Shoulder invasion of mixed three space extension

    Keywords: MiddleGame, Joseki
[Diagram]

Not an invasion

The shoulder move W1 is one of the more common moves against a mixed three space extension, Black a, b or tenuki is to be expected.

In practice it is played as ladder breaker, actual or preemptive, as reduction, as focal play in the context of larger frameworks, as a forcing exchange to strengthen a weak group on the outside, or in a fashion similar to a leaning attack.

[Diagram]

Alternatives as reduction

If intended as a reduction White moves at c or d, which are commonly answered at e and f, respectively, are more often seen than the shoulder hit.

Some possible sequences

[Diagram]

Black connects

[Diagram]

Similar to a shoulder hit on an unsupported stone

Slarty: on an open board, Black can probably be pleased to answer W1 at B2. It's then not possible to separate the black stones without acquiring a heavy shape. Not sure if there is a SL page for normal shoulder hit side josekis.

tapir: Well. This is practically never played on open boards, hence midgame. If separating is the main intention I wouldn't start with W1, which offers Black options to connect. In this variation if Black does not connect, White has an option to separate, that does not need belittling. White at a later does not look like bad shape to me. (Transposition of a midgame joseki when Black invades White, afaik.) Finally, SL coverage of midgame joseki is pretty bad. Reduction techniques was a good start for reductions, but the individual pages are lacking content.

Slarty: It's true if W3 somehow gets Black to play elsewhere, W has an option to cut. Probably the point to the left of a. If a, B can respond at the point to the right of a.

[Diagram]

Quite possible

[Diagram]

Quite possible II

[Diagram]

Admission

When Black can't afford being cut off from a weak group in the center B4 might be necessary, which allows White to break in after e.g. W5 at a.


Ladder breaker

[Diagram]

Jiang Weijie (B) vs Won Seong Jin - Chunlan Cup - 2012-12-04

[Diagram]

Jiang Weijie (B) vs Won Seong Jin - Chunlan Cup - 2012-12-04


Framework building

[Diagram]

Takemiya Masaki (B) vs. Takao Shinji - 24th Tengen - 1998-07-09

This framework building was followed by an invasion at a.


Reduction

[Diagram]

Cho Hun-hyeon (B) vs. Yi Ch'ang-ho - 38th Kuksu - 1994-09-24

While it is a reduction at this point, when Black returns later to a White does not answer and it turns into an invasion only after Black b followed by White c. The invasion is sacrificed in the course of fighting for the White center group.


This is a copy of the living page "Shoulder invasion of mixed three space extension" at Sensei's Library.
(OC) 2016 the Authors, published under the OpenContent License V1.0.
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