Shuei endgame question

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Knotwilg
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Shuei endgame question

Post by Knotwilg »

I'd like to combine a few hobby horses here, applying modern endgame theory to a game of Shuei and evaluate it with AI. Myself I've been raised with deiri counting so please bear with me.

The following diagram comes from a no komi game of Shuei (W) against Tamura Yasuhisa, whom I found to be no other than the later Honinbo Shusai, when looking up in SL.
Click Here To Show Diagram Code
[go]$$ Position at move 162
$$ ---------------------------------------
$$ | . . . . . . X X . X . . . . . . . . . |
$$ | . . . . O O O X X . X O . . f X . . . |
$$ | . . . O . O X . X X O O . . O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |
$$ | . . . . . . c . X . . . . . . O O O X |
$$ | . . O . O . . . . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X . O d O O . . . O . . . . . |
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The marked move is the last move played. Locally E is a natural answer but is it also the largest move? I'll try and evaluate moves A through F, plus the obviously small G for a particular reason, and invite you to join in and improve, especially if you can provide the miai values of the moves, but in general where your evaluation differs or just for the fun of exercising. Here we go.

I'll start with G
Click Here To Show Diagram Code
[go]$$W
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X 1 |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
:w1: prevents one point. Next there's a ko. If White captures, Black connects, White connects, that's 2 points better than Black connects, so the value is 2/2 = 1. So the total value of :w1: is 1+1 = 2 gote.
Next A
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | C C . O X . X O O X X . e . . , O . . |
$$ | C C . O X . O d O O . . . O . . . . . |
$$ | 2 O . O X X X O X O O . O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | 1 O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
If Black captures, then either White answers or not. If :w2: then this is the same position as G. From the nominal 6 points A is worth, I subtract 1 for White's 2 point gote follow up (the weak part of my deriri analysis). So it's 5 sente. Or White doesn't answer and Black next destroys the 4 marked points in sente. In this case the value is 6+4 = 10 gote. I find it more straightforward to think of this as a 10 gote move.
B and C are related with each other, which likely makes them smaller individually in terms of follow-up and sort of miai.
Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . X X . X . . . . . . . . . |
$$ | . . . . O O O X X . X O . . f X . . . |
$$ | . . . O . O X 2 X X O O . . O X . . . |
$$ | . . . , O C 1 . . O . . O . O , X . . |
$$ | . . X . C C C O . O O O O . . X . . . |
$$ | . . . O C C C C O X X X . . . . X X X |
$$ | . . . . C 7 5 3 X S . . . . . O O O X |
$$ | . . O . O 6 . 4 . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |[/go]
If White gets to play on both sides, there are about 9 points in this area. Black also has bad aji at the squared point.
Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . X X . X . . . . . . . . . |
$$ | . . . . O O O X X . X O . . f X . . . |
$$ | . . . O . O X . X X O O . . O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |
$$ | . . . . . . 1 . X . . . . . . O O O X |
$$ | . . O . O . . C . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |[/go]
Black fixes the bad aji, makes one or two additional potential points and reduces White's area. Based on the above analysis, I'd say this move is more than 5 gote, perhaps 6, and B is a more than 1 perhaps 2 point White sente move.
Then the ko at D
Click Here To Show Diagram Code
[go]$$ Ko
$$ | . . O . O . . . . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X 3 O 1 O O . . . O . . . . . |
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |[/go]
Black's 5 points have a local tally of 3, so the gote value is 10/3
Then the local answer at E
Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . X X . X . . . . . . . . . |
$$ | . . . . O O O X X . X O . . f X . . . |
$$ | . . . O . O X . X X O O . . O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |
$$ | . . . . . . c . X . . . . . . O O O X |
$$ | . . O . O . . . . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . 1 S S , O . . |
$$ | . . . O X . O d O O C 4 C O . . . . . |
$$ | . O . O X X X O X O O 3 O . . . X . . |
$$ | . X O O X . O X X O X 5 X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The crucial insight here is that :b1: is sente because White's 7 stones can be captured. WHite loses 2 points (squared) but what does Black gain?
Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . X X . X . . . . . . . . . |
$$ | . . . . O O O X X . X O . . f X . . . |
$$ | . . . O . O X . X X O O . . O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |
$$ | . . . . . . c . X . . 7 . . . O O O X |
$$ | . . O . O . . . . . 8 X O O . . . . O |
$$ | . . . . O X . X X . 6 5 X W . . . O . |
$$ | . . . O X . X O O X X . 1 . . , O . . |
$$ | . . . O X . O d O O . 2 . O . . . . . |
$$ | . O . O X X X O X O O 3 O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
:w1: is either sente itself, in which case the move is double sente and of infinite playing value, or gote assuming Black takes his privilege at :b2:
White then captures a stone and reduces Black's area by 1-2 points more, in sente.

I evaluate this as a 5+ point Black sente.
Finally F, which is pretty straightforward.
Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . X X . X 2 1 . . 7 5 6 . . |
$$ | . . . . O O O X X . X O . . 3 X 8 . . |
$$ | . . . O . O X . X X O O . . O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |[/go]
After executing the sente of :w1:, :w3: creates another sente follow-up.
Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . X X . X . . . . . C C . . |
$$ | . . . . O O O X X . X O . a 1 X C . . |
$$ | . . . O . O X . X X O O . . O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |[/go]
:b1: makes a difference of 6 and next A makes another difference of 3.
So I evaluate this as a 7,5 point gote.
Last edited by Knotwilg on Sun May 30, 2021 4:20 pm, edited 2 times in total.
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Re: Shuei endgame question

Post by Knotwilg »

Summary:
A: 10 point gote
B: 1,5 White sente
C: 6 gote
D: 10/3 gote
E: 5,5 Black sente
F: 7 gote
G: 2 gote

With Black to play, I would expect:
Black E
Black A
White F
Black follow up to A
Black C
White B
White D
Black G

As we'll see later, both Shusai and Sheui have different ideas, also because Black's sente at E leaves White with some sente of himself.
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Bill Spight
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Re: Shuei endgame question

Post by Bill Spight »

Knotwilg wrote:Then the ko at D
Click Here To Show Diagram Code
[go]$$ Ko
$$ | . . O . O . . . . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X 3 O 1 O O . . . O . . . . . |
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |[/go]
Black's 5 points have a local tally of 3, so the gote value is 10/3
Click Here To Show Diagram Code
[go]$$ Ko
$$ | . . O . O . . . . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X . O 1 O O . . . O . . . . . |
$$ | . O . O X X X O X O O 3 O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |[/go]
;)

BTW, Elf's recommendation:
Click Here To Show Diagram Code
[go]$$ Sente sequence
$$ | . . O . O . . . . . . X O O . . . . O |
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . 5 . . , O . . |
$$ | . . . O X . O . O O 4 2 6 O . . . . . |
$$ | . O . O X X X O X O O 1 O . . . X . . |
$$ | . X O O X . O X X O X 3 X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |[/go]
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RobertJasiek
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Re: Shuei endgame question

Post by RobertJasiek »

Click Here To Show Diagram Code
[go]$$W
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X 1 |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
You have set modern endgame theory.

Black 1 results in the local count B = R = 2.


Suppose a local gote:

Usually, White has the privilege ko capture, Black connects. The result is 0 local points of territory plus -1 point for the black prisoner stone plus the count 1/3 for the remaining white ko stone, in total, White 1 results in the local count W = 0 + (-1) + 1/3 = -2/3.

The initial tentative gote move value is Mg = (B - W) / 2 = (2 - (-2/3)) / 2 = (2 2/3) / 2 = 1 1/3.


Local position after White 1:

If Black continues, the local count is 1. If White continues, he executes his privilege (sente sequence) ko capture and Black connects, the local count is -2/3. The follow-up has the sente follow-up move value F = 1 - (-2/3) = 1 2/3. The increasing move values Mg < F <=> 1 1/3 < 1 2/3 indicate that the hypothesis of the initial local endgame being a local gote was wrong.


Hence the initial local endgame is a local sente:

White 1 is answered by Black 2 connecting for the resulting local count S = 1. The correct initial sente move value is Ms = R - S = 2 - 1 = 1.


2 EDITs.
Last edited by RobertJasiek on Sun May 30, 2021 8:11 pm, edited 3 times in total.
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Bill Spight
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Re: Shuei endgame question

Post by Bill Spight »

RobertJasiek wrote:
Click Here To Show Diagram Code
[go]$$W
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | . X O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X 1 |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
You have set modern endgame theory.

Black 1 results in the local count B = 2.

White 1 is played in gote and, usually, has White's privilege ko capture, Black connects. The result is 0 local points of territory plus -1 point for the black prisoner stone plus the count 1/3 for the remaining white ko stone, in total, White 1 results in the the local count W = 0 + (-1) + 1/3 = -2/3.

The initial gote move value is (B - W) / 2 = (2 - (-2/3)) / 2 = (2 2/3) / 2 = 1 1/3.

EDIT

WAIT. Why is White 1 played in gote? Is it? Need to verify!
:w1: is a 1 point sente.
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Re: Shuei endgame question

Post by RobertJasiek »

Bill Spight wrote::w1: is a 1 point sente.
Yes, could not edit as fast as you have replied. See my 2nd edit above:)
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Re: Shuei endgame question

Post by John Fairbairn »

Be aware that there is a major back story to this game, part of which is that the result was probably fixed and Shuei deliberately made boundary play errors deliberately to achieve a certain result. See "Games of Shuei".
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Re: Shuei endgame question

Post by Knotwilg »

I'll try modern endgame theory on move A, applying the procedure I learnt from Robert's application on move G (appreciated!)
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | C C . O X . X O O X X . e . . , O . . |
$$ | C C . O X . O d O O . . . O . . . . . |
$$ | C O . O X X X O X O O . O . . . X . . |
$$ | 1 X O O X . O X X O X . X O O . . . . |
$$ | S O X X X X O O X X X . X X O . . O O |
$$ | S X . . X O X X O . . O . X O O O X g |
$$ | S X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
We'll start from this :w1: as reference move. The circled points are White's, the captured stone counts as 1 point. The squared points are neutral.
W = R = 6. The follow-up moves cancel out:
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X . O d O O . . . O . . . . . |
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | O C O O X . O X X O X . X O O . . . . |
$$ | 3 O X X X X O O X X X . X X O . . O O |
$$ | 1 X . . X O X X O . . O . X O O O X g |
$$ | 2 X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
White's follow-up gains another point.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X . O d O O . . . O . . . . . |
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | O . O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | 1 X . . X O X X O . . O . X O O O X g |
$$ | C X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Black's follow-up gains a point for Black. (Black A is sente, as we know)

So we can assess the position as W = R = 6
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | 6 8 . O X . X O O X X . e . . , O . . |
$$ | 5 4 . O X . O d O O . . . O . . . . . |
$$ | 3 O . O X X X O X O O . O . . . X . . |
$$ | 7 X O O X . O X X O X . X O O . . . . |
$$ | 1 O X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Assume local gote. Next Black executes this sente sequence. B = -4
Mg = (6-(-4)/2 = 5

Now look at the position after :b1:
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X . O d O O . . . O . . . . . |
$$ | 1 O . O X X X O X O O . O . . . X . . |
$$ | a X O O X . O X X O X . X O O . . . . |
$$ | X W X X X X O O X X X . X X O . . O O |
$$ | . X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
We now know that A is White's 1 point sente.
B = -4 in sente (captured stone plus two first line points)
W = 4 - 2 = 2 in gote (White saves 4 points of the original count, while Black captures a stone and makes 1 first line point)
F = (2 - (-4))/1 = 6

Since F=6 > Mg=5, the assumption that the original move is gote, is wrong and A is a 5 point Black sente. (Shuei seems to agree: he answered)

Thanks for verifying this exercise!
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Re: Shuei endgame question

Post by RobertJasiek »

Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X . O d O O . . . O . . . . . |
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | O . O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | 1 X . . X O X X O . . O . X O O O X g |
$$ | C X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
For now, just a random thought: you also need to assess if Black 1 is gote or sente.
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Re: Shuei endgame question

Post by Knotwilg »

And on F
Click Here To Show Diagram Code
[go]$$W
$$ ---------------------------------------
$$ | . . . . . . X X . X B W C C 5 3 4 . . |
$$ | . . . . O O O X X . X O C C 1 X 6 . . |
$$ | . . . O . O X . X X O O C C O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |[/go]
We assume the marked sente exchange. We take :w1: as the reference, assuming :w3: is sente. W = R = 6
Click Here To Show Diagram Code
[go]$$B
$$ ---------------------------------------
$$ | . . . . . . X X . X B W . . S C C . . |
$$ | . . . . O O O X X . X O T a 1 X C . . |
$$ | . . . O . O X . X X O O T T O X . . . |
$$ | . . . , O . b . . O . . O . O , X . . |
$$ | . . X . . . . O . O O O O . . X . . . |
$$ | . . . O . . . . O X X X . . . . X X X |[/go]
We asume :b1: local gote, making the 3 circled points. The follow-up at A is gote.
If Black gets it he makes an additional squared point with 50% probability.
f White gets it, she recovers the 3 triangled points, plus makes an extra point and destroys a Black one with 50% probability.

B = -3 + (-1/2+4)/2 = -5/4

Mg = (W-B)/2 = (6+5/4)/2 = 29/8 ~ 4-

We have already calculated F = (-1+3)/2 = 1; Mg > F so the assumption of local gote was correct.

Endgame move is thus a 4 point gote.
Last edited by Knotwilg on Mon Jun 07, 2021 1:04 am, edited 3 times in total.
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Re: Shuei endgame question

Post by Knotwilg »

RobertJasiek wrote:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | . . . O X . X O O X X . e . . , O . . |
$$ | . . . O X . O d O O . . . O . . . . . |
$$ | . O . O X X X O X O O . O . . . X . . |
$$ | O . O O X . O X X O X . X O O . . . . |
$$ | a O X X X X O O X X X . X X O . . O O |
$$ | 1 X . . X O X X O . . O . X O O O X g |
$$ | C X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
For now, just a random thought: you also need to assess if Black 1 is gote or sente.
Well, I can reuse the assessment of G for that purpose, no? You did that for me :)
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Re: Shuei endgame question

Post by Bill Spight »

John Fairbairn wrote:Be aware that there is a major back story to this game, part of which is that the result was probably fixed and Shuei deliberately made boundary play errors deliberately to achieve a certain result. See "Games of Shuei".
Having reviewed a number of pro games with the Elf annotation files, one thing that struck me about this game was the relative lack of definite errors by either player. Shuei may have played safe, and generated small errors that way, but it is not clear that we can call such plays errors. :)

OC, in an 8 dan vs. 3 dan game, simply playing Black is a woefully inadequate handicap. Elf identifies :w46: as an error which brought the game pretty close to par. Then :b47: was a definite error, and Black let the game slip away. The last definite error before the current position was :b71:, but Black may have been lost at that point, anyway. OC, Katago can adjust for the lack of komi. :)
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Re: Shuei endgame question

Post by RobertJasiek »

Knotwilg, you can also reuse G to answer whether Black 1, which is one move esrlier(!!!), is gote or sente. The major effort is still to be done.
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Re: Shuei endgame question

Post by Knotwilg »

RobertJasiek wrote:Knotwilg, you can also reuse G to answer whether Black 1, which is one move esrlier(!!!), is gote or sente. The major effort is still to be done.
Sorry I don't understand. How is analyzing whether A in this diagram (not my original label A) is sente, any different from analyzing if G is sente, which you did, concluding that it is? The positions are equivalent.
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Re: Shuei endgame question

Post by Bill Spight »

Click Here To Show Diagram Code
[go]$$W
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | C C . O X . X O O X X . e . . , O . . |
$$ | C C . O X . O d O O . . . O . . . . . |
$$ | C O . O X X X O X O O . O . . . X . . |
$$ | 1 B O O X . O X X O X . X O O . . . . |
$$ | 5 O X X X X O O X X X . X X O . . O O |
$$ | 4 X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
After :w1:, :b4: is ambiguous. It gains 1 point but then so does :w5:, to stay even. So we may assess the result as 7 points for White.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | C C . O X . X O O X X . e . . , O . . |
$$ | C C . O X . O d O O . . . O . . . . . |
$$ | 2 O . O X X X O X O O . O . . . X . . |
$$ | 4 X O O X . O X X O X . X O O . . . . |
$$ | 1 W X X X X O O X X X . X X O . . O O |
$$ | C X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
After :b1:, if White replies with :w2:, then later :w4: - :b5: connects is a sente sequence. So we can regard this result as net 2 points for White. Assuming :w2: is locally correct, we may regard :b1: as a 5 point sente.
Click Here To Show Diagram Code
[go]$$B :w2: elsewhere
$$ | . . . . O X . X X . . . X W . . . O . |
$$ | 6 8 . O X . X O O X X . e . . , O . . |
$$ | 5 4 . O X . O d O O . . . O . . . . . |
$$ | 3 O . O X X X O X O O . O . . . X . . |
$$ | 7 X O O X . O X X O X . X O O . . . . |
$$ | 1 W X X X X O O X X X . X X O . . O O |
$$ | C X . . X O X X O . . O . X O O O X g |
$$ | . X X X O O O X X X X O . O X X X . X |
$$ | . . . X X O . O O . X X . . . X . X . |
$$ | . . . X O O O . O X . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The standard assumption is that White cannot afford to make a ko with :w4: so this is the standard sente sequence. The result is 3 points for Black.

If the original position is gote, then the swing is between 3 points for Black and 7 points for White. The miai value of the gote is then 5 points. This is exactly the same as the result if the position is a Black sente. So this position is ambiguous between sente and gote, with a miai value of 5 points and a territorial estimate of 2 points for White. :)
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