Unsolvable tsumegos in Cho's elementary book? - Help needed

[Novbert]

Hi All,

I've just started to play go recently and I've started to go through Cho Chikun's Elementary Encyclopedia of Life and Death but I've found some problems which doesn't look solvable.
Any help would be appreciated.

Supposedly all of them should be solved by black playing first, but Problem 81 looks like this:

(;GM[1]FF[4]CA[UTF-8]SZ[19]AW[bb][bc][cc][dc][ed][fc][gc][hc][hb]AB[ca][cb][db][ec][fb][gb][ga](;B[ea];W[eb];B[ba];W[ec])(;B[eb];W[ea]))

As I see neither '1' nor '2' helps black - '1' leaves him with two false eyes, while '2' leads to only a single real one.
Am I missing something or is there an error here?

The other one is a bit more tricky (problem #97 in the same book):

(;GM[1]FF[4]CA[UTF-8]SZ[19]AB[bb][cc][cd][ce][de][ee][fe][gd][gc][gb][fb][da]AW[cb][bc][dc][dd][ed][fd][fc][eb][ea]TR[bc]LB[db:A](;B[ca];W[db](;B[ba];W[ab];B[bd];W[aa])(;B[ab])(;B[fa];W[ba];B[ca];W[ab]))(;B[ba](;W[ab];B[bd];W[db];B[ac];W[ca])(;W[db];B[ca];W[ab];B[fa];W[aa])))

Black has to play at '1' or '2' to prevent white from playing at '1' immediately. In any of those cases White can play at 'A', giving atari in both cases. Eventually black can't survive in the corner (mostly due to that marked white stone), so can't kill white.
The question is the same: Is this tsumego really flawed or am I missing something?

[HermanHiddema]

In the first one, option 1 makes ko.

In the second one, you need to play 1-1 at move 3

[Novbert]

HermanHiddema: Thank you! It really works

[Uberdude]

I've just started to play go recently ...

The question is the same: Is this tsumego really flawed or am I missing something?

I think it's more likely to be the later, than Cho Chikin 9 dan pro made a mistake.

[tchan001]

I've just started to play go recently ...

The question is the same: Is this tsumego really flawed or am I missing something?

I think it's more likely to be the later, than Cho Chikin 9 dan pro made a mistake.

Take a look at Cho's intermediate problem #344 and let us know what you think

$$Bc
$$ +---------------------------
$$ | . . . . . . . . . . . . .
$$ | . O . O X X O O . . . . .
$$ | . X . X X O X X O . . . .
$$ | . O X X O O . . O , . . .
$$ | . O O O . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------
$$ | . . . . . . . . . . . . .
$$ | . O . O X X O O . . . . .
$$ | . X . X X O X X O . . . .
$$ | . O X X O O . . O , . . .
$$ | . O O O . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .
$$ | . . . . . . . . . . . . .[/go]

[Novbert]

I've just started to play go recently ...

The question is the same: Is this tsumego really flawed or am I missing something?

I think it's more likely to be the later, than Cho Chikin 9 dan pro made a mistake.

Good point, but the pdf files I'm using were generated from Cho problems and went through a lot of transformation - so I though that maybe that process was the source of the issue. Good to know it's not the case.

[illluck]

@tchan: Note the use of "more likely", there's no claim of infallibility.

[Joaz Banbeck]

If we can't even spell his name correctly, I doubt we're going to catch him in a mistake.

[Uberdude]

If we can't even spell his name correctly, I doubt we're going to catch him in a mistake.

Darn iPhone keyboard!

[tchan001]

If we can't even spell his name correctly, I doubt we're going to catch him in a mistake.

Actually we have in caught a mistake in an old GD thread which I made into an sgf for myself earlier. Enjoy Advanced prob #36

(;GM[1]FF[4]SZ[19]HA[0]KM[0]GN[Cho L&D (abc)]AB[ba][bb][cb][db][cc][hc][ic][ad][bd][cd][dd][ed][ie]AW[ca][da][ab][eb][ac][dc][ec][gc][gd][ge][bf][cf][ef][gf]C[Advanced]
(;B[gb]WV[];W[fa]
(;B[fc]
;W[fb]C[Wrong.])
(;B[fb];W[fc];B[ea]
;W[da]C[Wrong.])
(;B[ea]
;W[da]C[Wrong.]))
(;B[ea]WV[];W[da]C[Wrong.])
(;B[fb]WV[];W[fc];B[ea]
;W[da]C[Wrong.])
(;B[fc];W[fb];B[gb]
(;W[fd]C[Original line]
(;B[fa];W[hb];B[ea];W[ga]
;B[da]C[Correct.])
(;B[ea]WV[];W[da]C[Wrong.]))
(;W[fa]C[Move posed by sol.ch (Godiscussions.com) which seems to make the problem unsolvable.])))

Answer in sgf form hidden if you don't want to see it

(;GM[1]FF[4]SZ[19]HA[0]KM[0]GN[Cho L&D (abc)]AB[ba][bb][cb][db][cc][hc][ic][ad][bd][cd][dd][ed][ie]AW[ca][da][ab][eb][ac][dc][ec][gc][gd][ge][bf][cf][ef][gf]C[Advanced]
(;B[gb]WV[];W[fa]
(;B[fc]
;W[fb]C[Wrong.])
(;B[fb];W[fc];B[ea]
;W[da]C[Wrong.])
(;B[ea]
;W[da]C[Wrong.]))
(;B[ea]WV[];W[da]C[Wrong.])
(;B[fb]WV[];W[fc];B[ea]
;W[da]C[Wrong.])
(;B[fc];W[fb];B[gb]
(;W[fd]C[Original line]
(;B[fa];W[hb];B[ea];W[ga]
;B[da]C[Correct.])
(;B[ea]WV[];W[da]C[Wrong.]))
(;W[fa]C[Move posed by sol.ch (Godiscussions.com) which seems to make the problem unsolvable.])))

[MoxElliot]

I love this problem collection. I also love to have a big problem rescourse without solutions.

What are the possible outcomes? Are they all black to play and live/kill? Do kos count as a win? How about black to escape or seki?

Thanks!

[Abyssinica]

Some problems will have ko for an answer and some will have seki. I've come across a few where the choice is between ko and seki. If you get a ko, see if you can get better. If you get a seki, see if you can get better. If you can't, then oh well, you can't have a perfect life everytime.

[leichtloeslich]

As it says in the beginning, it's always black to move first.
For further info see here -> http://senseis.xmp.net/?TsumegoConventions <-
Order is life or ko if you're defending and death or ko if you're attacking.

In a tsumego you don't care about whether you get points or you live in seki. It's both unconditional life and considered better than ko.

As for the topic of this thread, here a few more examples of unsolvable tsumegos from that collection:

elementary #218:

$$B
$$ +------------------
$$ | . O . O . X . . .
$$ | X . X . X O . O .
$$ | O X X X O O . . .
$$ | . O . O O . . . .
$$ | . . O . . . . . .
$$ | . O . . . . . . .
$$ | . . . . . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ +------------------
$$ | . O . O . X . . .
$$ | X . X . X O . O .
$$ | O X X X O O . . .
$$ | . O . O O . . . .
$$ | . . O . . . . . .
$$ | . O . . . . . . .
$$ | . . . . . . . . .[/go]

elementary #533:

$$B
$$ +----------------
$$ | . O . . O O . .
$$ | . . X O X O . .
$$ | . X X X X O . .
$$ | O O O O O O . .
$$ | . . . . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ +----------------
$$ | . O . . O O . .
$$ | . . X O X O . .
$$ | . X X X X O . .
$$ | O O O O O O . .
$$ | . . . . . . . .[/go]

and advanced #31:

$$B
$$ +------------------
$$ | . O . X O . . . .
$$ | X X X X X O . O .
$$ | O O O O X O . . .
$$ | . . . , X O . . .
$$ | . O O X X O . . .
$$ | . X X . . O . . .
$$ | . O O O O . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .
$$ | . . . , . . . . .

Click Here To Show Diagram Code

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

this last one in particular I found in another problem collection and the problem is simply missing stones on the outside. The problem should be

$$B
$$ +------------------
$$ | . O . X O . . . .
$$ | X X X X X O . O .
$$ | O O O O X O . . .
$$ | . . . , X O . . .
$$ | . O O X X O . . .
$$ | . X X . . O . . .
$$ | . O O O O . . . .
$$ | . . . . . . . . .
$$ | . X . X . . . . .
$$ | . . . , . . . . .

Click Here To Show Diagram Code

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

[Abyssinica]

Thanks for telling me which ones are unsolvable, because they just happen to be the two (I felt bad for skipping 533) I could never solve and always wondered about. That and the occasional other kyu in the kgs teaching ladder.