Cutting the Keima

  Difficulty: Beginner   Keywords: Shape, Tactics


Reference diagram  

This is a keima. It can be cut at a or b

Do not cut without support

Cutting a keima  

Cutting the keima without support will usually strengthen the opponent.

After the cut with B1 and B3, White has extended from a crosscut and sente which is very advantageous for him. Next, W4 may capture the cutting stone in a ladder

So, cutting a keima is only advised when the attacker has support from other stones.

A genuine cut


When black+circle is present, the cut becomes more severe. If the ladder at a works for Black, B1 is a genuine cut.

Striking at the waist of the keima is usually the correct way to cut. We refer to that page to understand why that is so.

Very severe  

If on top of black+circle, there is also a black stone black+square, the same sequence results in a very severe cut.

Diagonal cut

Cut diagonally  

When cutting the keima is strategically important, this diagonal cut (kosumigiri) is sometimes used mainly if a) the ladder is bad for Black, or b) Black has another stone at x, avoiding an empty triangle. This gives White more forcing move possibilities ( a to d ) than the genuine cut above.

Comparing to the one space jump

No effective cut  

If we compare the genuine cut above with this one, where Black tries to cut a one space jump, we can see that White is reinforced and black+circle weakened, even if Black can next continue to cut at a. We can say Black has effectively cut himself here rather than White.

OC, that is ridiculous, since there was no Black to get cut to start with.

These diagrams show why, in hostile environment, the more stable one space jump is preferable for defending, whereas a keima is often more appropriate for attacking purposes in friendly environment.

Would that things were so simple!

Further reading

Cutting the Keima last edited by 2620:0046:8000:0076 on January 10, 2023 - 23:16
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