Ko Lock
Difficulty: Advanced Keywords: Tesuji, Shape, Tactics
![[Diagram]](../../diagrams/24/a9171dcaea5d7a5ebdfb8e0a59e072e1.png) | After the cross-cut |
For White to play in reply to Black's cut here is a standard piece of shape. White has a good reply to Black a atari.
![[Diagram]](../../diagrams/12/96be23375461b628c6d9de81183101df.png) | Ko lock (i) |
If , is double atari and is forced.
![[Diagram]](../../diagrams/5/31ffb4a95fe9532cd1b30990d45065a6.png) | Ko lock (ii) |
White plays relying on being able to capture at a in sente, forcing Black b. Since there are proverbially no ko threats in the opening, White's plan will very often work and build influence.
![[Diagram]](../../diagrams/31/3d935c955146ad32c1c284a58b3ae907.png) | After the cross-cut |
Therefore Black usually[1] extends to (or a - the choice isn't straightforward): next leaves White's marked stone on a good point for shape.
This tactic is as old as the hills; but the 'ko lock' name goes back to Victor Chow, a Chinese amateur now in South Africa.
Charles Matthews
[1] Actually it seems that the atari is also current in pro games, while the extension to a isn't.
This is a copy of the living page
"Ko Lock" at
Sensei's Library.
2004 the Authors, published under the OpenContent License V1.0.
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