4435 enclosure

    Keywords: Opening, MiddleGame, Joseki

[1]

[Diagram]

4435 enclosure

The assumption is that this is made from the initial 4-4 point.

[Diagram]

reduction sequence


This is a standard way to reduce a framework based on 4435. The 3/4 exchange may sometimes be omitted.


[Diagram]

From the 3453

Starting from the 3453 enclosure, B2 after W1, rather than Black a, is possibly too steady (though one can hardly call it a mistake - it's one possible answer to this as middlegame joseki). This accounts for White's willingness to force Black in the reduction sequence.


[Diagram]

Early endgame sequence



The 3-3 invasion in this position cannot live, but may be useful in other ways. Sometimes it can function as a probe. Here it gives White a big endgame play at 3. Black needs another move at a to secure the corner, so this should be played in the early endgame, when it ought to be sente.

[Diagram]

Life

If Black reacts on the other side to the marked play, White gains life in the corner.


How should you kill the 3-3 invasion?

[Diagram]

3-3 Invasion

Like this?

[Diagram]

3-3 Invasion countermeasure 1

After B10, there is no escape

tapir: A white stone at a threatens to connect out, since black+circle is most often played as answer to a white stone at a one has to remember this potential.

[Diagram]

3-3 Invasion countermeasure 2

After B10, a and b are miai for black. Note, however, that if white can play the hane at c in sente then white can live after that with b.

White can also choose to play W7 outward at B8, allowing black to cut. That way, white will lose the corner, but may live along the left side.

[Diagram]

3-3 Invasion

tapir: White is alive after W5, B4 is bad.


[2]

This formation may arise from the 4435 enclosure, usually with at least one white stone at a or b. It is known as the Three Crows.

[Diagram]

3-3 invasion

Even with both white+circle stones in place, the invasion at W1 need not succeed. B4 is something of a concession (see two diagrams above for the reason, in a related case), but the corner is then safe enough.

With just white+circle in place, Black can try B2 (or Black at a) in reply to W1. The feeling is then to avoid being forced, and make W1 into mochikomi.



That is at the cost of some bad aji here for Black. In pro games W1 can be played as a probe.

Charles Matthews


This is a copy of the living page "4435 enclosure" at Sensei's Library.
(OC) 2011 the Authors, published under the OpenContent License V1.0.
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