trying to change the sequence will just allow black to get some huge plays like 1.

This problem has me stumped. I really tried to read it all out, but I just don't see this working for white :sad:
Now you know what does not work. :)

Hint:
Question your assumptions.
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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Bill Spight
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Re: Yet another old problem

Post by Bill Spight »

Magicwand wrote:feedback:
this time i was more careful and spent close to 1 min to analize and check my initial thought.
my initial thought is correct and white win my 1.
very intresting problems.
you should write a book on endgame and publish it using such examples.
if it is too much problem publishing it, at least pdf it and sell it to the member in L19.
Thank you, Magicwand. :)

I am glad you find them interesting. I had thought that the lack of tesuji made them relatively uninteresting, but I am rethinking that. And after all, if I don't write such a book, who will? ;)
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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Re: Yet another old problem

Post by Mnemonic »

@ Bill Spight
Sorry, I've already looked at Herman Hiddema's solution. (I never thought about killing the black group because it had _so_ much eye space. So I looked at D5 as first move and concluded that black could just take the 3 points on top and that would ruin anything I could do :( )
Other question: Would you allow me to copy your problem and show it to my club? (I don't want to try and sell it or profit from it or anything :))

If you do decide to write that book I will definitely get me a copy :tmbup:
While I was teaching the game to a friend of mine, my mother from the other room:
"Cutting? Killing? Poking out eyes? What the hell are you playing?"
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Re: Yet another old problem

Post by lorill »

A6 & C1 are miai, so the problem is to decide whether D9 or D5 first.

if we play D5, black D9, result is jigo. If we play D9 first, either black take or protect, white does the other one, and wins by 1.
Edit: after reading the other posts, i see why i'm wrong.
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Bill Spight
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Re: Yet another old problem

Post by Bill Spight »

@ Mnemonic
Mnemonic wrote:
Other question: Would you allow me to copy your problem and show it to my club? (I don't want to try and sell it or profit from it or anything :))
Sure, please do. :)

I once set it up on a spare board for some pros and they liked it. :)
If you do decide to write that book I will definitely get me a copy :tmbup:
Many thanks. :) I do plan to write it.
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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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jts
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Re: Yet another old problem

Post by jts »

Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O a . . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | c X X O X O O O O |
$$ | . X X b O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X d . . . . . . |
$$ -------------------[/go]
A is 2pt with a 2 pt follow-up, B is 2pts, the corridors starting with C and D both sum to slightly less than 2 (D being worth more). White wants to start with A; that makes B and the followup miai, so then W gets the last 2 pt move. After that, B gets (in effect) 1 pt; after his move at D the corridors are the same length and W and B will have to get equal points from them.
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 6 X X O X O O O O |
$$ | . X X 3 O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 4 5 . . . . . |
$$ -------------------[/go]
No, that's jigo. I think B and W have to get the same number of points on the bottom, but I'll try it this way...
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 5 X X O X O O O O |
$$ | 7 X X 3 O O X X X |
$$ | 9 X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 4 6 8 0 . . . |
$$ -------------------[/go]
Oh I see, there's some sort of L&D issue, isn't there? If we change up the order of play, then B will have to blink first on the corridor.
Click Here To Show Diagram Code
[go]$$Wc White to play and win - F1 is 11
$$ -------------------
$$ | O . O 2 . . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 3 X X O X O O O O |
$$ | 5 X X 1 O O X X X |
$$ | 7 X O O O X . X . |
$$ | 9 X X X O X X X X |
$$ | 0 X O O O O O O O |
$$ | . X 4 6 8 1 . . . |
$$ -------------------[/go]
-1 :D
Click Here To Show Diagram Code
[go]$$Wc White to play and win
$$ -------------------
$$ | O . O 2 . . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 3 X X O X O O O O |
$$ | 5 X X 1 O O X X X |
$$ | 7 X O O O X . X . |
$$ | 9 X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 4 6 8 0 . . . |
$$ -------------------[/go]
Click Here To Show Diagram Code
[go]$$W11c White to play and win
$$ -------------------
$$ | O . O X 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | O X X O X O O O O |
$$ | O X X O O O X X X |
$$ | O X O O O X . X . |
$$ | O X X X O X X X X |
$$ | 1 X O O O O O O O |
$$ | . X X X X X 3 . . |
$$ -------------------[/go]
-2
This problem was a lot of fun! Probably great for a 10k.
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mw42
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Re: Yet another old problem

Post by mw42 »

I thought this problem was harder. My first attempt I got jigo, so I sat down and thought about it. (I know I also got your first problem wrong, but that was only because of a silly mistake! :oops: )

Please, let me know if I made any errors in my solution for this problem.
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Bill Spight
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Re: Yet another old problem

Post by Bill Spight »

@ mw42

You solved the problem, but the calculations are a bit tricky. I'll post them later. :)
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

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Re: Yet another old problem

Post by mw42 »

Bill Spight wrote:@ mw42

You solved the problem, but the calculations are a bit tricky. I'll post them later. :)
:grumpy: I look forward to the post. I've never done endgame problems before so these are certainly a learning experience.
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Re: Yet another old problem

Post by daal »

Bill Spight wrote:Maybe this one is easier, or maybe not. ;)
Click Here To Show Diagram Code
[go]$$Wc
$$ -------------------
$$ | O . O 1 d . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | b X X O X O O O O |
$$ | . X X c O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X a . . . . . . |
$$ -------------------[/go]
I think 1 is the biggest, because if black doesn't answer it, a further move at d takes away two points. Since nothing else is bigger, 1 is sente. Of the remaining points, I will boldly claim that c is worth one point. A and b are...tunnels and the longer the tunnel the more it's worth due to some cumulative factor. How much? I forget, but I think more than one. Thus:
Click Here To Show Diagram Code
[go]$$Wc
$$ -------------------
$$ | O . O 1 2 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 5 X X . X O O O O |
$$ | 6 X X 4 O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 3 . . . . . . |
$$ -------------------[/go]
Looks like a done deal.


ARRGh. I forgot to count the prisoner. Next try:
.
.
.
Three tries later, white always loses or jigo. Conclusion 1 is wrong. The long tunnel must be the biggest. First I will strain my brain to figure out what a is really worth:

"a" is worth an average of the end result of black or white playing it. If black plays it, he gets 3 points. If white plays it, we still don't know the end result, which depends on whether black or white plays on d. If black plays on d, black gets 2 points. If white plays on d, black gets 0 points. This averages to 1 point. How to leverage this? 'a' is worth 3 or 1 from black's perspective. Thus it is worth 2 points. :-? (I suspect this is wrong - please mark my errors in red).
Click Here To Show Diagram Code
[go]$$Wc
$$ -------------------
$$ | O . O a d . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | b X X O X O O O O |
$$ | . X X c O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 1 . . . . . . |
$$ -------------------[/go]
Following the logic (?) above, 1 is worth an average of 6 and whatever, which makes it worth more than a. :-? :roll: :-? :-? This is not accurate, but appears to lead to a win.
Click Here To Show Diagram Code
[go]$$Wc
$$ -------------------
$$ | O . O 3 4 . X O . |
$$ | . O O X . X X O O |
$$ | O O X X X X X O . |
$$ | 2 X X O X O O O O |
$$ | . X X 5 O O X X X |
$$ | . X O O O X . X . |
$$ | . X X X O X X X X |
$$ | . X O O O O O O O |
$$ | . X 1 . . . . . . |
$$ -------------------[/go]
feedback welcome. :)
Even if I got it wrong, having fewer options than the last problem made me willing to tackle it.
Patience, grasshopper.
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