Tsumego - dead, but WHY??

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Jika
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Re: Tsumego - dead, but WHY??

Post by Jika »

@Knotwilg:

Let's forget about situation 3 and 4. This analysis already points to some confusion between killing and capturing.

I recommend the following page: https://senseis.xmp.net/?KillingVersusCapturing


Thank you for the link (I don't get what he's showing there and I'm deeply impressed by the "beginners game").
In my Go for Beginners book (Otake) there is only "captured", "kill" does not exist:
"If you have occupied all liberties of a stone, the stone is captured and must be taken off the board."

I thought, "killing" means to create a situation when the stones are really taken off the board (remove all liberties).
"Capture" I thought to be creating the situation before that, when both players see that within some moves the stones will be killed anyway, so they do not continue playing until this occurs, but agree that the stones trapped are "dead"?

In our example, if the outside stones are worry free

What does "worry free" mean in Go??

However, in concrete game situations, as you may have experienced, the number of liberties often matters because the outside stones (Black's) are not worry free and may end up captured before they can capture the dead stones inside.


Oh dear.
I have not played any games yet!
"before they can capture the dead stones"... seems I got it wrong above!

https://senseis.xmp.net/?DeadIntroductory
To me it seems confusing why taking a single stone off the board (by occupying its last liberty) is called "captured" there, while taking the white (dead?) group off the board (by occupying their last liberty) is called "kill"...

Is it a bad sign if I'm already feeling dizzy?
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Re: Tsumego - dead, but WHY??

Post by Bill Spight »

This may be redundant, but why not? :)

Click Here To Show Diagram Code
[go]$$B Outer stones safe: White dead
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | . X . O X . .
$$ ---------------[/go]


Why is White dead? Because Black can capture the whole White group.

Click Here To Show Diagram Code
[go]$$B Outer stones safe: White dead
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | 1 X 2 O X . .
$$ ---------------[/go]


:b1: leaves White with only one dame (Dah-meh). We say that White is in atari. But so are the two Black stones, so :w2: captures them.

Click Here To Show Diagram Code
[go]$$B Outer stones safe: White dead
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | 4 3 O O X . .
$$ ---------------[/go]


Next, :b3: puts White into atari. :w4: captures.

Click Here To Show Diagram Code
[go]$$B Outer stones safe, White dead
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | O 5 O O X . .
$$ ---------------[/go]


Finally, :b5: captures the whole group, leaving the next position.

Click Here To Show Diagram Code
[go]$$B Outer stones safe: White captured
$$ | . . . . . . .
$$ | X X X X X . .
$$ | . . . . X . .
$$ | . X . . X . .
$$ ---------------[/go]


Now, the whole point of saying that the original White group is dead, not captured, is that at the end of the game you can simply remove dead stones without having to capture them. :) But the thing is, if you couldn't capture them they would not be dead.

Click Here To Show Diagram Code
[go]$$W Outer stones safe: Who is dead?
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X X .
$$ | B B . O . X .
$$ ---------------[/go]


But what about this situation? Aren't the :bc: stones dead? White to play can capture them.

Click Here To Show Diagram Code
[go]$$W Outer stones safe: Who is dead?
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X X .
$$ | B B 1 O 2 X .
$$ ---------------[/go]


Click Here To Show Diagram Code
[go]$$W Outer stones safe: Who is dead?
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X X .
$$ | . . O O X X .
$$ ---------------[/go]


After :b2: White has two dame. If White makes another play in the corner he puts himself in atari. He does not want to do that, so he is allowed to pass.

Click Here To Show Diagram Code
[go]$$W Outer stones safe: Who is dead?
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X X .
$$ | 5 4 O O X X .
$$ ---------------[/go]

:w3: passes

:b4: puts White in atari, and :w5: captures.

Click Here To Show Diagram Code
[go]$$W Outer stones safe: Who is dead?
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X X .
$$ | O 6 O O X X .
$$ ---------------[/go]


:b6: captures the whole White group, leaving this position.

Click Here To Show Diagram Code
[go]$$W Outer stones safe: White is dead and gone.
$$ | . . . . . . .
$$ | X X X X X . .
$$ | . . . . X X .
$$ | . X . . X X .
$$ ---------------[/go]


Click Here To Show Diagram Code
[go]$$W Outer stones safe: Who is dead?
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X X .
$$ | B B . O . X .
$$ ---------------[/go]


So even in this diagram, even though White can capture the :bc: stones, Black can then turn around and capture the whole White group. So White is dead, not Black. The point is, if play continued, who would end up eliminating the all of the opponent's stones. That player's stones are alive, even if some of them are captured during the process.

Click Here To Show Diagram Code
[go]$$W Outer stones safe: A White phoenix?
$$ | . . . . . . .
$$ | X X X X X . .
$$ | . 7 8 . X X .
$$ | . B . . X X .
$$ ---------------[/go]


So couldn't White continue the fight by playing another stone and eventually capturing the :bc: stone? In theory, sure. But it is obvious that that would be futile. Black does not even have to play :b8:. She could even pass and keep passing and allow White to capture the :bc: stone, and then capture all of the White stones.

Click Here To Show Diagram Code
[go]$$B Outer stones safe: White dead
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | . X . O X . .
$$ ---------------[/go]


OC, White will not bother to play at this point. Resistance is futile. ;)

----

There are also positions where one player could eliminate all of the opponet's stones, but doing so would allow the opponent to make a profit by playing nearby, so he won't capture those stones. In such a case at the end of the game we consider those stones to be alive, too. But we leave such examples for the college course. ;)
Last edited by Bill Spight on Sun May 26, 2019 5:37 am, edited 1 time in total.
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Re: Tsumego - dead, but WHY??

Post by Bill Spight »

Jika wrote:
In our example, if the outside stones are worry free

What does "worry free" mean in Go??


On the internet, nobody can smell your breath. ;)

Sorry, I'm in a jocular mood today. :mrgreen:
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Re: Tsumego - dead, but WHY?? @jlt

Post by jlt »

Jika wrote:
Let me try...
White B1, black D2 - no second eye, white will die?

Click Here To Show Diagram Code
[go]$$Bc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . . . . X . .
$$ | O O O X O . X . .
$$ | . X O . O . X . .
$$ ------------------[/go]


What if White plays at D3 after this?

P.S. "Worry-free" means "cannot be captured".
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Re: Tsumego - dead, but WHY?? @jlt

Post by Jika »

@jlt:

That's what I meant with the last diagram - whoever gets to D3 first wins?

In situation 4


Let me try...
...

White D3, could kill black if black D1 - white has 2 eyes and lives.
So, is this a battle for D3? If black draws first, white can't make two eyes.
Whoever gets to D3 first wins?

Click Here To Show Diagram Code
[go]$$Bc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . O . . X . .
$$ | O O O . O . X . .
$$ | . X . . O . X . .
$$ ------------------[/go]

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Re: Tsumego - dead, but WHY??

Post by jlt »

Click Here To Show Diagram Code
[go]$$Wc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . a . . X . .
$$ | O O O b O . X . .
$$ | . X 1 . O . X . .
$$ ------------------[/go]


I meant: if White plays at C1, then if Black plays at "a" then White plays at "b" and lives, and if Black plays at "b" then White plays at "a" and lives.
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Re: Tsumego - dead, but WHY??

Post by Jika »

@Bill:

Bill Spight wrote:This may be redundant, but why not? :)

Click Here To Show Diagram Code
[go]$$B Outer stones safe: White dead
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | . X . O X . .
$$ ---------------[/go]


Why is White dead? Because Black can capture the whole White group.


Uhm, not to drive you mad, but why is the word "captured" used here?

So, when they are dead, they all can be captured.
When they are captured, they will be taken off the board.
Nobody plays until then because it is futile.

But - when exactly was it that they were "killed"??
Are they "killed" by putting them in a situation so they are dead?
(Makes sense - kill someone and he's dead.)
But after being dead, they can/could be captured (right?).
Who captures (takes as prisoners) dead soldiers??
(What does "capture" mean, literally and/or in Go, remove them from the board, or have them as prisoners who can't escape??)

Maybe it's an Aspergian language problem or I'm just not into warfare...
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Re: Tsumego - dead, but WHY??

Post by Jika »

@jlt:
Fascinating how after seeing this it seems so obvious... :roll:

jlt wrote:
Click Here To Show Diagram Code
[go]$$Wc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . a . . X . .
$$ | O O O b O . X . .
$$ | . X 1 . O . X . .
$$ ------------------[/go]


I meant: if White plays at C1, then if Black plays at "a" then White plays at "b" and lives, and if Black plays at "b" then White plays at "a" and lives.
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Re: Tsumego - dead, but WHY??

Post by Bill Spight »

Jika wrote:@Bill:

Bill Spight wrote:This may be redundant, but why not? :)

Click Here To Show Diagram Code
[go]$$B Outer stones safe: White dead
$$ | . . . . . . .
$$ | X X X X X . .
$$ | O O O O X . .
$$ | . X . O X . .
$$ ---------------[/go]


Why is White dead? Because Black can capture the whole White group.


Uhm, not to drive you mad, but why is the word "captured" used here?


Captured is one of the basic concepts of go. Dead is not. It is a derived concept.

During play, stones are captured by filling all of their dame. At the end of play, there are stones that may be captured, but do not have to be to remove them from the board. These stone are dead. What makes them dead? The fact that they cannot be defended from capture. (As my post indicated, that is not the only requirement, but it is necessary. :))

So, when they are dead, they all can be captured.
When they are captured, they will be taken off the board.
Nobody plays until then because it is futile.


Dead stones are actually taken off the board with capturing them. But only after play has stopped. :)

But - when exactly was it that they were "killed"??


Good question. :) During the game stones may informally be considered alive or dead. But sometimes that turns out not to be so at the end of the game. So during the game we may "kill" some stones, leaving them on the board with the expectation of taking them off the board without capturing them at the end of play. But that is speaking informally. Strictly speaking, stones are not dead or alive until play has stopped.

Are they "killed" by putting them in a situation so they are dead?
(Makes sense - kill someone and he's dead.)


Yes. But they may come back to life before play ends. ;)

But after being dead, they can/could be captured (right?).


That is a necessary condition of being dead.

Who captures (takes as prisoners) dead soldiers??


Nobody. They are removed from the board without capturing them.

(What does "capture" mean, literally and/or in Go, remove them from the board, or have them as prisoners who can't escape??)


You capture stones by taking away all of their dame and removing them from the board.

Maybe it's an Aspergian language problem or I'm just not into warfare...


Asparagus is good for you. :)
Last edited by Bill Spight on Sun May 26, 2019 6:53 am, edited 1 time in total.
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Re: Tsumego - dead, but WHY??

Post by moha »

Jika wrote:
Bill Spight wrote:Why is White dead? Because Black can capture the whole White group.
Uhm, not to drive you mad, but why is the word "captured" used here?
So, when they are dead, they all can be captured.
...
Are they "killed" by putting them in a situation so they are dead?
...
Who captures (takes as prisoners) dead soldiers??
(What does "capture" mean, literally and/or in Go, remove them from the board, or have them as prisoners who can't escape??)

Maybe it's an Aspergian language problem or I'm just not into warfare...
Actually English terms do seem a bit wrong here. Contrary to everyday meaning "captured" or "prisoner" is more dead than "dead" stones that were "killed" (but might still revive later, or need effort to keep them dead).
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Re: Tsumego - dead, but WHY??

Post by Bill Spight »

moha wrote:
Jika wrote:
Bill Spight wrote:Why is White dead? Because Black can capture the whole White group.
Uhm, not to drive you mad, but why is the word "captured" used here?
So, when they are dead, they all can be captured.
...
Are they "killed" by putting them in a situation so they are dead?
...
Who captures (takes as prisoners) dead soldiers??
(What does "capture" mean, literally and/or in Go, remove them from the board, or have them as prisoners who can't escape??)

Maybe it's an Aspergian language problem or I'm just not into warfare...
Actually English terms do seem a bit wrong here. Contrary to everyday meaning "captured" or "prisoner" is more dead than "dead" stones that were "killed" (but might still revive later, or need effort to keep them dead).


There is an analogy in which the English terms make sense. You may have to go to some effort to capture living soldiers, but dead soldiers you can just drag off the field of battle without having to capture them. ;)
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Re: Tsumego - dead, but WHY??

Post by Jika »

Okay, dragging dead soldiers off the battlefield.

My semantic problems revolve around Knotwilg's post,
https://lifein19x19.com/viewtopic.php?p=245208#p245208
(#14, don't know how to use this marker)

The subtle difference between "kill" and "capture".

So moves can be aimed to kill a group (keeping them from making two real eyes) as to capture them later?
And capturing part of a group can help kill the whole group by removing possibilities to form eyes?

Uhm, @Knotwilg, why was it exactly I need to learn this difference?
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Re: Tsumego - dead, but WHY??

Post by jlt »

Here, White is dead but not captured. This means that, even if White plays first, Black can capture White if he wants to.

Click Here To Show Diagram Code
[go]$$Bc White is dead
$$ | . . . . . . . . .
$$ | X X X X X . . . .
$$ | O O O O X . . . .
$$ | . 1 . O X . . . .
$$ ------------------[/go]


However, if Black doesn't pay attention to the surrounding group and lets White play several moves in the area

Click Here To Show Diagram Code
[go]$$Bc Now White is alive and black is dead
$$ | . . . . . . . . .
$$ | O O O O O . . . .
$$ | X X X X X O . . .
$$ | O O O O X O . . .
$$ | . X . O X . . . .
$$ ------------------[/go]


then White becomes alive and Black is dead.
Last edited by jlt on Mon May 27, 2019 1:20 am, edited 1 time in total.
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Re: Tsumego - dead, but WHY??

Post by Jika »

jlt wrote:Here, White is dead but not captured. This means that, even if White plays first, Black can capture White if he wants to.

Click Here To Show Diagram Code
[go]$$Bc White is dead
$$ | . . . . . . . . .
$$ | X X X X X . . . .
$$ | O O O O X . . . .
$$ | . 1 . O X . . . .
$$ ------------------[/go]




So, the "1" move has "killed" white, but until white has been captured, things might change and white might come back to life?
A bit zombie-ish. Better capture them, killing will not suffice, they might still get a chance to eat your brain!

Speaking of brains... mine feels half-eaten now.
Thank you all!
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Re: Tsumego - dead, but WHY??

Post by Bill Spight »

I think part of the problem with understanding dead vs. captured is that you have not played a game. During the play the only way that stones are removed from the board is by being captured. Capturing stones is part of the play. Dead stones are not captured. Removing dead stones is part of the scoring process. Strictly speaking, it is not necessary to remove dead stones to score the game, but it is the usual way to do it.

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


For instance, here is the end of a very unlikely 5x7 game. There are no captured stones. Black has killed the White group on the bottom, and there are two dead stones on the top. We could say that White has killed them, but we usually only talk about killing groups. (Go terminology, like most language, is usually informal, not precise. ;))

We could count the score easily on the small board. Black has 2 pts. for each dead stone in his territory plus 1 pt. for each empty point. That gives him 14 pts. White has 2 pts. for each dead stone plus 1 pt. for each empty point. That gives him 9 pts. Black wins by 5 pts.

But most boards are not so easy to count. In that case we remove the dead stones from Black's territory and put them inside White's territory, and vice versa. We also put the Black stones that White has captured inside Black's territory, and vice versa. Doing so with this board, we have:

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


Now we simply count the empty points. Black has 7, White has 2, so Black wins by 5, as advertised.

Here is the end of a professional game.

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


Only the points, a, b, c, and d, remain to be filled before scoring. (Edit: This game was played in 1950. Today pros normally fill such points during play. Edit2: Oops! White needs to protect at d, doesn't he? ;) That's one reason to fill all those points. :lol: ) White has captured 7 Black stones, Black has captured 3 White stones. There are several dead stones on the board, which you should be able to identify. Black killed a White group in the bottom left.
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