# BQM 271

### The Question

Basic Joseki 5

revo: The diagram shows a basic 3-4 point joseki. In "38 Basic Joseki", section 5, page 46 shows the following continuation if white tenukis:

continuation

For the completion of this variation, see the section of 3-4 point high approach outside contact, tsukehiki hanging connection labeled Black Tenuki.
And then the authors say, that if would be at 8, white would play at 7 and win the semeai in the corner. Well, I've tried hard, but I didn't find a way for white to win the corner race after these moves:

white to win the semeai in the corner

I've tried a lot of variations, the best result I got for white was a ko she takes first. Can someone show me a sequence how white can capture these three black stones unconditionally?

### First Suggestion

LaTomate: I'd say play 8 as follows instead:

white to win the semeai in the corner

Might continue this way is black cuts...

white to win the semeai in the corner - black cuts

Of course, I'm not sure, but this is what I see. If black cuts, I feel he is at an advantage, seeing all the thickness he's getting.

Bill: But doesn't Black do better by giving up only one stone in the corner? The exchange, - , looks good for White.

### Second Suggestion

revo: I think I finally got a possible sequence. I assume that the black moves are already the strongest. If they're not, please show me my mistakes :)

white wins
white wins

### Regarding the Second Suggestion

Alternative

Velobici: Strikes me that may be better for Black. makes straight shape. Straight shape is useful in fighting. seems to be a key point as well. Now Black has four liberties to White's four liberties, but if White plays at a before b, it seems that she hastens her own death by taking an inside liberty first. When White saves a for the last move (the capturing move), she must play c before b, thereby effectively giving Black an additional liberty.

revo: I think that doesn't work for Black, cause White will play at . Black must play at a now, otherwise White would live unconditionally. And if Black plays a, he will be short of liberties. So Black can only play at the point of . He can build an eye then and will have enough liberties. Thats why White can't block at the point to the left of and White will have to live by a. Then black can live too by extending left of .

Dave: First of all how will B continue if is at 4 instead? Black can never make eyes in the corner so if White pokes her head on the right side, the corner is dead.

Killing the corner?

Dave: I believe that w5 here is the answer to the original question.

Killing the corner - not

Dave: Hmmm... I quess I was wrong. We are back to White taking a ko first.

Killing the corner - again :-)

Dave: OK, simple is best?

QWerner: Well, my solution looks simple, do I miss something?

Till here is no ohter variation

If Black playes elsewhere and white get 3, white will win. When black plays 3 white has to play 4 and black must block with 5.

Black loss

Black loss with all moves a - d.

Black ko?

at 5

Dave: I think there is no way for White to avoid ko after Black plays in at .

Killing the corner - review

I thought not playing the hane made a diffence, but I do not think that I was correct. This arrives at the same position by transposition. Black gets a ko.

Good ko for White

dnerra: The ko is extremely good for White. is a ko threat, so Black has to find the first non-local ko threat, AND black has to make an approach move at a, AND it is still a two-stage ko after that.

Fair enough to consider this a win for White.

ilan: This variation appears in a game between Shusaku (Black) and Genan Inseki (White) following the move under the star point (colours reversed in the diagram):

Shusaku vs. Genan Inseki
fills

Dave: After reviewing the literature and professional practice, I think that we can conclude that the original statement in 38 Basic Joseki is incorrect. Black can not be killed outright.

Igo Daijiten

In Igo Daijiten it comments that the exchange of for allows White to kill a corner invasion outright. There is no analysis of the case where Black pulls out the invading stone when is not present.

continuation
continuation

The marked stone is in the right position to protect the cut.

In professional play there are a few examples of pulling out the stone. I could find no example where Black resorts to the ko so I think that dnerra's assessment that this is too favorable for White is correct. Mainly Black pulls out the stone and either:

• Sacrifices the stones in order to close off the top (see game 1 below), or
• Makes a gote seki in order to force White from the outside (see game 2 below)

Game 1 - Go Seigen - Kajiwara Takeo 1959-04-29

Go Seigen - Kajiwara Takeo 1959-04-29

Here Kajiwara sacrifices the cutting stones by playing in order to ensure sente for the pincer at . Notice that the two marked stones have been exchanged but the Black stone is differently placed than the Igo Daijiten case above, the White stone does not protect the cutting point if White descends with .

Game 2 - Kirimoto Kazuo - Mizokami Tomochika 1993-04-07

Kirimoto Kazuo - Mizokami Tomochika 1993-04-07

Here White has played the marked stone and Black has ignored it. Black responds to by sliding to but White intercepts with and ...

Game 2 diag 2

Now White proceeds to wall off the right side, getting payback for the marked stone played earlier.

Game 2 diag 3

White builds the wall to the edge but turns back to rather than connecting .

Game 2 diag 4

is an interesting play. This makes the seki gote for White. Note that if were a hane at 3, Black would have to connect to avoid a ko after , giving sente to White. Now Black plays a ladder breaker at , forcing White to connect at . This gives Black the chance to play . White's wall in the upper right is very impressive, however Black has meanwhile played multiple times on the bottom. The result was a win for Black. I think this game gives a good indication of the overall opportunity for the invader here. The invader need not die, but there is not a lot to gain.

BQM 271 last edited by DaveSigaty on January 19, 2006 - 02:01