This 'n' that

Bill Spight · Post by **Bill Spight** » Wed Apr 20, 2016 12:53 pm

Now, at long last, the easy problem from Igo Tsumekata.

Click Here To Show Diagram Code: [go]$$W White to play and kill $$ ---------------- $$ . . . . . . . . | $$ . . O O X . . . | $$ . . O X . X . . | $$ . . O X , X X . | $$ . . . O . O O . | $$ . . . O . . . . | $$ . . . . . O . . | $$ . . . . . . . . | $$ . . . . . . . . |[/go]

The first play is kind of obvious.

Click Here To Show Diagram Code: [go]$$W White to play and kill $$ ---------------- $$ . . . . . . . . | $$ . . O O X 2 1 . | $$ . . O X . X . . | $$ . . O X 3 X X . | $$ . . . O . O O . | $$ . . . O . . . . | $$ . . . . . O . . | $$ . . . . . . . . | $$ . . . . . . . . |[/go]

If

,

leaves a dead shape in the corner, which is familiar to experienced players.

Click Here To Show Diagram Code: [go]$$W Dieter's hane $$ ---------------- $$ . . . 6 3 4 7 . | $$ . . O O X 5 1 . | $$ . . O X a X . . | $$ . . O X 2 X X . | $$ . . . O . O O . | $$ . . . O . . . . | $$ . . . . . O . . | $$ . . . . . . . . | $$ . . . . . . . . |[/go]

If

,

is Dieter's hane. Black can prevent the connection, but at the cost of the eye at "a". This is the line in the book.

----

Practical problems?

I like this problem because I think that it is practical. Not that it will occur as is in any game, but the idea is important and easy to grasp.

There is a school of thought that the best problems are the practical ones, those that come up in real games or are similar to positions that do. That is one reason that it is good to study your own games. The problems that they present are definitely practical.

But I also like the idea of thoroughly understanding positions in limited regions of play; like the 7 point corner in the first variation. Now, that position is a practical one to know. But what about this position?

Click Here To Show Diagram Code: [go]$$B Nim anyone? (Outer stones alive) $$ ------------------- $$ . . X O . . X O . . $$ . . X X X O O O . . $$ . . . . . . . . . .[/go]

There is a certain charm to the play on these four points. And yes, it is related to the game of Nim.

I was pleased to discover it a few years ago.

But that is the thing. I discovered it. I have never seen the like in a game, nor do I expect to. And even if it were to occur in a game, the chance that knowing how to play it would be crucial is miniscule. I do think that there is some practical value in seeing the under the stones possibilities, though.

EdLee · Post by **EdLee** » Wed Apr 20, 2016 11:50 pm

Hi Bill, Thanks for posting these.

Bill Spight · Post by **Bill Spight** » Fri Apr 22, 2016 9:37 am

I think that Igo Tsumekata ( http://dl.ndl.go.jp/info:ndljp/pid/861034/36 ) has a lot of practical problems, most of them at the kyu level. However, to read the answers in the text it helps to know the Chinese numerals.

With that caveat I can recommend the book.

Here is an easy one. And practical, I think.

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

Enjoy!

EdLee · Post by **EdLee** » Fri Apr 22, 2016 9:49 am

EdLee · Post by **EdLee** » Fri Apr 22, 2016 11:15 am

Bill Spight wrote:to read the answers in the text it helps to know the Chinese numerals.

Hi Bill,

The Arabic numerals were an excellent invention.

Do you happen to know when this book was originally published ?

Very practical -- Thanks.

Bill Spight · Post by **Bill Spight** » Fri Apr 22, 2016 12:42 pm

EdLee wrote:Do you happen to know when this book was originally published ?

It was part of a set published in 1901. The father died in 1893. I don't know if there was an earlier edition.

jeromie · Post by **jeromie** » Fri Apr 22, 2016 1:47 pm

Without peeking at Ed's answer, here's my solution. That's a nice problem!

Bill Spight · Post by **Bill Spight** » Fri Apr 22, 2016 10:19 pm

Here is a problem that appears in several sources.

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

For background, say that Black invades the top left White corner. :w10:

plays a two step hane.

Click Here To Show Diagram Code: [go]$$Bm11 Black invasion, II $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . X O O . . . . . . . . . . . . . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | 1 X O . . . . . . . . . . . . . . . . | $$ | . O 2 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

descends to the first line, and :w12:

connects.

Suppose that Black now tenukis. That yields the problem position. Modern versions strengthen White on the left side, to keep Black contained. Let's do that for the problem diagram.

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

White to play in the top left corner, with what result?

Enjoy!

EdLee · Post by **EdLee** » Fri Apr 22, 2016 11:45 pm

Bill Spight wrote:It was part of a set published in 1901. The father died in 1893.

Hi Bill,

Just curious: how did you come across this set (and the website) ?
I see a Mr. Kobayashi (?) and his son(?); was he/were they pro ?
Or Honinbo or other title holders ?

EdLee · Post by **EdLee** » Sat Apr 23, 2016 12:18 am

Bill Spight · Post by **Bill Spight** » Sat Apr 23, 2016 1:15 am

EdLee wrote:
Bill Spight wrote:It was part of a set published in 1901. The father died in 1893.
Hi Bill,

Just curious: how did you come across this set (and the website) ?
I see a Mr. Kobayashi (?) and his son(?); was he/were they pro ?
Or Honinbo or other title holders ?

I stumbled across the Japanese National Library site some years ago. I found this set by doing a search there for tsumego. The father was a 7 dan (awarded posthumously, I think); the son was a shodan. They have pages on SL. ( http://senseis.xmp.net/?KobayashiTetsujiro , http://senseis.xmp.net/?KobayashiKentaro )

Bill Spight · Post by **Bill Spight** » Wed Apr 27, 2016 7:57 am

A cook?

Here is the answer in Igo tsumekata to the easy problem.

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

It is, in fact, the only line of play shown in the text. Occasionally it shows a variation or two on the main line, but usually not. That has good and bad aspects.

Both of our solvers started with :b1:

at 2. Was that a mistake, or was the problem cooked? The text is no help. (BTW, my impression is that cooks were not considered to be flaws in ancient problems. It is not unusual for go positions to have more than one correct line of play which transpose into the same result.)

With no failure diagrams or variations, the reader could, and, IMO, usually should, explore those possibilities. In particular, if a play is correct there should be an answer to every reply, not just the one in the main line.

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

If

, this rollup is familiar to experienced players.

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

fills at 5.

If :w2:

, this rollup may be somewhat less familiar.

Click Here To Show Diagram Code: [go]$$ Solution 2? $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . , . . . . . , . . . . X , O . . | $$ | . . . . . . . . . . . . X . X O . . . | $$ | . . . . . . . . . . . X . W W X X X 3 | $$ | . . . . . . . . . . . . . W X O O O . | $$ | . . . . . . . . . . . . X 5 X X O 4 . | $$ | . . . . . . . . . . . . . . . X 1 2 . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This is the solution given by Ed and jeromie. In this variation :b3:

threatens the rollup in variation 2. :w4:

defends against that, and the :b5:

wins the capture fight.

At first glance not only is the problem cooked, but this is a better solution than the one in the book. Why was that the answer given? Was it an oversight by the son, who was probably weaker than today's pros? Or is there some other reason?

Can the marked stones escape in this variation, because of Black's shortage of liberties after :b1:

-

? Or can White exploit that shortage in some other way? These questions go beyond the scope of this position as a tsumego problem per se, but they are practical questions.

jeromie · Post by **jeromie** » Wed Apr 27, 2016 10:41 am

I've been meaning to answer this one for a while. Still haven't peeked at Ed's answer. :-)

Thought it might be fun to share my kyu-level thought process on this one. The first move I think of is the hane at 1. But I know the comb formation is alive, so when black descends with 2 he will live.

Click Here To Show Diagram Code: [go]$$W The comb formation is alive $$ --------------------------------------- $$ | . 1 . . . . . . . . . . . . . . . . . | $$ | 2 X O O . . . . . . . . . . . . . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | X X O . . . . . . . . . . . . . . . . | $$ | . O O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

So then I look for an interior play. The first thing I'll check is this move, since it's the most common attack against the comb formation. My only concern is that this is close enough to the corner that I have to worry about black getting an eye by playing at my initial 1 above.

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

If black plays immediately at the 2-1, 3 captures some black stones because of a shortage of liberties.:

Click Here To Show Diagram Code: [go]$$W Black can't play at a or b $$ --------------------------------------- $$ | . 2 . . . . . . . . . . . . . . . . . | $$ | . X O O . . . . . . . . . . . . . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | 1 a X O . . . . . , . . . . . , . . . | $$ | b 3 X O . . . . . . . . . . . . . . . | $$ | X X O . . . . . . . . . . . . . . . . | $$ | . O O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

So maybe black tries this. But the same shortage of liberties problem shows up:

Click Here To Show Diagram Code: [go]$$W Black can't play at a or b $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . X O O . . . . . . . . . . . . . . . | $$ | 2 . X O . . . . . . . . . . . . . . . | $$ | 1 b X O . . . . . , . . . . . , . . . | $$ | a 3 X O . . . . . . . . . . . . . . . | $$ | X X O . . . . . . . . . . . . . . . . | $$ | . O O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

So let's go with the normal defense if the comb shape was completed:

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

I still think there's something weird with the corner, so let's try a different defense for black. With this 4, the outside descent doesn't work. If white plays a to make a dead 3 shape, black captures at b and gets two eyes at 1 or c.

Click Here To Show Diagram Code: [go]$$W Black lives $$ --------------------------------------- $$ | . c . . . . . . . . . . . . . . . . . | $$ | 6 X O O . . . . . . . . . . . . . . . | $$ | 3 4 X O . . . . . . . . . . . . . . . | $$ | 1 2 X O . . . . . , . . . . . , . . . | $$ | a b X O . . . . . . . . . . . . . . . | $$ | X X O . . . . . . . . . . . . . . . . | $$ | 5 O O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

So let's try a different 5. This still doesn't seem to work for white, but now I'm looking for a possible ko in the corner.

Click Here To Show Diagram Code: [go]$$W Black still lives $$ --------------------------------------- $$ | . 5 . . . . . . . . . . . . . . . . . | $$ | 7 X O O . . . . . . . . . . . . . . . | $$ | 3 4 X O . . . . . . . . . . . . . . . | $$ | 1 2 X O . . . . . , . . . . . , . . . | $$ | 6 . X O . . . . . . . . . . . . . . . | $$ | X X O . . . . . . . . . . . . . . . . | $$ | . O O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

This 5 ends up in the same position as above.

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

So I think black lives if white plays the normal attack on the comb formation. Is there a better attack for white? a-d all look like interesting points. I won't show an exhaustive thought process for these. :-)

Click Here To Show Diagram Code: [go]$$W $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | d X O O . . . . . . . . . . . . . . . | $$ | . b X O . . . . . . . . . . . . . . . | $$ | . a X O . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | X X O . . . . . . . . . . . . . . . . | $$ | c O O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . |[/go]

I looked at all of a-d, but I'll just show what I think is the best solution. If white plays at d, I find the ko I was looking for. White has to find the first ko threat, but I think this is best:

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

jeromie · Post by **jeromie** » Wed Apr 27, 2016 10:53 am

@Ed:

Bill Spight · Post by **Bill Spight** » Thu Apr 28, 2016 9:01 am

Kudos to jeromie for his work on the latest problem. :clap:

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

Here is the main line, hidden in case anyone wants to still work on it.

Life In 19x19

This 'n' that

Re: This 'n' that

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