A "Pro-Level" Tsumego

hiyayang · Post by **hiyayang** » Tue Dec 28, 2010 3:28 pm

Flipping through my past issues of Weiqi Tiandi ("Go World" in China, unrelated to the American one), I noticed the following tsumego problem (2006.15). It says that if you can solve it within 10 minutes, your fundamental skills have reached the pro level. That gave me a chuckle or two, because it took me only a few seconds to arrive at the solution. (Hohoho, I am a pro :lol:

)

Seriously, I think the editor way over-estimated the difficult level of the problem. Give it a try and let me know what you think.

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | . O X O . O . . . . . . . . . . . . . | $$ | . . O O . O X . . , . . . . . , . . . | $$ | . . . O X X . X . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . X . O . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Loons · Post by **Loons** » Tue Dec 28, 2010 4:11 pm

Just shooting in the dark, I would try this-

cyclops · Post by **cyclops** » Wed Dec 29, 2010 3:48 am

I had the same intuition. But then I realised

So B needs to accept ko?

CSamurai · Post by **CSamurai** » Wed Dec 29, 2010 4:03 am

cyclops wrote:I had the same intuition. But then I realised
W next forces a ko at a3/a4 and lives in ko. So I tried B3 at a5 but that doesn't work because W4 at a2.
So B needs to accept ko?

You're seeing spoons.

There is no ko.

Bigstrongpolarbear · Post by **Bigstrongpolarbear** » Wed Dec 29, 2010 4:11 am

What if white throws in at b2 instead?

CSamurai · Post by **CSamurai** » Wed Dec 29, 2010 4:22 am

Bigstrongpolarbear wrote:What if white throws in at b2 instead?

Not sure, but it doesn't seem to go anywhere.

After the capture at c2, white is left trying to force seki, and lacking enough places to play at once.

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 7 O X O . O . . . . . . . . . . . . . | $$ | . 2 O O . O X . . , . . . . . , . . . | $$ | 6 1 . O X X . X . . . . . . . . . . . | $$ | 3 4 5 O X . . . . . . . . . . . . . . | $$ | . X 8 O . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

9 is at 4, and white lacks life. If they don't play 8 to try to force some sort of seki, then black can force a rabbity six, eventually.

At least, that's my flawed read.

I just don't see any kos here.

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 7 O X O . O . . . . . . . . . . . . . | $$ | . 2 O O . O X . . , . . . . . , . . . | $$ | 6 1 8 O X X . X . . . . . . . . . . . | $$ | 3 4 5 O X . . . . . . . . . . . . . . | $$ | . X . O . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

black hapily plays 9 at 4, and thanks white for killing themselves.

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . B . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | 0 X X X . . . X . . . . . . . . . . . | $$ | 7 O X O . O . . . . . . . . . . . . . | $$ | 8 2 O O . O X . . , . . . . . , . . . | $$ | 6 1 9 O X X . X . . . . . . . . . . . | $$ | 3 4 5 O X . . . . . . . . . . . . . . | $$ | . X . O . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

marked black stone prevents white from threatening to escape and crawl along the second line.

Not sure what else white could try..

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . 9 . . . X . . . . . . . . . . . . . | $$ | 8 X X X . . . X . . . . . . . . . . . | $$ | 6 O X O . O . . . . . . . . . . . . . | $$ | . 2 O O . O X . . , . . . . . , . . . | $$ | 7 1 . O X X . X . . . . . . . . . . . | $$ | 3 4 5 O X . . . . . . . . . . . . . . | $$ | . X . O . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Not elegant, but blocked..

Not sure what your throw in is aiming at. Maybe I'm missing something?

Edit: one error..

Click Here To Show Diagram Code: [go]$$Bc Black to play $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . B . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | 0 X X X . . . X . . . . . . . . . . . | $$ | 7 O X O . O . . . . . . . . . . . . . | $$ | 8 2 O O . O X . . , . . . . . , . . . | $$ | 6 1 9 O X X . X . . . . . . . . . . . | $$ | 3 4 5 O X . . . . . . . . . . . . . . | $$ | . X . O . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Black doesn't actually need nine, as he can play it any time.

So he should seal at 0 instead, and remove the ko threat in case the game develops that way later.

Bigstrongpolarbear · Post by **Bigstrongpolarbear** » Wed Dec 29, 2010 5:57 am

You're right, I was just hallucinating something that could never possibly work.

cyclops · Post by **cyclops** » Thu Dec 30, 2010 7:12 am

Bigstrongpolarbear wrote:You're right, I was just hallucinating something that could never possibly work.

Also caught by a Samurai spoon. :lol:

hiyayang · Post by **hiyayang** » Fri Dec 31, 2010 7:12 pm

Looks like you all got it right! Here is the solution given in the magazine:

Two bonus questions: Assuming the tsumego position was reached this way:

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | . O X O . O . . . . . . . . . . . . . | $$ | . . O O . O X . . , . . . . . , . . . | $$ | . . . O X X . X . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . 1 . 2 . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

1. Can

do better?

2. Can :b1:

do better?

gonut · Post by **gonut** » Sat Jan 01, 2011 4:02 pm

Black's 1st move may not have been correct, so White seems able to take the vital point to live.

However, improving on Black's 1st move seems to be beyond my pay grade.

ethanb · Post by **ethanb** » Sat Jan 01, 2011 4:26 pm

Click Here To Show Diagram Code: [go]$$Bc Black to kill $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 1 O X O . O . . . . . . . . . . . . . | $$ | . . O O . O X . . , . . . . . , . . . | $$ | . . . O X X . X . . . . . . . . . . . | $$ | . 2 . O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Looks like this white lives, but black has lots of sente endgame. I'd be ok in most real games with this if I couldn't find the kill.

Click Here To Show Diagram Code: [go]$$Bc Black to kill $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 5 O X O . O . . . . . . . . . . . . . | $$ | 8 9 O O . O X . . , . . . . . , . . . | $$ | . 2 . O X X . X . . . . . . . . . . . | $$ | 6 1 3 O X . . . . . . . . . . . . . . | $$ | . 7 . 4 . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This one seems to be a ko. Better, but unfortunately I'm taking a quick break from work... so since I didn't see it the first two times, I'm saying it's ko.

hiyayang · Post by **hiyayang** » Sun Jan 02, 2011 12:02 pm

Here is my take on the bonus questions:

I suspect the first move is the same in all three questions: B3 is the vital point for both black and white.

Click Here To Show Diagram Code: [go]$$Wc white lives $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | b O X O . O . . . . . . . . . . . . . | $$ | . . O O . O X . . , . . . . . , . . . | $$ | . 1 . O X X . X . . . . . . . . . . . | $$ | . a 2 O X . . . . . . . . . . . . . . | $$ | . X . 3 . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

seems the strongest resistance by black -- If white got this spot (and a solid eye at C3), it seems so easy for white to live.

Still, after :w3:

, 'a' and 'b' are miai for white to live.

Regarding the last question, seki is a possibility:

Click Here To Show Diagram Code: [go]$$Bc seki $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | a X X X . . . X . . . . . . . . . . . | $$ | 7 O X O . O . . . . . . . . . . . . . | $$ | 8 2 O O . O X . . , . . . . . , . . . | $$ | . 1 . O X X . X . . . . . . . . . . . | $$ | 6 5 4 O X . . . . . . . . . . . . . . | $$ | . 3 . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

but I am not sure whether it is the best. A similar shape is given in the section on Carpenter's Squares in Segoe Kensaku's Tsumego Dictionary (http://senseis.xmp.net/?SegoeTsumegoDictionary), where black kills the white corner. The key difference between the two shapes is that the white group here has quite a few outside liberties.

Point wise, the seki is no better (and possibily even worse, because of white's endgame move at 'a') for black than simply letting white live like this:

Click Here To Show Diagram Code: [go]$$Bc plain and simple $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 3 O X O . O . . . . . . . . . . . . . | $$ | . 1 O O . O X . . , . . . . . , . . . | $$ | . 2 . O X X . X . . . . . . . . . . . | $$ | . 4 . O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Of course, white may opt for a ko fight instead of seki:

Click Here To Show Diagram Code: [go]$$Bc ko $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 6 O X O . O . . . . . . . . . . . . . | $$ | . 2 O O . O X . . , . . . . . , . . . | $$ | 8 1 . O X X . X . . . . . . . . . . . | $$ | 7 5 4 O X . . . . . . . . . . . . . . | $$ | . 3 . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

If black resists the ko fight, white just has enough outside liberties to make the kill:

Click Here To Show Diagram Code: [go]$$Bc white lives $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | 3 X X X 9 5 . X . . . . . . . . . . . | $$ | O O X O 8 O 7 . . . . . . . . . . . . | $$ | 6 O O O . O X . . , . . . . . , . . . | $$ | 1 X 0 O X X . X . . . . . . . . . . . | $$ | 2 X O O X . . . . . . . . . . . . . . | $$ | . X 4 . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

To avoid the ko fight (and force the seki), black should hane first, playing :b5:

before

in this diagram:

Click Here To Show Diagram Code: [go]$$Bc seki, no ko $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 5 O X O . O . . . . . . . . . . . . . | $$ | 6 2 O O . O X . . , . . . . . , . . . | $$ | . 1 . O X X . X . . . . . . . . . . . | $$ | 8 7 4 O X . . . . . . . . . . . . . . | $$ | . 3 . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

It doesn't change anything if white switches the order of :w6:

and

.

To force a ko fight, black would have to play 2-2 as the first move:

Click Here To Show Diagram Code: [go]$$Bc ko $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 5 O X O . O . . . . . . . . . . . . . | $$ | 7 8 O O . O X . . , . . . . . , . . . | $$ | . 2 . O X X . X . . . . . . . . . . . | $$ | 6 1 3 O X . . . . . . . . . . . . . . | $$ | . 0 9 4 . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Black can still change his mind at the last minute to get a seki instead:

Click Here To Show Diagram Code: [go]$$Bc seki $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 5 O X O . O . . . . . . . . . . . . . | $$ | 7 8 O O . O X . . , . . . . . , . . . | $$ | . 2 . O X X . X . . . . . . . . . . . | $$ | 6 1 3 O X . . . . . . . . . . . . . . | $$ | . 9 0 4 . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

that is, unless white forces the ko:

Click Here To Show Diagram Code: [go]$$Bc ko $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 5 O X O . O . . . . . . . . . . . . . | $$ | 7 . O O . O X . . , . . . . . , . . . | $$ | 9 2 . O X X . X . . . . . . . . . . . | $$ | 6 1 3 O X . . . . . . . . . . . . . . | $$ | . 8 0 4 . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

If a ko fight is unavoidable, white might be better off fight it this way:

Click Here To Show Diagram Code: [go]$$Bc ko $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 5 O X O . O . . . . . . . . . . . . . | $$ | 6 . O O . O X . . , . . . . . , . . . | $$ | . 2 . O X X . X . . . . . . . . . . . | $$ | . 1 3 O X . . . . . . . . . . . . . . | $$ | . . . 4 . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In standard carpenter's square, white's correct response to :b1:

is

in the diagram below, which might as well be the best defense for white here, if a ko fight is unfavorable to white.

Click Here To Show Diagram Code: [go]$$Bc best defense? $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | a O X O . O . . . . . . . . . . . . . | $$ | . . O O . O X . . , . . . . . , . . . | $$ | . b . O X X . X . . . . . . . . . . . | $$ | . 1 c O X . . . . . . . . . . . . . . | $$ | . 2 . d . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Black's next move can be a, b, c or d, but in each case it appears that the result would be seki or ten-thousand year ko.

usagi · Post by **usagi** » Sun Jan 02, 2011 9:18 pm

hiyayang wrote:Flipping through my past issues of Weiqi Tiandi ("Go World" in China, unrelated to the American one), I noticed the following tsumego problem (2006.15). It says that if you can solve it within 10 minutes, your fundamental skills have reached the pro level. That gave me a chuckle or two, because it took me only a few seconds to arrive at the solution. (Hohoho, I am a pro )

Seriously, I think the editor way over-estimated the difficult level of the problem. Give it a try and let me know what you think.

Hello!

Back when Willzhang was teaching on KGS, I was his student, and he presented this problem to me. I, too, thought I found the solution in about 5-10 minutes. Then a few hours later, I thought I found the solution again. Then a day later. Eventually I gave up - he never told me the solution. I hope you have an answer book on hand because it's likely not what you think

CSamurai · Post by **CSamurai** » Sun Jan 02, 2011 11:45 pm

usagi wrote:
hiyayang wrote:Flipping through my past issues of Weiqi Tiandi ("Go World" in China, unrelated to the American one), I noticed the following tsumego problem (2006.15). It says that if you can solve it within 10 minutes, your fundamental skills have reached the pro level. That gave me a chuckle or two, because it took me only a few seconds to arrive at the solution. (Hohoho, I am a pro )

Seriously, I think the editor way over-estimated the difficult level of the problem. Give it a try and let me know what you think.

Hello!

Back when Willzhang was teaching on KGS, I was his student, and he presented this problem to me. I, too, thought I found the solution in about 5-10 minutes. Then a few hours later, I thought I found the solution again. Then a day later. Eventually I gave up - he never told me the solution. I hope you have an answer book on hand because it's likely not what you think

If you read carefully, you'll find that the poster has already shared the solution found in the article which he found the problem in.

hiyayang · Post by **hiyayang** » Wed Jan 05, 2011 10:39 am

@ethanb:

ethanb wrote:
$$Bc
$$ ---------------------------------------
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . . . X . . . . . . . . . . . |
$$ | 1 O X O . O . . . . . . . . . . . . . |
$$ | . . O O . O X . . , . . . . . , . . . |
$$ | . . . O X X . X . . . . . . . . . . . |
$$ | . 2 . O X . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------

Click Here To Show Diagram Code
[go]$$Bc $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 1 O X O . O . . . . . . . . . . . . . | $$ | . . O O . O X . . , . . . . . , . . . | $$ | . . . O X X . X . . . . . . . . . . . | $$ | . 2 . O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Looks like this white lives, but black has lots of sente endgame. I'd be ok in most real games with this if I couldn't find the kill.

How does white respond to this black move:

Click Here To Show Diagram Code: [go]$$Bc $$ --------------------------------------- $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . X . . . . . . . . . . . . . | $$ | . X X X . . . X . . . . . . . . . . . | $$ | 1 O X O . O . . . . . . . . . . . . . | $$ | . . O O . O X . . , . . . . . , . . . | $$ | . . . O X X . X . . . . . . . . . . . | $$ | 3 2 . O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Life In 19x19

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Re: A "Pro-Level" Tsumego

Re: A "Pro-Level" Tsumego

Re: A "Pro-Level" Tsumego

Re: A "Pro-Level" Tsumego

Re: A "Pro-Level" Tsumego

Re: A "Pro-Level" Tsumego

Re: A "Pro-Level" Tsumego

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Re: A "Pro-Level" Tsumego

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Re: A "Pro-Level" Tsumego

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