This 'n' that

Bill Spight · **#181**

Dear Friends,

I am going through a difficult time now, which is why I have not been posting much. Thanks to people for their interesting comments.

Let me briefly say something about Dieter's suggestion now, and comment more fully later.

Click Here To Show Diagram Code: [go]$$B Dieter's suggestion $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . a O 1 | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . |[/go]

Dieter is right that :b1:

is better than "a", Sakata's play, on average. That is:

Click Here To Show Diagram Code: [go]$$B No sacrifice $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O 1 | $$ . . . . . O O . 2 3 | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . |[/go]

This connection is better than the one in the book.

Click Here To Show Diagram Code: [go]$$B Sacrifice $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . 1 O 3 | $$ . . . . . O O 2 4 5 | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . |[/go]

On average it is 2 points better, which means that the book play is a serious flaw. A kyu level mistake, if you will.

Kudos to Dieter! :bow:

However, let us compare the two plays with a difference game.

Click Here To Show Diagram Code: [go]$$B Difference game $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O B | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X . . . | $$ . . . . . . . W X . | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

Who wins the difference game, playing first?

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

, capturing :wc:

, clearly wins the difference game.

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

If White tries to capture the :bc:

stone, Black throws in at 5 and connects by capturing two White stones. :w8:

at

would be connect-and-die.

Click Here To Show Diagram Code: [go]$$W White first $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . 2 O B | $$ . . . . . O O 3 4 . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X 1 . . | $$ . . . . . . . W X . | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

makes a large capture, and wins. Does this mean that sometimes :wc:

is correct?

Shaddy · **#182**

The result is strange because that's the wrong difference game. This should be the right one:

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

Bill Spight · **#183**

Shaddy wrote:

The result is strange because that's the wrong difference game. This should be the right one:

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

This is a transposition of the first Black first variation in the difference game above. Yes, Black to play wins the difference game. The question is whether White first also wins.

But you are on the right track about whether the above difference game is the right one.

Jhyn · **#184**

Bill Spight wrote:

Click Here To Show Diagram Code: [go]$$W White first $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . 2 O B | $$ . . . . . O O 3 4 . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X 1 . . | $$ . . . . . . . W X . | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

makes a large capture, and wins. Does this mean that sometimes :wc:

is correct?

I might be wrong about the purpose of a difference game, and this seems like the perfect example to clarify it.
There is a time where :wc:

can be obviously better, and that is as a ko threat. Furthermore your above diagram seems to illustrate this, i.e. :wc:

has the biggest follow-up after a tenuki. Do you think this could be the explanation?

Bill Spight · **#185**

Jhyn wrote:

Bill Spight wrote:

Click Here To Show Diagram Code: [go]$$W White first $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . 2 O B | $$ . . . . . O O 3 4 . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X 1 . . | $$ . . . . . . . W X . | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

makes a large capture, and wins. Does this mean that sometimes :wc:

is correct?

I might be wrong about the purpose of a difference game, and this seems like the perfect example to clarify it.
There is a time where :wc:

can be obviously better, and that is as a ko threat. Furthermore your above diagram seems to illustrate this, i.e. :wc:

has the biggest follow-up after a tenuki. Do you think this could be the explanation?

Difference games rely upon the independence of the two regions of the board being compared. Kos may destroy that independence. You are right that one line of play may be better than the other because of ko threats, but that is not something that difference games address. If this is the correct difference game to compare the two plays, then sometimes :wc:

(the book play) will be better than the first line cut, even if there are no kos or ko threats involved. The large follow-up after tenuki is the reason.

The caveat about kos means that difference games do not say absolutely that one play is better than another, but they give stronger evidence than the size of plays.

Jhyn · **#186**

Bill Spight wrote:

Difference games rely upon the independence of the two regions of the board being compared. Kos may destroy that independence. You are right that one line of play may be better than the other because of ko threats, but that is not something that difference games address. If this is the correct difference game to compare the two plays, then sometimes :wc:

(the book play) will be better than the first line cut, even if there are no kos or ko threats involved. The large follow-up after tenuki is the reason.

The caveat about kos means that difference games do not say absolutely that one play is better than another, but they give stronger evidence than the size of plays.

I understand that ko cannot be taken fully into consideration because of the possible dependence between the two regions. Still, consider that :wc:

would be sente in normal circumstances: if Black cuts, then in the absence of follow-up, this is a beneficial exchange for Black. If White goes first in the difference game, it means that the move was played as a gote, which I think doesn't make sense outside of an ongoing ko somewhere else on the board.

To reiterate my point: I believe that if Sakata's move is better, then this can only happen in the case that some ko is involved. I would love to be proven wrong.

Bill Spight · **#187**

Jhyn wrote:

To reiterate my point: I believe that if Sakata's move is better, then this can only happen in the case that some ko is involved. I would love to be proven wrong.

IMO, you are right. But that means that the above difference game is the wrong one to compare the two moves.

Bill Spight · **#188**

Shaddy is right that we are comparing the wrong difference game, and jhyn is right that the 3d line cut could be used as a ko threat. Remember that difference games and kos don't mix.

So what is the right difference game and why? How can we tell?

Click Here To Show Diagram Code: [go]$$B Correct difference game $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O B | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B . . | $$ . . . . . . . W X W | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

This is the correct difference game because

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

-

is a reverse which we can, and should for the purpose of the difference game, consider as a unit. OC, :b2:

prevents White from playing there to win the difference game. Let's play the game out.

Click Here To Show Diagram Code: [go]$$B Black first $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O B | $$ . . . . . O O . 2 3 | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B 1 4 | $$ . . . . . . . W X W | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

Obviously, Black wins.

Click Here To Show Diagram Code: [go]$$W White first $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . 2 O B | $$ . . . . . O O 3 4 . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B 1 . | $$ . . . . . . . W X W | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

Black makes mirror go, and gets jigo.

Click Here To Show Diagram Code: [go]$$W White first, variation $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O B | $$ . . . . . O O . 1 3 | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B 2 4 | $$ . . . . . . . W X W | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

This way Black gets jigo, as well.

Black wins the difference game, and never loses, so Dieter's play is superior. :bow:

Bill Spight · **#189**

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

So how do we know that that :w1:

-

sequence reverses? I confess that I overlooked the reverse at first. :oops:

I was surprised that White to play could win the difference game, but I am used to being surprised by difference games.

Still, it just seemed wrong. What conceivable position of the whole board could there be (with no kos) such that :w1:

is better than :w3:

?

This is a reverse because :b2:

is so good. It is good enough so that the position after :b2:

is equal to or worse than the original position for White. How can we tell that? With a difference game, of course.

Click Here To Show Diagram Code: [go]$$W Difference game 2 $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O . | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B . . | $$ . . . . . . . W X . | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

In this difference game we are comparing the original position (top) with the position after :bc:

(bottom). Now all we have to check is whether White to play can win the difference game. If not, then :bc:

reverses.

Click Here To Show Diagram Code: [go]$$W White first $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O 1 | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B . . | $$ . . . . . . . W X 2 | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

prevents the underneath connection, but then so does :b2:

, for jigo.

Click Here To Show Diagram Code: [go]$$W Variation $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . . O 2 | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B . . | $$ . . . . . . . W X 1 | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

If

connects, then so does :b2:

. We already know that White cannot win this game.

So White to play cannot win the difference game, and the :w1:

-

sequence is a reverse.

What is the other way to detect the reverse? Look at the first variation of the difference game. :b2:

was Black's best play if it was her turn in the original position. The exchange :wc:

-

has not eliminated it or made it worse. Black has not lost ground.

Let's check another sequence.

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

Conceivably this is another reverse. If so, White to play should not be able to win the difference game below.

Click Here To Show Diagram Code: [go]$$W Difference game 3, connects, at "a" $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . a 7 . | $$ . . . . X X X X X 3 | $$ . . . . . O O O X O | $$ . . . . . . . . O 1 | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X B B 2 | $$ . . . . . . . W X W | $$ . . . . . X X X O X | $$ . . . . O O O O O 4 | $$ . . . . . . . 9 8 5 | $$ . . . . . . . . . 0 | $$ --------------------[/go]

If

at "a",

at 8.

White wins, so that sequence does not reverse.

We might have guessed as much since the first line cut by White eliminated Black's best play in the original position.

Bill Spight · **#190**

I wrote:

Bill Spight wrote:

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

I confess that I overlooked the reverse at first. :oops:

I was surprised that White to play could win the difference game, but I am used to being surprised by difference games.

Still, it just seemed wrong. What conceivable position of the whole board could there be (with no kos) such that :w1:

is better than :w3:

?

I misspoke. Here is such a position. Of course.

Click Here To Show Diagram Code: [go]$$W Better $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . B O . | $$ . . . . . O O . . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X . . . | $$ . . . . . . . 1 X a | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

is better than "a", achieving jigo.

Click Here To Show Diagram Code: [go]$$W Even better $$ -------------------- $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . X X X X X . | $$ . . . . . O O O X O | $$ . . . . . . . B O . | $$ . . . . . O O 1 . . | $$ . . . . . . . X X X | $$ . . . . . . O . . . | $$ . . . . . . . O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ . . . . . . . X X . | $$ . . . . . . X . . . | $$ . . . . . . . O O O | $$ . . . . . X X . . . | $$ . . . . . . . b X a | $$ . . . . . X X X O X | $$ . . . . O O O O O . | $$ . . . . . . . . . . | $$ . . . . . . . . . . | $$ --------------------[/go]

The point of the exercise, however, is that :w1:

here is even better than "b".

But wait! If :b2:

is at "a", then the best that White can get is still just jigo. How can you say that :w1:

is "even better"?

Easy. Let's compare the two plays with a difference game. :lol:

Click Here To Show Diagram Code: [go]$$B Which is better, or ? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . O O O O O . . . . . . . X X X X X . | $$ | X O X X X . . . . , . . . . O O O X O | $$ | . X O . . . . . . . . . . . . . X O . | $$ | . . . X X . . . . . . . . . O O 2 . . | $$ | O O O . . . . . . . . . . . . . X X X | $$ | . . . X . . . . . . . . . . . O . . . | $$ | . X X . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . O O . . . . . . . . . . . . . X X . | $$ | . . . O . . . . . . . . . . . X . . . | $$ | X X X . . . . . . . . . . . . . O O O | $$ | . . . O O . . . . . . . . . X X . . . | $$ | . O 1 . . . . . . . . . . . . . . X . | $$ | O X O O O . . . . , . . . . X X X O X | $$ | . X X X X X . . . . . . . O O O O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

To do that we mirror the whole right side. Now we compare :b1:

on the left side with :w2:

on the right side.

Well, we have made the left side strict miai, haven't we? So we can ignore it and just look at the right side.

It looks familiar, doesn't it?

White to play wins, Black to play does not. So :w2:

is better than :b1:

.

Bill Spight · **#191**

Okigo Jizai

As some of you probably know, I am fond of Okigo Jizai, a 10 volume set of handicap go openings published in 1824 by Hattori Inshuku, founder of the Hattori School. I have posted material here from it several times. See, for instance, this thread. viewtopic.php?f=15&t=9409

Here are a couple of positions from the book for you to ponder. There is no plainly best play. But I like how Hattori treats them.

Click Here To Show Diagram Code: [go]$$Bcm10 2 stone game, Mini-Chinese $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . X . . . . . . | $$ | . . . , X . . . . , . . . . . X X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . 7 . 1 . . . | $$ | . . . X . . . . . , . . 8 2 . , 5 . . | $$ | . . . . . . . . . . . . . . . O 3 . . | $$ | . . . . . . . . . . . . . . . . 4 6 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

invades the Mini-Chinese position. (The Mini-Chinese is over 200 years old.

) Where to play next?

Click Here To Show Diagram Code: [go]$$Bcm12 3 stone game $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . . 2 6 . . . . | $$ | . . O , O . . . . , . . . 3 4 X . . . | $$ | . . O X . . . . . . . . . . 5 9 8 . . | $$ | . . X X . X . . . . . . . . . 7 O . . | $$ | . . . . . . . . . . . . . . . 0 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . 1 . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Hattori says that :b12:

is good, but Black has to be able to weather White's attack in the top right corner. :w15:

may be a bit of a surprise.

Click Here To Show Diagram Code: [go]$$Bcm22 3 stone game $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . 2 O O . . . . | $$ | . . O , O . . . . , . 3 1 X O X . . . | $$ | . . O X . . . . . 5 . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . 4 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . 7 6 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 8 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Hattori says that :b26:

is good, which it plainly is. White then plays inside Black's sphere of influence. How does Black respond?

Enjoy!

Kirby · **#192**

Click Here To Show Diagram Code: [go]$$Wcm25 3 stone game $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

If it were my game, I'd first try to make white heavy with a peep, and then I'd take territory on the bottom.

Click Here To Show Diagram Code: [go]$$Bcm1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . . . 2 1 . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . 3 . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

There are other moves that might give more pressure to black, but I don't seem to have a clear plan as to how to follow up:

Click Here To Show Diagram Code: [go]$$Bcm1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . X O . 1 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Since I don't see a clear way to profit as black, I'd prefer to just make white's group heavy and take territory immediately.

Good things might happen later.

Shaddy · **#193**

Consider this tewari?

Bill Spight · **#194**

Interesting comments, guys. Thanks.

I renewed my interest in Okigo Jizai when I ran across another book about openings, both even game and handicap, written in the early 20th century. What struck me was how similar the handicap openings were to most of those that I have seen in more modern books; that is, uninspired, and uninspiring. Black should play conservatively but not too defensively and avoid mistakes. That kind of thing. By contrast, I sense a spirit in Hattori's examples, as though he were asking himself, where would I play? There is a sharpness to the play that I find both refreshing and inspiring. (True, I sometimes think that he is setting up lessons, but that's OK, too.

)

Click Here To Show Diagram Code: [go]$$Bcm18 Tenuki $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . X . . . . . . | $$ | . . . , X . . . . , . . . . . X X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . 1 . . . . . . . . . . . . O . . | $$ | . . 2 . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . a . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . B . X . . . | $$ | . . . X . . . . . , . . O O . , X . . | $$ | . . . . . . 3 . . . . . . . . O X . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In the mini-Chinese example Hattori as Black tenukies. :shock:

There is a hint of that with :b16:

(

), which gives Black a bit of elbow room. Black is outnumbered locally, 6 stones to 4, both White groups are fairly strong, and Black has no base. It is as though, despite taking a handicap, Black were taunting White. C'mon, do your worst. I dare you!

Click Here To Show Diagram Code: [go]$$Wcm21 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . X . . . . . . | $$ | . . . , X . . . . , . . . . . X X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . O . . | $$ | . . O . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . 6 . . . . | $$ | . . . . . . . . . . . . . . . . 3 . . | $$ | . . . . . . . . . . . 4 . . . 2 1 . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . . X . . . . . , . . O O . , X . . | $$ | . . . . . . X . . 5 . . . . . O X . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White obliges with the jaw jab at 21. :w25:

seems a bit lenient to me, but it is sente, as Black cannot now omit :b26:

. Now the Black group has some eye shape.

Click Here To Show Diagram Code: [go]$$Wcm27 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . 2 . 1 . X . . . . . . | $$ | . . . , X . . 6 . , . . . . . X X . . | $$ | . . O . . . . . 5 . 3 . 4 . . . . . . | $$ | . . . X . . . . . . . . . . . . O . . | $$ | . . O . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . 7 . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . X . . . X O . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . . X . . . . . , . . O O . , X . . | $$ | . . . . . . X . . O . . . . . O X . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

looks funny, as it invites the ideal pincer at 28. However, if White plays on the left side right away Black will stake out a large framework on the top side. :w27:

prevents that with sente. Then :w33:

takes the last big point of the opening.

Both - and earlier - prevent the opponent from making an ideal position in sente, at the cost of leaving a weak group behind. There is a lesson there, but it involves judgement and the ability to handle the weak group if attacked. When you are giving a handicap, you usually can trust that you can weather any storm. What is surprising is that Hattori had Black play that way, instead of resting on the lead from the handicap.

Click Here To Show Diagram Code: [go]$$Bcm34 Leaning attack, plus $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . X . O . X . . . . . . | $$ | . . . , X . . X . 3 4 . . . . X X . . | $$ | . . O . . . . . O 5 O . X . . . . . . | $$ | . . . X . . . . . 6 7 . . . . . O . . | $$ | . . O . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . 1 2 . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . O . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . X . . . X O . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . . X . . . . . , . . O O . , X . . | $$ | . . . . . . X . . O . . . . . O X . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is a leaning attack against the White stones on the top side, but it also strengthens the Black group in the bottom right. Black does not want to get into a fight which puts that group in jeopardy. Black continues with a push through and cut on the top side.

Click Here To Show Diagram Code: [go]$$Wcm41 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . X . O . X . . . . . . | $$ | . . . , X . . X . X O . . . . X X . . | $$ | . . O . . . . . O X O 3 X . . . . . . | $$ | . . . X . . . . . O X 1 . . . . O . . | $$ | . . O . . . . . . . 2 . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . 5 . | $$ | . . . . . . . . . . . . . . . 4 . . . | $$ | . . . , . . . . . , . . . . . X O . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . O . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . X . . . X O . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . . X . . . . . , . . O O . , X . . | $$ | . . . . . . X . . O . . . . . O X . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White pushes through into the center and then Black continues the leaning attack with :b44:

.

Click Here To Show Diagram Code: [go]$$Bcm46 Black solidifies her gains $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . X . O . X . . . . . . | $$ | . . . , X . . X . X O . . . . X X . . | $$ | . . O . . . . . W X O O X . . . . . . | $$ | . 6 5 X . . . . . W X O . . . . O . . | $$ | 0 7 O 9 . . . . . . X . . . . O . . . | $$ | . 8 . . 1 . . . . . . . . . . . . O . | $$ | . . . 2 3 . . . . . . . . . . X . . . | $$ | . . . 4 . . . . . , . . . . . X O . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . O . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . X . . . X O . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . . X . . . . . , . . O O . , X . . | $$ | . . . . . . X . . O . . . . . O X . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Instead of continuing the attack, Black shifts to the left side and center. This exchange strengthens White and yields territory on the side, but it also strengthens Black and makes a territorial framework in the center. The :wc:

stones are weakened and have become difficult to save, if not impossible.

This is another lesson from Hattori. The White stones in the top are weak, but Black does not just singlemindedly attack them. Black is flexible. You often see attackus interruptus in Hattori's examples.

Click Here To Show Diagram Code: [go]$$Bcm56 Black returns to the attack $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . X . O . X . . . . . . | $$ | . . . , X . . X . X O . . . . X X . . | $$ | . . O . . . . . O X O O X . . . . . . | $$ | . O X X . . . . . O X O . . . . O . . | $$ | O 2 O X . . . . . . X . . . . O . . . | $$ | . O 1 . X . . . . . . 3 . . . . . O . | $$ | . . . O X . . . . . . . . . . X . . . | $$ | . . . O . . . . . , . . . . . X O . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . O . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . X . . . X O . . | $$ | . . . . . . . . . . . . . X . X . . . | $$ | . . . X . . . . . , . . O O . , X . . | $$ | . . . . . . X . . O . . . . . O X . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

takes kikashi on the left side and then :b58:

resumes the attack against the White stones on the top side. Note that the Black group in the bottom right, which was a liability, has become an asset.

Note also the skillful use of sente, first by Black in the invasion of the mini-Chinese position, then by White on the top side, and then by Black in the exchange on the left side.

Bill Spight · **#195**

The three stone game

Click Here To Show Diagram Code: [go]$$Wcm9 3 stone game $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . 1 . . 5 9 . . . . | $$ | . . O , O . . . . , . . a 6 7 X . . . | $$ | . . O X . . . . . . . . . . 8 . . . . | $$ | . . X X . 2 . . . . . . . . . 0 3 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . 4 . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is questionable. True, White has a good play on that point, but :b10:

makes the Black group on the left side somewhat overconcentrated. Players at that time accepted a bit more overconcentration than they do today, so Hattori probably thought that it was OK. Besides, he is setting up :w11:

.

Hattori praises :b12:

, which sets up a huge framework. But what about the top right corner? Black cannot secure it in one move, and it is not yet urgent. Students of Hattori will certainly not be following White around the board.

:b14:

is normal vs. :w13:

, but

may be a surprise. However, if White hanes at "a", Black at 17 would allow Black to quickly settle his group.

Click Here To Show Diagram Code: [go]$$Wcm27 Reduction $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . 2 1 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 3 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The shoulder blow, :w27:

, is a standard reduction of the Black framework. :b28:

and

are normal.

Reply to Kirby's peep:

Click Here To Show Diagram Code: [go]$$Bcm30 New Fuseki? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . 2 . . . . . . . . . . . . . | $$ | . . . . . . . 3 . . . . . . . . . . . | $$ | . . . . . 1 . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Black responds in New Fuseki style, with the keimas of :b30:

and

.

Hattori was not wed to any dogma.

Click Here To Show Diagram Code: [go]$$Wcm33 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . 4 5 . . . . . . . . . . . . . . | $$ | . . X 1 . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . . 2 . . . . 7 . . . . . . . . . . . | $$ | . . 3 O . O . . . 8 . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . . 6 . . X . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . 9 . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

prevents White from playing there, which would make good shape. Note that Black does not reply to :w37:

, but blocks off the corner and prevents White from making a base on the side. Hattori says that the keima at 40 is good. It is as though Hattori were channeling Takagawa from the future.

invades. I like how Hattori has Black handle the invasion.

Click Here To Show Diagram Code: [go]$$Bcm42 Sacrifice $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . 7 . . | $$ | . . X . . . . O . . . . . . . . . . . | $$ | . . O O . O . . . X . . . . . . . . . | $$ | . . . . . . . X . . . . . . . 5 . . . | $$ | . . X . . X . . . . . . 6 . . . . . . | $$ | . . . X . . . . . , . . 3 4 . X . . . | $$ | . . . . . . . . . X . 2 . O . 1 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

secures the corner and then :b44:

is a normal tesuji. Black sacrifices :b44:

to stake out the bottom right side. :b48:

is the last big play of the fuseki.

Click Here To Show Diagram Code: [go]$$Wcm49 White fights back $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . X O . . . . . . . . . . . . . . | $$ | . . X O . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . X . . | $$ | . . X . . . . O . . . . . . . . . . . | $$ | . . O O . O . . 9 B . . . . . . . . . | $$ | . . . . . . . X 7 . . 0 . . . X . . . | $$ | . . X . . X . . 4 1 3 . O . . . . . . | $$ | . . . X . . . 6 5 2 . . X O . X . . . | $$ | . . . . . . . . 8 X . O . O . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

in quite a nice play, isn't it?

In the resulting battle White sacrifices :w53:

to cut off :b40:

(

). But then :b58:

is a good peep. Hattori leaves things in media res.

I think you can see why I like Okigo Jizai.

Kirby · **#196**

One thing that I have observed in the past year or so is that "rules" don't apply all of the time, especially when weak groups are involved.

From an empty board, black's play might seem odd:

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

Moves

and

, above, seem to be "floating". For example, it's not even clear to me that the territory is solid, as there seems to be aji in black's position:

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

If black wanted to secure territory in this area, the "floating stones" would make more sense if they were lower:

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

Now the position is much more clear.

But in the game, there is a weak group involved:

Click Here To Show Diagram Code: [go]$$Bcm30 New Fuseki? $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . X W . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . W . W . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . . . . . X . C . . . . . . . . . . . | $$ | . . . X . C C C . , . . . . . X . . . | $$ | . . . . C C C C . X . . . . . . . . . | $$ | . . . . C C C C . . . . . . . . . . . | $$ | . . . . C C C C . . . . . . . . . . . | $$ ---------------------------------------[/go]

The prospects of black making territory in the marked area seem much higher, due to white's weak group. The same aji might exist as on the empty board, but white can't really think about exploiting it, since white's other group is weak.

As white saves the group, black will naturally get more than if he played a "normal" move as what came to my mind (ignoring the peep, which may be questionable):

Click Here To Show Diagram Code: [go]$$Bcm30 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . O . O O O . . . . | $$ | . . O , O . . . . , . X X X O X . . . | $$ | . . O X . . . . . X . . . . X X O . . | $$ | . . X X . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . X O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . B . . . , . . . . . X . . . | $$ | . . . . . . . . . X . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

skydyr · **#197**

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

Well, even in a position like this but without the weak group, a move like :b1:

has some merits because it builds on the black group up the left side and on the top. The tewari presented (5 white star point stones) is very different from this, to the point that regardless of what black played on the bottom, it would feel like black has already fallen behind.

Kirby · **#198**

skydyr wrote:

The tewari presented (5 white star point stones) is very different from this, to the point that regardless of what black played on the bottom, it would feel like black has already fallen behind.

Sure. The only thing I want to describe is the feeling I have gotten that the "rules" change when weak groups are involved.

It's difficult for me to articulate this well, but nonetheless, interesting to me.

ez4u · **#199**

Interestingly 18 below is not found in GoGoD as far as I can see. Invariably Black connects with the attachment at 'a' instead. That applies whether you are Onoda Chiyotaro playing Hashimoto Utaro in 1936 or Cho Han-seung playing Gu Li in 2013.

Click Here To Show Diagram Code: [go]$$Wcm9 3 stone game $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . 1 . . 5 9 . . . . | $$ | . . O , O . . . . , . . a 6 7 X . . . | $$ | . . O X . . . . . . . . . . 8 . a . . | $$ | . . X X . 2 . . . . . . . . . 0 3 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . 4 . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Bill Spight · **#200**

Igo Tsumekata (How to play tsumego) is another ancient book I kind of like. I haven't worked through it all yet, though.

It is by Kobayashi Tetsujiro, 6 dan, and his son, Kentaro, published in 1901. Link to online copy in the Japanese National Library: http://dl.ndl.go.jp/info:ndljp/pid/861034

Here are a couple of problems, one easy, one not.

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]

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

Enjoy!

This 'n' that

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