Good Empty Triangle

  Difficulty: Intermediate   Keywords: Joseki, Shape

Table of contents Table of diagrams
Joseki (a)
Related joseki
Mutual good shape
Joseki (b1)
Joseki (b2)
Joseki (c)
Black to play
Good empty triangle
Bad empty triangle
2 empty triangles - is the 2nd one unnecessary?
better a forcing move instead of an own empty triangle?
if Black tries too hard
Black continuation

Descent Variation
fighting emty triangle - white's next move?
The third "Ghost" of the "Blood Vomiting Game"
Shape #7.2: Three possible patterns for White.
Shape #7.3
Shape #7.4
here the empty triangle is a brilliant move
B2 is the correct local endgame, afa[i|tapir]k
Gu Li (W) - Qiu Jun, 2005 Agon-Kiriyama Cup Final
Gu Li (W) - Qiu Jun (ii)
Gu Li (W) - Qiu Jun (iii)
Gu Li (W) - Qiu Jun (iv)
Gu Li (W) - Qiu Jun (v)
Ushinohama(W) vs Takemiya(B)

Efficiency is one aspect of shape. Late in the game, especially, it can be obviously correct to make an empty triangle and making an empty triangle can also be the vital point. A good empty triangle is an instance of what the Japanese call guzumi.

Example 1 - Joseki (a)

[Diagram]
Joseki (a)  

B2 is the vital point, even though it is an empty triangle.

[Diagram]
Related joseki  

B2 makes "good shape" but becomes overconcentrated.

unkx80: I don't think it's so much about overconcentration. I believe that it's got more to do with destroying White's eye shape.

Bill: Well, it is a question of emphasis, isn't it? Anyway, let's take away the black+circle stone.

brindis: Just a question, why not 2 at 'a'?

Serpent: Because doing so would open the black stone above 1 to atari.

(Sebastian:) I don't see that. That black stone has three liberties, reduces W1's liberties to two, and it can easily be connected if need be.

[Diagram]
Mutual good shape  

This is fine for both players, no? Black does not need an extra stone.

Eagle : Tewari analysis may show that the black shape is overconcentrated, but i think in practice the second diagram is nothing worse than the first one (i think it's better , may be just because i missed something ) .It's worse than the third diagram,not the first diagram . Am i wrong ?

corwin: To my eyes, the biggest difference in the two diagrams is that black ends in sente in the first, and gote in the second.


Example - Joseki (b)

[Diagram]
Joseki (b1)  

tderz: After the unreasonable cut W1, the continuation to B6 gives Black the miai of either a or b,
hence B6 is a 'good empty triangle'. (source: Ishida a.o.)

[Diagram]
Joseki (b2)  

Similar is this 5-4 Joseki, where white's empty triangle would be a good tesuji to punish Black's overplay-cut: black+square is an overplay, which empty triangle white+circle helps exploiting. After 4 moves, the cutting stones black+triangle are capured. [source: D.Ormerot, http://gogameguru.com/5-4-openings]


Example - Joseki (c)

[Diagram]
Joseki (c)  

B2 (empty triangle) is often a good way to respond to White's 3-3 invasion in this shape.

(Sebastian:) Indeed, this is not uncommon, with 26 pro games played this way (according to SmartGo's library) only second to 'a', which occurs 49 times. And it occurs more frequently in games that led to a win. But why? What are its advantages over 'a'? (Later:) I found this discussed here, so I see some difference to 'a' now, but I'm still not convinced that it's superior.


Example 2 - Tesuji

[Diagram]
Black to play  

This problem comes from the Tesuji Dictionary, by Segoe Kensaku and Go Seigen. They say that if you get this one right, you are 5 dan. (Of course, you have a big hint. ;-))

Solution


Example 3 - Middle Game Joseki: "guzumi"

[Diagram]
Good empty triangle  

The sequence of W1 to W5 is one of the best ways of escaping with the lone white stone at the top. W5 makes the empty triangle and then White has a rather clear exit, while aiming for the cutting point at a (at the correct time).

[Diagram]
Bad empty triangle  

W3 here would be a mistake. B4 plays at the vital point, destroying White's eye shape, and forcing W5 to connect with a bad empty triangle.

Bob McGuigan: Here's an example from one of my own games (I was Black) where Black responds to a White empty triangle move by making one too. White's empty triangle looks good but after Black's response ...

[Diagram]
2 empty triangles - is the 2nd one unnecessary?  

B2 in response to W1 is good defense. W3 creates a cutting point in Black's shape. B4 takes a liberty from White and leaves a lot of aji against White's group.

[Diagram]
better a forcing move instead of an own empty triangle?  

tderz: Interesting position. (yet I think black's empty triangle is not necessary)
B1 is tempting too - a & b seem miai now.
It is the same technique as in above joseki.

The white cut c seems far fetched with the created white weakness e.
If White wants to solidate first at at f, cutting through with black d would be possible
(resp. Bg, after white q, she cannot cut at r),
however, if replying B1 with white d one has forced white to be very submissive (which is the intention of B1) and could hane oneself with f.
Can White survive?

Yes, Wd - Be - Wg - Bf - then k (or l, smaller).

[Diagram]
if Black tries too hard  

tderz: other ways for White to avoid an empty triangöle?
Perhaps not, after W3 (protecting against the cut y) to W5, there is still no connection to the left white+square, due to Black x (if Black a to white j have been exchanged),
but white cut capture at k and had no problems.

Theoretically, the black black+square could become a target after W1 ot W5, if Black tries too hard with black a to i?


Example 4 - forcing down

[Diagram]
Black continuation  

Example 5 - historic master games

Game Dosaku - Chitetsu, move 63

[Diagram]
 

tderz: B1 is a good empty triangle.
This a game with many local "tenukis" - W6, B7, W8, B9 even in succession ! -
for keeping the initiative.



Example 6 - Taisha

This empty triangle is sometimes played instead of the push at a. See Taisha descent variation.

[Diagram]
Descent Variation  


Acceptable empty triangle? - Hamete

[Diagram]
fighting emty triangle - white's next move?  

tderz: from a Korean book, p.229 (ISBN 89-333-0346-4)
All black moves look completely natural, don't they? (except B5 of course!)
Still he voluntarily created an empty triangle.
Should he have exchanged a for b first?

It's not so easy to decide on white's next move, hence the empty triangle can't be that bad and rather renamed fighting empty triangle.


Fighting empty triangle

Move 81 of the Blood Vomiting Game, diagram 6, move 7 on Senseis' page.

[Diagram]
The third "Ghost" of the "Blood Vomiting Game"  

W7 is the third ghost move. It is an example of a "bad shape/good move", and eventually allows Jowa to launch a difficult splitting attack that results in Black's resignation.


Normal Life & Death

Numerous problems are based on the empty triangle move which kills with a nakade shape. (Therefore it is dangerous to tell beginners that an 'empty triangle is bad'.
One can tell them, that an empty triangle is 'usually inefficient' - but only in the open field.

below from [ext] http://senseis.xmp.net/?KillableEyeShapes:

[Diagram]
Shape #7.2: Three possible patterns for White.  

Number of internal points: 7
Required number of internal White stones to kill: 3
Remaining internal moves to capture: 14
Total internal liberties: 17
Other names: Butterfly Seven

[Diagram]
Shape #7.3  

Number of internal points: 7
Required number of internal White stones to kill: 3
Remaining internal moves to capture: 14
Total internal liberties: 17


[Diagram]
Shape #7.4  

Number of internal points: 7
Required number of internal White stones to kill: 4
Remaining internal moves to capture: 13
Total internal liberties: 17



miaoshou, brilliant, excellent moves

[Diagram]
here the empty triangle is a brilliant move  


Endgame empty triangle

[Diagram]
B2 is the correct local endgame, afaik  

More pro play

Example

This first example, from professional play, offers a surprisingly large number of empty triangles.

brindis: some of these are not good examples; an eye is not counted as an empty triangle. In fact, there is only one thing worst than an empty triangle: filling it with a stone of the same color :-) But if you are forced to convert the inner point of an empty triangle in an eye, just thank your opponent.

[Diagram]
Gu Li (W) - Qiu Jun, 2005 Agon-Kiriyama Cup Final  

The capture of black+circle leaves an empty triangle -- in fact, two empty triangles,-- around the vacated point. Since it is a capture and threatens another capture, it may be a good play, but it does form empty triangles.

[Diagram]
Gu Li (W) - Qiu Jun (ii)  

Next, B2 plays atari, catching the white+circle stones in a connect and die. This illustrates the liberty problem with the empty triangle (too few liberties per stone played). W3 takes black+circle, forming another empty triangle, and B4 takes the white+circle stones, incidentally forming one more empty triangle.

[Diagram]
Gu Li (W) - Qiu Jun (iii)  

Now W5 forces B6, which forms another empty triangle. (At this point, who cares?)

[Diagram]
Gu Li (W) - Qiu Jun (iv)  

A little later W5 cuts, but forms another empty triangle. W7 forces B8, which forms another empty triangle. B10 is atari, but forms yet another empty triangle.

[Diagram]
Gu Li (W) - Qiu Jun (v)  

W1 connects, but forms another empty triangle. Now B2 forces W3, taking advantage of the liberty problem. B4 forces W5, which forms yet another empty triangle. After B6 secures the corner, W7 ensures the capture of the black+circle stones, taking advantage of the liberty problem. Finally, B8 makes an important connection, but forms an empty triangle in the process.

This comedy of empty triangles (11 in 24 moves!) illustrates some of the problems with empty triangles, as well as the professionals' willingness to put up with those problems if the circumstances warrant.


Bob McGuigan: Here's an interesting example from professional play, Ushinohama Satsuo 9p(W) vs. Takemiya Masaki 9p(B), Meijin League, 25 January 1979. The diagram shows the lower half of the board after 86 moves, B1 in the diagram is move 87.

[Diagram]
Ushinohama(W) vs Takemiya(B)  

Ushinohama responded with W2 and Takemiya played B3, a sort of standard good shape move, but in a commentary he criticized B3 as being really bad technique. Ushinohama played W4 and Takemiya played tenuki with a large territorial move in the upper right corner(not shown in this diagram). This allowed Ushinohama to initiate the sequence White b, Black c, White d, which cost Black a lot on the lower side. Takemiya commented that B3 should have been the empty triangle play at a, which would have been good shape in this situation and would not have allowed White to cross under with d.


Good Empty Triangle last edited by 74.136.73.213 on June 27, 2014 - 20:05
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