Countering Mirror Go 2

    Keywords: Strategy

It has been suggested that the content of this page should be merged with mirror go.


This page is intended as a more serious counterpart to the Countering Mirror Go page.

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Example 1

anonymous: The first mistake is to be unaware that manego is possible. In Example 1, it is to early to tell if black is playing mirror go, but white's moves make mirror go a viable strategy. Black's three stones are working together nicely and no matter where white plays black's moyo will be larger because of the tengen stone. This is not just a poor refutation of manego, it's poor go.

xela: It doesn't look like poor go to me, it looks quite good for white. B1 contributes less to black's moyo than either a or b would; white has komi and sente. I just did a search and found nine pro games with this exact position. White won eight out of nine, and seven of those were without komi. The most recent game I found was from 1985. Since then, the pros seems to have decided that this is not a viable strategy for black. (If you delete B1 from the board and look at it as black to play, it's quite a common position--and people don't often play tengen here.)

Warfreak2: My thinking here is that a and b are miai: yes, black would like one of them to make a loose box-like moyo, but white cannot stop him getting one. It's the go-ren-sei fuseki without the exchange of a for b. Not that this makes it good for black, but it should be perfectly playable.

[Diagram]

Example 2

anonymous: The second mistake is to play an irrational move in an attempt to capture black in a cheap trick. In Example 2, white notices black's mirror go when black plays B9. White plays W10 in an attempt to begin a capturing race in which B1 is a burden to black. However, when black breaks mirror go by extending to a, white has no good local response, and has suffered a loss in the center by strengthening black. Ladder strategies against the tengen stone share much of the same bad taste.

Looks playable to me. Sure, black will be slightly stronger than white, but white can answer a with b or answer hane with crosscut and still have pretty good chances (crosscut is probably more common than a in professional play). ~srn347

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Example 3

anonymous: Proper strategy is to recognize the possibility of mirror go from the start and play a solid territorial game in which black's tengen stone feels inconsistent and does not aid black in fighting or building a moyo. In Example 3, white plays a solid territorial game that would feel like relying on komi even if black were not playing manego. While B9 is a natural move, B1 makes W8 feel like a light refutation of ippoji. Black has played a territorial game that is inconsistent with his first move and has lost most of its advantage.

xela: What if white plays W2 and then black decides not to play mirror go? Many people would prefer to have W2 on the 4-4 or 4-5 point.


xela: I wasn't aware of the existence of a generally accepted "proper strategy" against mirror go. Can you give a reference for this information?


This is a copy of the living page "Countering Mirror Go 2" at Sensei's Library.
(OC) 2011 the Authors, published under the OpenContent License V1.0.
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