Good Empty Triangle

    Keywords: Shape

Table of contents Table of diagrams
Joseki (a)
Related joseki
Mutual good shape
Joseki (b)
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

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

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.

Good empty triangles

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.

[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 (b)

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.)

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.


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.



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


This is a copy of the living page "Good Empty Triangle" at Sensei's Library.
(OC) 2011 the Authors, published under the OpenContent License V1.0.
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