Problems that ask for the status of a group are NO part of my work.

Additionally, Bill's problem is out of range of my current activity. Currently, I am still busy with one-move life-and-death-problems (not very acute; you know -- the boring effect), due to the backlash of failure variations in three- and five-move problems.

_________________
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

Good point. A lot of people have a blind spot about under the stones play.

Speaking of which:

Click Here To Show Diagram Code

[go]$$B
$$ -------------------------------
$$ . . . . O . B B B . W . . . . .
$$ . . . X O O . O O O W . X . . .
$$ . . X . X O O X O X . X . . . .
$$ . . . . X X X X X X . . X . . .
$$ . . . . . . . . . . . . . . . .
$$ . . . . . . . . . . . . . . . .[/go]

Black made a mistake in the original problem and left behind this seki, right?

Hint:

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

But in terms of improving your play, those are the most important.

Ideally you are working on may types of problems at the same time. Ones hard enough to challenge your reading ability even though you are told the goal are good for building reading skills. Ones that are somewhat easier, that knowing the goal you can solve in the amount of time you could afford to spend in a game DO help your play in under some special situations*. But even easier ones that you can solve at that speed WITHOUT knowing the status (CAN that group be killed, CAN that group live even though the other player moves first -- and if so, live with points, live in seki, ko) are what will most improve your game.

Remember, as a practical matter, can be very important to correctly decide "is that move senti?"

* example -- a quick count shows that you will lose the game unless either one of the opponent's not quite safe yet groups can be killed --- then you can analyze based on "kill" because the alternative is "resign"

In relation to Bill's problem:

May be, but those cannot be often found in Go books.

Additionally, problems that ask for the status of a group can be clustered into
A) Black to live, Black to kill (colours reversed)
B) Black is alive
C) Black is dead

A) is by far the most interesting section for writing a book about tsume-go, concentrating especially on shape issues and vital points.

B) and C) can be left for life-and-death dictionaries, or for books that aim at showing the impact of life-and-death on practical play. Problems of this cluster are not really suitable for studying vital shape points, just because there is nothing that you can do (probably with the exception of looking for the best endgame sequence included).

In my book on one-move problems, I tried to "mirror" every problem (life <> death). However, this is not practical in every case. Sometimes "Black to kill" is too trivial as to be really valuable. More often, reaching either "life" (exclusive) or "death" needs more than one move, and so has to be kept in reserve for future usage.

(Basic) Shapes of the "zero-move" kind that are part of the B) / C) cluster are also explained in my book, for the sake of completeness.

_________________
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

With the hint it's rather easy, however I must have a very very good day if I would spot that in an actual game without "hint"

Click Here To Show Diagram Code

[go]$$Bcm5 Badumtsss
$$ -------------------------------
$$ . . . X O O . 1 . O O . . . . .
$$ . . . X O O . O O O O . X . . .
$$ . . X . X O O X O X . X . . . .
$$ . . . . X X X X X X . . X . . .
$$ . . . . . . . . . . . . . . . .
$$ . . . . . . . . . . . . . . . .[/go]

This is better. In both variations, White has exactly one ko threat. In this variation, if White plays a ko threat answered by Black, the white group retains less aji because Black can remove at a to better defend his left stones if necessary:

Click Here To Show Diagram Code

[go]$$Bcm5 less aji
$$ -------------------------------
$$ . . . X O O 3 1 2 O O . . . . .
$$ . . . X O O a O O O O . X . . .
$$ . . X . X O O X O X . X . . . .
$$ . . . . X X X X X X . . X . . .
$$ . . . . . . . . . . . . . . . .
$$ . . . . . . . . . . . . . . . .[/go]

Compare: more aji after ko threat:

Click Here To Show Diagram Code

[go]$$Bcm5 Badumtsss
$$ -------------------------------
$$ . . . X O O 1 3 . O O . . . . .
$$ . . . X O O 2 O O O O . X . . .
$$ . . X . X O O X O X . X . . . .
$$ . . . . X X X X X X . . X . . .
$$ . . . . . . . . . . . . . . . .
$$ . . . . . . . . . . . . . . . .[/go]

Here, Black does not have the extra option of fast defense for his left stones.

As I said, clarifying a chunk is hard!

An interesting shape

In our exploration of problem #222 we have encountered an interesting shape.

Click Here To Show Diagram Code

[go]$$Bcm7
$$ ---------------------
$$ | . . X . O O X X . .
$$ | O O 1 O . O O X . .
$$ | O X O O O X X X . .
$$ | X X X X X . . . . ,
$$ | . X . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .[/go]

kills in an interesting way. The two Black stones complete a shape known as Golden Cock Stands on One Leg. Its key characteristic is that the Black stones have two dame but that White cannot fill either without putting his own stones in atari. Experienced players are familiar with it from the following seki.

Click Here To Show Diagram Code

[go]$$B Seki
$$ -----------------------
$$ | . O . X . O O X X . .
$$ | O O O X O . O O X . .
$$ | O X O O X O O X X . .
$$ | X X X X X X X . . , .
$$ | . X . . . . . X . . .
$$ | . . . . . . . . . . .
$$ | . . . . . . . . . . .[/go]

If the solver was unaware of it, he could have learned it in the course of exploring the problem. In fact, it occurs in another variation.

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------
$$ | . 4 3 . 5 . . X . .
$$ | O O . 2 1 W W X . .
$$ | O X O O O X X X . .
$$ | X X X X X . . . . ,
$$ | . X . . . . . . . .
$$ | . . . . . . . . . .
$$ | . . . . . . . . . .[/go]

With the Golden Cock Stands on One Leg. and descend to the first line and have 2 dame neither of which White may fill without putting White stones in atari. White can still make life, but Black can then capture the stones.

Note that this shape is not about eyes, but about damezumari.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

They don't bring result because go is not chess. In Chess if you solve thousands of problems you can be very good because chess is very limited. In go, you can lose large groups of stones and still win the game with the right strategy.

I don't do much go problems, but focus on strategy and theory. Tsumego can't hurt, but only doing that is a mistake.

_________________
Stefany, web programmer

I agree that go is not chess, but I disagree that go problems do not bring results. The OP was not doing a lot of problems and there are go problems that teach strategy and theory as well.

I have had very good results recently with doing go problems, but I did a lot more than 10 per day and they were not tsumego, either, but problems like "choose A, B or C in this opening", "enclose this group or try to kill it?", "respond to this ko threat or not?", "where is the right endgame move against the upper right corner?".

Yes of course.... I think confused tsumego (life and death) with normal go problems.... You are right!

_________________
Stefany, web programmer