Which is bigger, A or B?

BlindGroup · **#41**

dfan wrote:

I was White, and Black just played :b1:

, which we both assumed was sente, because of the threat of a. But Crazy Stone strongly prefers for White to give the group up and tenuki (e.g., at b), because Black has not only spent two moves to kill the upper left group, they're two moves that in retrospect are deep inside his own territory. My opponent and I were both very surprised afterwards to hear its opinion.

My reaction to this was different. What do you all think? I see white with two weak groups on the left, either of which can be settled in one move. So, which to prioritize?

Prioritize top group:
1. Sizable number of points.
2. More easily killed than middle group.

Prioritize middle group:
1. Sizable number of points.
2. More strategic value than top group because top group is surrounded.
3. Black can harass this group to build territory on the bottom by playing the marked stone below. The value of the territory on the bottom could be sizable.

So, this seems to point to b as the right move.

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

gowan · **#42**

John Fairbairn wrote:

Quote:

A few years ago at the US go congress, a friend and I were talking to Maeda sensei, and he told us that, apart from the endgame, sente is bad. Now, granted he was addressing this to a 5d player so it shouldn't be taken entirely literally, but his reasoning was basically that sente gains nothing since it's your privilege anyways, and that gote moves are the ones that confer real gains.

Yes. And one of the real gains of gote moves (by which we should really understand honte moves and the like) is that they leave behind sente moves - usually more than one. This is the basis of the classic book on "Gote no sente" by Sekiyama Riichi. This in turn is based on kendo, and it is worth viewing through that prism. If we try to visualise ourselves in a sword fight where the opponent comes rushing at us, I suspect most of us are likely to imagine ourselves deftly retreating (gote) rather than rushing back at him or running away (tenuki). That's because we like to see ourselves as not just brave but clever, so we would take time to think and imagine ourselves doing the serenely clever stuff. Our minds are more important than our swords.

But stones in go are not as sharp as swords and that dulls our responses. In go, amateurs tend to think the clever stuff is to resist the opponent's sente with kiai or to tenuki. That's often just grandstanding. Strong players will rather just accept gote and wait for the chance to strike back later on.

That's fine as far as it goes, but a truly strong player also has the ability to assume a gote position even when not faced with an immediate threat. In simplest terms in go this translates into making bases and honte.

Another point to mull over is that kiai is badly translated as "fighting spirit." This tends to conjure up Rambo-esque behaviour in western amateurs. The term just means matching your ki (qi) with your opponent's. That can cover fighting back immediately, of course, but it can also mean taking up a gote position so that your yin matches his yang. But in either case the point to be alert to is that this is not a static match. You are supposed to be trying to have the momentum move in your favour. That may mean tempting the sente opponent to overreach (in go that may include getting him to lose his future options or fill in liberties by playing his sentes too early). It may instead mean coiling up like a spring in a gote position. In go, as Sekiyama teaches, the important thing to take away about gote is to play it so that it likewise represents a coiled spring. If you play a gote that has no spring in it, you have possibly made an inefficient move somewhere along the line, and it is always worth tracing back to see where. It's surprisingly common to see that the inefficient backtracked move turns out to have been a sente when a gote would have been better.

(To forestall the usual questions, I don't think Sekiyama's book is in print. I think my copy is from the 1940s.)

Many amateurs think that in the endgame the correct way to play is to take all the sente points possible consecutively until they have to give sente to the opponent. However, depending on the position of course, taking gote "prematurely" allows one to get better moves later, such as tedomari, when your opponent runs out of sente.

Bill Spight · **#43**

Kirby wrote:

Uberdude wrote:

Kirby wrote:

the hane on the 1st line under :b1:

could theoretically be answered with a throw-in to the left of the hane, and if white captures, black could play to the right of the hane. White could then cut and cause a ko.

White would probably tenuki as he's lived in sente, later Black would take the ko threatening to kill and white answers, and even later in endgame white retakes ko and black connects to avoid ko. So it almost ends up the same as no throw in.

True, White gets a sente move if he tenukis, compared to just capturing. But in this case, black captures the original hane in sente, too.

It's probably better than just capturing to begin with like you suggest, but it seems a little weird to allow your stone to be captured in sente. Why not just descend directly, threatening endgame on the top later?

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

Maybe the value of sente is big enough that black wouldn't respond? In which case, the hane ends in gote and gets two more points?

This sagari is an interesting play.

If the left side becomes no man's land it is 1/2 point better than simply taking the stone. (It gains 1 pt. on the top and loses 1/2 pt. on the left.) Also:

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

does not threaten to kill the corner. This may or may not matter for the fight on the left side.

That aside, the sagari is worth about 7-8 pts. less than the hane.

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

That's because of the sente jump to :w1:

. For reference:

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

We could reach the same position via an earlier monkey jump. The proverb says that the monkey jump gains 8 points.

The throw-in doesn't really help Black in this regard.

Click Here To Show Diagram Code: [go]$$Wc $$ +---------------------------------------+ $$ | . W c W . 1 . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | a B O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Yes, White will have to capture :bc:

before filling at "c", but that is really not a problem.

Click Here To Show Diagram Code: [go]$$Wc Ko $$ +---------------------------------------+ $$ | . W . W B . . . . . . . . . . . . . . | $$ | . O O X a . . . . . . . . . . X X O . | $$ | . B O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

In this kind of position White may well not wish to start the ko with a play at "a" because the corner group is at stake. Then, as Uberdude suggests, play is likely to go this way.

Click Here To Show Diagram Code: [go]$$Bc Sente ko $$ +---------------------------------------+ $$ | . W 1 W B . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | 2 B O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Black takes the ko in sente, as White secures the group. Later on:

Click Here To Show Diagram Code: [go]$$Wc Sente ko $$ +---------------------------------------+ $$ | . W B 1 B . . . . . . . . . . . . . . | $$ | . O O X 2 . . . . . . . . . . X X O . | $$ | W . O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

With the White group secure, :w1:

threatens to enlarge the ko with an atari at 2. Usually there is a ko fight, but the normal result is that Black ends up protecting with :b2:

, leaving a 1/3 point ko.

By allowing White to live with sente Black loses 8-9 points in the corner. Not to mention allowing White to go back and protect his group in the center left. That would be a horrendous error. :shock:

White's hane to live gains around 17 points, more than most plays in the opening. CrazyStone does not evaluate by points, so I wonder if its reckoning was based upon the hane or a lesser way to live. Perhaps the hane gives the White group a lower probability of living in pseudo-random playouts than the capture or the sagari. In that case, the program's evaluation may be off.

dfan · **#44**

My game position was more interesting than I realized! Thanks to everyone for their comments.

Kirby · **#45**

I'd like to clarify something regarding this comment, which I don't get.

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

Here, white takes gote. But a play at 'x' is white's privilege - it's sente for white, but gote for black.

So later in the game, we can assume that white will get to push:

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

So that will be the final position.

Contrast this with the hane:

Click Here To Show Diagram Code: [go]$$Wc $$ +---------------------------------------+ $$ | . . . 1 z y . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

is playing at 'y' white's privilege? I'm not so sure. If things play out as suggested with the throw-in variation that was provided here, this was the final variation:

Click Here To Show Diagram Code: [go]$$Wc Sente ko $$ +---------------------------------------+ $$ | . W B 1 B w . . . . . . . . . . . . . | $$ | . O O X 2 . . . . . . . . . . X X O . | $$ | W . O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Black has one more point at 'w' in this variation, and the option of later taking the ko.

I don't understand how we can assume the jump at 'y', above, since it's not clear to me that this is black's privilege, given the throw-in variation.

So I don't completely understand the comment that the sagari is 7-8 points less than the hane. It only makes sense to me if we assume the jump at 'y', but I don't see how this will happen given the throw-in variation.

sorin · **#46**

About the first question in the thread: capturing in the corner is 22 points in gote. It is a huge move, I would definitely play there with white.

If white plays hane instead, I would definitely play there with black.

Bill Spight · **#47**

Kirby wrote:

I'd like to clarify something regarding this comment, which I don't get.

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

Here, white takes gote. But a play at 'x' is white's privilege - it's sente for white, but gote for black.

So later in the game, we can assume that white will get to push:

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

So that will be the final position.

Contrast this with the hane:

Click Here To Show Diagram Code: [go]$$Wc $$ +---------------------------------------+ $$ | . . . 1 z y . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

is playing at 'y' white's privilege? I'm not so sure.

You don't think that 'y' is White's sente?

Quote:

If things play out as suggested with the throw-in variation that was provided here, this was the final variation:

Click Here To Show Diagram Code: [go]$$Wc Sente ko $$ +---------------------------------------+ $$ | . W B 1 B w . . . . . . . . . . . . . | $$ | . O O X 2 . . . . . . . . . . X X O . | $$ | W . O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Black has one more point at 'w' in this variation, and the option of later taking the ko.

I don't understand how we can assume the jump at 'y', above, since it's not clear to me that this is black's privilege, given the throw-in variation.

So I don't completely understand the comment that the sagari is 7-8 points less than the hane. It only makes sense to me if we assume the jump at 'y', but I don't see how this will happen given the throw-in variation.

Well, that throw-in variation makes White saving his group sente. And a large sente, at that, worth about 25 points. The variation where Black tenukis and allows White to continue with the jump to "y", makes White saving his group gote. If the jump to "y" is sente, that gote gains only about 17 points. But it is true that I did not work out the White follow-up after "y". I assumed that it was worth more than 8 points, because the Black area is open, and because of my knowledge of the value of another one space jump on the edge in more enclosed situations, and because the traditional value of the monkey jump agrees with my calculations. But I did not calculate the follow-ups, and the follow-ups after that, etc., which would have been necessary to get a precise value. Your objection has made me reconsider. One thing is that, because the Black territory is open, Black does not have as good a reply to the jump to "y" as when the territory is more closed. So maybe the jump to "y" is not sente, because it has gained so much already.

Maybe the White follow-up gains only 6 points or so. (I hardly think it can gain less. My admittedly imperfect influence function estimates the gain at about 8 points. It assumes that all the stones are alive, which does not seem too far off base here.) Anyway, on the assumption that the jump to "y" is gote, with a follow-up that gains only 6 points, the hane gains about 16 points instead of 17 points. The hane is still clearly better than the sagari, and it is gote.

Kirby · **#48**

Well, I don't know if 'y' is sente or not. I was confused because I thought the throw-in variation was the better one, and if so, the sagari is not worse than the hane since it reduces black by more points on the top.

But it sounds like you're saying that the throw-in variation is worse since it lets white live in sente. I suppose that's true, but it's not intuitive to me since black captures white's hane stone.

Also, I wasn't objecting so much as asking for clarification. I know almost nothing about the endgame.

Bill Spight · **#49**

Kirby wrote:

Well, I don't know if 'y' is sente or not. I was confused because I thought the throw-in variation was the better one, and if so, the sagari is not worse than the hane since it reduces black by more points on the top.

But it sounds like you're saying that the throw-in variation is worse since it lets white live in sente. I suppose that's true, but it's not intuitive to me since black captures white's hane stone.

Also, I wasn't objecting so much as asking for clarification. I know almost nothing about the endgame.

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . 3 2 1 4 . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

After

White is alive, right?

Kirby · **#50**

Bill Spight wrote:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . 3 2 1 4 . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

After

White is alive, right?

Yeah, I don't dispute that it's alive in sente. Maybe I just didn't realize why it was a bad variation. For example, if black just leaves it:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . 3 2 1 z y . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

I don't know if white will get the jump at 'y' or if black will get the block at 'z'. Maybe the point is, since 'y' is probably sente, we can assume white will get 'y'?

Intuitively, it seems that black's followup to 'z' is sente, so it would be most likely that black would get 'z'.

If that's the case, I'd compare this diagram for the hane:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . 3 2 1 4 . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

to this variation for the descent:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . . 1 3 5 6 . . . . . . . . . . . . . | $$ | . O O X 4 . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

The descent is easier for me to understand, since the ko isn't involved, so maybe I'm not making a fair comparison.

Bill Spight · **#51**

Kirby wrote:

Bill Spight wrote:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . 3 2 1 4 . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X b . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

After

White is alive, right?

Yeah, I don't dispute that it's alive in sente. Maybe I just didn't realize why it was a bad variation. For example, if black just leaves it:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . 3 2 1 z y . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

I don't know if white will get the jump at 'y' or if black will get the block at 'z'. Maybe the point is, since 'y' is probably sente, we can assume white will get 'y'?

Intuitively, it seems that black's followup to 'z' is sente, so it would be most likely that black would get 'z'.

If that's the case, I'd compare this diagram for the hane:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . 3 2 1 4 . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

to this variation for the descent:

Click Here To Show Diagram Code: [go]$$Wc Lives in sente $$ +---------------------------------------+ $$ | . . 1 3 5 6 . . . . . . . . . . . . . | $$ | . O O X 4 . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

The descent is easier for me to understand, since the ko isn't involved, so maybe I'm not making a fair comparison.

The last diagram is gote, not sente.

Kirby · **#52**

Bill Spight wrote:

The last diagram is gote, not sente.

True. It lives in gote.

In the throw-in variation, black will probably tenuki at this point in the game, leaving the position here:

Click Here To Show Diagram Code: [go]$$Wc $$ +---------------------------------------+ $$ | . 3 2 1 y z . . . . . . . . . . . . . | $$ | . O O X C v . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . , . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . X . X . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . O . O . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Now, there are two possibilities I see here:

If black plays at 'y', white can live in sente (assuming black can't afford to fight a ko if white plays at the marked intersection).
Black never gets the chance to play at 'y', and white plays at 'z' (or 'v' if white feels ambitious about the ko situation).

The first option is not black's privilege since it will end in gote (unless black can win all ko threats, I guess?). The second one may be white's privilege, depending on whether it's sente, I guess?

So can we assume that the second possibility is the one that's more likely to happen under optimal play?

Kirby · **#53**

I guess there's also the situation where there is no throw-in at all:

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

I guess black should probably play at least 'y', because if white ignores to play sente somewhere else, black captures the hane stone in sente.

So if black plays 'y', white can either answer or not answer:
1.) If white doesn't answer, black captures the hane stone in sente, and it's questionable as to whether the hane was better than living in gote - maybe it is, if the other sente is big enough (?)
2.) If white answers, black will almost certainly tenuki, but later cut at the marked spot, I guess:

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

which is probably sente, I guess, but is more in points than sagari, anyway, so maybe that shows it's better.

I think I'm confusing myself at this point, but maybe I'll take a break and think about it a little bit more later.

Bill Spight · **#54**

Kirby wrote:

I guess there's also the situation where there is no throw-in at all:

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

I guess black should probably play at least 'y', because if white ignores to play sente somewhere else, black captures the hane stone in sente.

So if black plays 'y', white can either answer or not answer:
1.) If white doesn't answer, black captures the hane stone in sente,

If White doesn't answer, Black kills.

Kirby · **#55**

Bill Spight wrote:

If White doesn't answer, Black kills.

Yes, good point :-)

Uberdude · **#56**

Kirby, if you have doubts about the one space jump after ignored hane being sente, why do you think push after your descent is sente?

Kirby · **#57**

Uberdude wrote:

Kirby, if you have doubts about the one space jump after ignored hane being sente, why do you think push after your descent is sente?

Well, the two are similar in that regard. What's most unclear to me is the throw-in variation with the ko. If black has ko threats, practically speaking, it seems black may be able to block at 'y' in sente.

But I guess I think it's more likely that white lives in sente since black has to eventually take the ko.

I guess I lean toward thinking the hane is better than descending, but I can't say I have my head wrapped around the position.

Uberdude · **#58**

Kirby wrote:

Uberdude wrote:

Kirby, if you have doubts about the one space jump after ignored hane being sente, why do you think push after your descent is sente?

Well, the two are similar in that regard. What's most unclear to me is the throw-in variation with the ko. If black has ko threats, practically speaking, it seems black may be able to block at 'y' in sente.

But I guess I think it's more likely that white lives in sente since black has to eventually take the ko.

I guess I lean toward thinking the hane is better than descending, but I can't say I have my head wrapped around the position.

Hmmmm, you still seem to be confused. So if white hanes then if black blocks directly white is still not alive (a17 still kills, the exchange didn't help white):

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

So to be consistent with the first move white would connect and live. This leaves a 1st line cut of some fairly large endgame value that black may or not defend with his sente (probably not in this game).

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

If white hanes and black throws in then white takes. White is now alive, the throw in helped white live as a17 no longer kills.

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

Black now has sente, but white is already alive. Black could choose to place a stone at y (which he already had if he didn't throw in!) and it looks like below.

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

Usually black doesn't need to worry much about the ko cut, because taking the ko is sente for him to kill the corner, so it likely ends up looking like this after he takes the ko and later white takes back and black defends. So black closed the top, but took gote to do it. It's like you decided to defend the cutting point after diagram 2, but maybe another move is bigger.

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

So if you want to compare with the descend, you need to compare with a white living in gote variation in which black didn't help white live, so:

Click Here To Show Diagram Code: [go]$$Wc White lives in gote with hane $$ +---------------------------------------+ $$ | . . 3 1 2 . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . |[/go]

vs:

Click Here To Show Diagram Code: [go]$$Wc White lives in gote with descend $$ +---------------------------------------+ $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . |[/go]

In the first white's endgame follow up is cutting and taking a load of points, let's say black plays 2 to stop white breaking in there:

Click Here To Show Diagram Code: [go]$$Wc follow-up after hane $$ +---------------------------------------+ $$ | . . O O X 3 7 5 6 . . . . . . . . . . | $$ | . O O X 1 . . 4 8 . . . . . . X X O . | $$ | . X O X 2 X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . |[/go]

vs the smaller reduction:

Click Here To Show Diagram Code: [go]$$Wc follow-up after descend $$ +---------------------------------------+ $$ | . . O 1 3 4 . . . . . . . . . . . . . | $$ | . O O X 2 . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . |[/go]

Bill Spight · **#59**

Just to follow up a bit on Uberdude's analylis.

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

Globally, we agree that Black plays tenuki now, rather than let White live with sente. Let's do a little tewari.

Click Here To Show Diagram Code: [go]$$Wc Sagari with White sente follow-up $$ +---------------------------------------+ $$ | . . 1 3 . . . . . . . . . . . . . . . | $$ | . O O X 4 . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . |[/go]

If White lives with the sagari and later takes his local sente with :w3:

,

is obviously correct.

Click Here To Show Diagram Code: [go]$$Wc Variation $$ +---------------------------------------+ $$ | . . 1 3 4 . . . . . . . . . . . . . . | $$ | . O O X . . . . . . . . . . . X X O . | $$ | . X O X . X . . . . . . . . X . X O . | $$ | . O X , . . . . . , . X . . . X O . . | $$ | . O X . . . . . . . . . . . . X O O . | $$ | . X X X . . . . . . . . . O X O X X . | $$ | . . O X . . . . . . . . . . O O O . . |[/go]

is incorrect. But it duplicates the position in the first diagram, which indicates that :b2:

in that diagram is wrong.

Kirby · **#60**

Uberdude wrote:

Hmmmm, you still seem to be confused.

Oh, I don't doubt it! :-)

Actually, though, your analysis mostly makes sense, but what hangs me up is this (bold part added by me):

Uberdude wrote:

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

Usually black doesn't need to worry much about the ko cut, because taking the ko is sente for him to kill the corner, so it likely ends up looking like this after he takes the ko and later white takes back and black defends. So black closed the top, but took gote to do it. It's like you decided to defend the cutting point after diagram 2, but maybe another move is bigger.

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

Since the ko situation is not clear to me, it's not clear to me that black has to defend at the marked stone in the position above.

So it's not as straightforward to me as a position that is 100% gote for black.

That's why the descent is much easier for me to understand:

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

Black clearly ends in gote, so I can see the end result.

But here:

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

Is the marked intersection necessary? It's not as clear to me.

So if we assume that black must defend this spot and gets gote, then I can compare it apples-to-apples with the descent variation where I know black gets gote.

Since it seems theoretically possible for black to block off in sente here due to an unknown ko situation, it's hard for me to feel completely satisfied.

In practice, the ko is probably too heavy on black, so it's basically as good as black having gote.

But it just bugs me a little bit that it seems like it could be sente.

I guess I just have to accept that black cannot afford to take sente in this situation, and if I treat that as an absolute, then we can say that white absolutely lives in sente if black does the throw-in.

And in that case, I guess doing the throw-in is not a good move, and not a variation we should compare.

Which is bigger, A or B?

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