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Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 12:52 am
by Jika
Hi

I'm a complete beginner and I've started tsumego on different apps and websites.

I sometimes get the solution right - but don't know why some group is dead or alive.

I've looked up the shapes (like on senseilibrary)and in a book - but while I get the situation presented there, I'm not able to apply it on tsumego problems:

I try playing on after getting a "correct!" on a problem, but, probably because I make the wrong moves for both sides, the party considered dead can live.

So I think I do not just need a tsumego solver (which the apps having at least one solution), but something that explains HOW the game would go on, and WHY the group is dead.

Any advice?
Thanks a lot!

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 3:08 am
by Bill Spight
I looked here, thinking that you might have posted a diagram that needed explanation.

A player's group is dead if, even when that player plays first, the opponent cannot eventually capture it. (There are groups that are alive even if the opponent can capture a stone or two, but not the group as a whole.) The player may pass, which will sometimes be necessary.

You may enjoy playing the Capture Game, in which the goal is to capture one or more stones. That may give you a better idea of when stones are capturable or not. :)

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 5:16 am
by Mike Novack
And you might initially try the reverse, learn when minimal groups are alive (even when the opponent plays first.

First for the fully connected shapes, then for those that are not fully connected but still alive because all parts touch two different empty spaces. And finally the exceptions ("bent four" is normally alive but by special rule, not in the corner.

Then you can tackle both "live" and "kill" problems because a live problem means being able to reach (no matter what the opponent does) one of these live shapes and a "kill" problem means being able to prevent that.

Finally you can tackle problems that involve "ko" << either live conditionally, kill conditionally, or live in double ko and problems that involve living in seki.

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 6:02 am
by Just Go already
As a beginner, I also had the same frustration a little while ago. For me, the moment of realisation was learning about false eyes in the level up series. What appears initially (to mere beginners like us) as a live group with two eyes can be misleading. If the attacker can make a false eye or you never had 2 real eyes to begin with then the whole group is dead. Without you presenting us an example of a problem, I cannot know for sure that the confusion you are experiencing was the same experience as mine with false eyes, but it could be a possibility.

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 6:04 am
by zermelo
You said you've looked at sensei's library, but I'll put here two links anyway, because they look like relevant material:
https://senseis.xmp.net/?IntroductionToLifeAndDeath
https://senseis.xmp.net/?LifeAndDeath

But it's not very clear to me what kind of situations you find confusing, so would be best you post some examples here.

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 9:28 am
by Bill Spight
Mike Novack wrote:Finally you can tackle problems that involve "ko" << either live conditionally, kill conditionally, or live in double ko and problems that involve living in seki.
Problems where the objective is to live accept seki as a solution. :)

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 11:52 am
by Jika
Sorry, I was not asking about one special situation.

Will learn how to post diagrams to be able to give examples.

I was able to transfer a bent-four-in-the-corner to a problem and got a pass, but I did not see where the ko was...
So, whatever I "solve", I do not learn much from it.

Given the answers on my other thread, I'll try finding easier problems.

Probably this has been posted already in the Beginner's thread, but can someone name good sources for beginners quickly? I'm eager to play :D

Thank you!

PS Are the GoGrinder App's "Basic Problems" basic or too advanced? Cho Chikun's library, part I ? (Those are the ones already confusing me a lot.)

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 12:25 pm
by jlt
If you want really easy tsumegos, try the collections with 1 or 2 stars here: https://tsumego-hero.com/sets

Re: Tsumego - dead, but WHY??

Posted: Sat May 25, 2019 4:40 pm
by Knotwilg
Jika, can you answer the following questions, just to see how much of a beginner you are?
Click Here To Show Diagram Code
[go]$$B Life and death situation 1
$$ | . . . . . . . . .
$$ | X X X X X . . . .
$$ | O O O O X . . . .
$$ | . . . O X . . . .
$$ ------------------[/go]
Can you assess if White is
a) already alive
b) already dead
c) can live or die, depending on who moves first
d) and if c), then where would you play?
Click Here To Show Diagram Code
[go]$$B Life and death situation 2
$$ | . . . . . . . . .
$$ | X X X X X . . . .
$$ | . . . . . X . . .
$$ | O O O O . X . . .
$$ | . . . O . X . . .
$$ ------------------[/go]
Same question here, or on a more abstract level, how is this situation different from the previous one?
Click Here To Show Diagram Code
[go]$$B Life and death situation 3
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | O O O . O X . . .
$$ | . X . . O X . . .
$$ ------------------[/go]
Same as in 1. Can you assess if White is
a) already alive
b) already dead
c) can live or die, depending on who moves first
d) and if c), then where would you play?
Click Here To Show Diagram Code
[go]$$B Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . . . . X . .
$$ | O O O . O . X . .
$$ | . X . . O . X . .
$$ ------------------[/go]
Same question here, and likewise or on a more abstract level, how is this situation different from the previous one?

(You can answer by quoting me and taking the diagrams to add your moves.)

Re: Tsumego - dead, but WHY??

Posted: Sun May 26, 2019 12:07 am
by Jika
If you want really easy tsumegos, try the collections with 1 or 2 stars here: https://tsumego-hero.com/sets
Great, thanks!
Jika, can you answer the following questions, just to see how much of a beginner you are?
Great idea!
Let me try:
Situation 1: dead or alive, depending on who gets the two-eyes-point first (is it A2? Don't know how they are named.)
Situation 2: I have the gut feeling white will live, because much more space to move (don't know the English term; liberties??). But I'm not sure.
Situation 3: White is already dead because he can't close the gap and get A3 at the same time?
Situation 4: see Situation 2.

Will try quoting with diagrams now.

Re: Tsumego - dead, but WHY??

Posted: Sun May 26, 2019 12:11 am
by Jika
Knotwilg wrote:Jika, can you answer the following questions, just to see how much of a beginner you are?
Click Here To Show Diagram Code
[go]$$B Life and death situation 1
$$ | . . . . . . . . .
$$ | X X X X X . . . .
$$ | O O O O X . . . .
$$ | . O . O X . . . .
$$ ------------------[/go]
Can you assess if White is
a) already alive
b) already dead
c) can live or die, depending on who moves first
d) and if c), then where would you play?
Click Here To Show Diagram Code
[go]$$B Life and death situation 2
$$ | . . . . . . . . .
$$ | X X X X X . . . .
$$ | . . . . . X . . .
$$ | O O O O . X . . .
$$ | . X O O . X . . .
$$ ------------------[/go]
Same question here, or on a more abstract level, how is this situation different from the previous one?
Click Here To Show Diagram Code
[go]$$B Life and death situation 3
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | O O O X O X . . .
$$ | . X O . O X . . .
$$ ------------------[/go]
Same as in 1. Can you assess if White is
a) already alive
b) already dead
c) can live or die, depending on who moves first
d) and if c), then where would you play?
Click Here To Show Diagram Code
[go]$$B Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . O . . X . .
$$ | O O O X O . X . .
$$ | . X . . O . X . .
$$ ------------------[/go]
Same question here, and likewise or on a more abstract level, how is this situation different from the previous one?

(You can answer by quoting me and taking the diagrams to add your moves.)

Re: Tsumego - dead, but WHY??

Posted: Sun May 26, 2019 12:29 am
by jlt
@Jika: in situation 2,
Click Here To Show Diagram Code
[go]$$Bc Life and death situation 2
$$ | . . . . . . . . .
$$ | X X X X X . . . .
$$ | b b b b b X . . .
$$ | O O O O b X . . .
$$ | a a a O b X . . .
$$ ------------------[/go]
like in situation 1, as you said in situation 1, if White plays first then White lives by playing at B1. If Black plays first, then Black plays at B1 so White can only get one eye in the "aaa" area. The only place where White could look for a second eye is the "bbbbbbb" area, but this space is too small.

In situation 4
Click Here To Show Diagram Code
[go]$$Bc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . . . . X . .
$$ | O O O . O . X . .
$$ | . X . . O . X . .
$$ ------------------[/go]
please say more who plays first, at which intersection, and what is the result (dead, alive?).

Posted: Sun May 26, 2019 12:43 am
by EdLee
...or you never had 2 real eyes to begin with then the whole group is dead.
Hi Just Go already,
It's more nuanced.
Examples:
  • sometimes, even if you have two real eyes (not false eyes!) for the time being, if either one can be removed (say, in a ko threat), your group can still die;
    Click Here To Show Diagram Code
    [go]$$B :white: can die from ko threat (a)
    $$ | . . . . . . .
    $$ | X X X X X X .
    $$ | O O O O O X .
    $$ | . a . . O X .
    $$ ------------------[/go]
    Click Here To Show Diagram Code
    [go]$$B :white: can die from ko threat (a)
    $$ | . . . . . .
    $$ | X X X X . .
    $$ | . O O X X .
    $$ | O O a O X .
    $$ | . O . O X .
    $$ ------------------[/go]
  • two zero-eye groups can co-exist;
    Click Here To Show Diagram Code
    [go]$$B :bc: & :wc: survive with zero eyes
    $$ | . . . . . . . .
    $$ | O O O . . . . .
    $$ | . O . O . . . .
    $$ | O O O O X X X .
    $$ | B B B O X . X .
    $$ | . . W X . X . .
    $$ | W W W X X X . .
    $$ ------------------[/go]
  • two one-eye groups can co-exist;
    Click Here To Show Diagram Code
    [go]$$B :bc: & :wc: survive, only 1 eye each
    $$ | . . . . . . . . .
    $$ | O O O O . X X . .
    $$ | . O . O X . X X .
    $$ | O O O X X X . X .
    $$ | B B B W W W X X .
    $$ | . B . W . W X . .
    $$ ------------------[/go]
  • more examples of Seki;
  • certain shapes without two real eyes can still survive because of certain ko situations;
  • etc., etc.

Re: Tsumego - dead, but WHY??

Posted: Sun May 26, 2019 3:42 am
by Knotwilg
Jika wrote: Situation 1: dead or alive, depending on who gets the two-eyes-point first (is it A2? Don't know how they are named.)
Situation 2: I have the gut feeling white will live because much more space (liberties)
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

In our example, if the outside stones are worry free, situation 1 and 2 are equivalent. As jlt points out, the extra liberties don't help making extra eyes, so all that matters is the eye shape, which is the same in both situations.

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.

Tsumego often have the tacit assumption that outside stones are worry free. Games don't have such assumptions, you always have to assess the situation and can be surprised by the course of events. This may be the root cause of your confusion.

Re: Tsumego - dead, but WHY?? @jlt

Posted: Sun May 26, 2019 4:08 am
by Jika
jlt wrote:@Jika:

In situation 4
Click Here To Show Diagram Code
[go]$$Bc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . . . . X . .
$$ | O O O . O . X . .
$$ | . X . . O . X . .
$$ ------------------[/go]
please say more who plays first, at which intersection, and what is the result (dead, alive?).
Let me try...
White B1, black D2 - no second eye, white will die?
Click Here To Show Diagram Code
[go]$$Bc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . . . . X . .
$$ | O O O X O . X . .
$$ | . X O . O . X . .
$$ ------------------[/go]
White D2, black C1 - no second eye?
Click Here To Show Diagram Code
[go]$$Bc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . . . . X . .
$$ | O O O O O . X . .
$$ | . X X . O . X . .
$$ ------------------[/go]
White D3, could kill black if black D1 - white has 2 eyes and lives.
So, is this a battle for D3? If black draws first, white can't make two eyes.
Whoever gets to D3 first wins?
Click Here To Show Diagram Code
[go]$$Bc Life and death situation 4
$$ | . . . . . . . . .
$$ | X X X X X X . . .
$$ | . . . O . . X . .
$$ | O O O . O . X . .
$$ | . X . . O . X . .
$$ ------------------[/go]