4-5 10-3 enclosure
Keywords: Opening, Joseki
This formation occurred a couple of times in games between Honinbo Retsugen and Sakaguchi Sentoku I (each time the enclosure was Sakaguchi's).
In this case the 3-3 invasion by White gives Black a fair result. But Black at a would already look overconcentrated.
The other direction of extension is rarely used now - White can get a good result invading at
, as you can see by applying the joseki in the previous diagram. In this case
ends up on a silly point.
Go Seigen did try this a couple of times very early in his career.
Coming in at a is asking for trouble with Black b. White would want to live quickly and avoid the trappy variation.
![[Diagram]](../../diagrams/4/b83c45fa7022526389e44a32d720beb5.png)
![[Diagram]](../../diagrams/19/c82024b87e3d9c4b39cb67d8e996f0cc.png)
, having ![[Diagram]](../../diagrams/39/e9eda420e0e2937d75484a42e682c355.png)
![[Diagram]](../../diagrams/14/8ebb796ae72867591d104d5a88f344a8.png)
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