Re: Solving life-and-death tsumegos by trial and error
Posted: Thu Mar 07, 2013 9:42 am
Great, PeterPeter! 
As others have pointed out, taking note of the exact number of dame can be helpful. (I use the term, dame, because liberty is ambiguous.) Also, in terms of life and death, being cramped is a problem because there is not much space for Black to make two eyes.
So where are Black's potential eyes?
It looks like there is an eye at "a", thanks in part to
. Where is a second possible eye?
A brief inspection suggests that the second eye should include
. That being the case, Black needs to occupy or control point "b", else the eye will be false. Just thinking about eyes suggests "b" as the first move.
Does that move save the two Black stones and capture the stone, forming the second eye?
Yes, thanks to.
Because of its significance in forming the eye in the corner and in saving the two Black stones, I would say that is a key feature of this position.
) If I had tried "c" first and discovered White's counter at "d", "d" would have been my next try.
Although correct endgame is not part of a life and death problem, I think that it can be a good exercise to figure out the best endgame play. In a real game, it is part of the problem.
Bonus question. Where is Black's reply?
You can be more specific.PeterPeter wrote:Black is very cramped, and his 2 stones on the right are in danger.Bill Spight wrote:Here is an example, with black to move and live.
Now, since you have solved this problem, let me ask you a few questions.
What are the key features of this position?
As others have pointed out, taking note of the exact number of dame can be helpful. (I use the term, dame, because liberty is ambiguous.) Also, in terms of life and death, being cramped is a problem because there is not much space for Black to make two eyes.So where are Black's potential eyes?
It looks like there is an eye at "a", thanks in part to
. Where is a second possible eye? A brief inspection suggests that the second eye should include
. That being the case, Black needs to occupy or control point "b", else the eye will be false. Just thinking about eyes suggests "b" as the first move. Does that move save the two Black stones and capture the
stone, forming the second eye? Yes, thanks to
. Because of its significance in forming the eye in the corner and in saving the two Black stones, I would say that
is a key feature of this position. Bill Spight wrote:When you were solving the position, which move looked best at first? Why? What was wrong with it?
Very often, when the opponent has a good play on a point, we also have a good play on that point. (In fact, it is a go proverb.B and C were the first ones I looked at, as killing white's stone would both create space, and help connect. Both of them failed to white playing at D.
) If I had tried "c" first and discovered White's counter at "d", "d" would have been my next try.Bill Spight wrote:After Black's initial correct play, what is White's best play? (From an endgame point of view, OC.
Correct.White should play at F.
Although correct endgame is not part of a life and death problem, I think that it can be a good exercise to figure out the best endgame play. In a real game, it is part of the problem. Bonus question. Where is Black's reply?
Bill Spight wrote:Having solved the problem, can you go through the main variations quickly?
The lines starting with "c" and "b" are also main lines, IMO.Yes, playing D simplifies it a lot.
Bill Spight wrote:Are you confident that you have a reply for every White response?
¡Bueno!Yes.
- 
capture 
takes away the potential eye at 
makes two eyes in the corner.
takes the two Black stones and threatens to make the eye at "a" false, but 
takes back at 
on the main diagonal, spoiling the eye shape. ( 
makes the eye at 