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Countering mirror go
  Difficulty: Beginner   Keywords: Opening, Humour

Mirror go played by White can be countered by Black playing on the tengen, although this is not necessarily the best way. Below shows two examples of countering mirror go. Of course, the result is absurd, but if the player who is mimicking aborts halfway, the other player would have succeeded in stopping the mirror go.

[Diagram]
Countering mirror go (1)

[Diagram]
Countering mirror go (1)

[Diagram]
Countering mirror go (1)


[Diagram]
Countering mirror go (2)

[Diagram]
Countering mirror go (2)

[Diagram]
Countering mirror go (2)

[Diagram]
Countering mirror go (2)

[Diagram]
Countering mirror go (2)



--unkx80


How about this kind of 6-H mirror go ? (Assuming that rules allow Black to place handicap stones where he desires.)

[Diagram]
How to counter mirror go there?

Since there is no komi, the extra moku given by the tengen should give victory to Black. I see no obvious way to counter the symmetry. -- MrKoala


[Diagram]
Countering central-group mirror go

Here we see White beating the above-mentioned mirror go. White 1 captures 36 black stones, but Black 2 does not capture the corresponding white stones, because they have gained two liberties through White's capture - Andre Engels

Thanks a lot, Andre Engels. I think it could also be applied to the tengen-as-first-move mirror go, couldn't it ? -- MrKoala

SAS: There seems to be a practical problem with the method shown above for countering the 6-stone handicap mane-go. If Black stops mimicking as soon as White plays on the first line, then White's position is pretty bad --- even allowing for the 6-stone difference in stength I think it may be difficult for White to win in the face of Black's huge moyo.


rubilia: The capturing ring doesn't have to crawl along the border, it can also be settled some points closer to the center:

[Diagram]
counter mirroring by ring capture

[Diagram]
the same, even closer to the center



But, still, these situations are highly artificial.


Here's another standard anti-mane-go strategy that can be used instead. It assumes that some form of superko rule is in force. White starts by creating two kos; call these kos A and B, and their mirror images A' and B'. White captures in A, and Black mimics by capturing in A'. Then White captures in B, and Black captures in B'. Then White recaptures in A', and Black recaptures in A. Then White recaptures in B'. The superko rule forbids Black from recapturing in B, so he has to stop mimicking.

rubilia: Nice! This sounds much more likely to be usable. It's not too hard to set up a few big kos, even without providing "weak" moves which could make the opponent stop mirroring.



This is a copy of the living page "Countering mirror go" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.