Gun Six

    Keywords: Life & Death

1. No outside liberties

[Diagram]

Gun six

If there are no outside liberties, this 6 points large eyeshape can be turned into seki. Any of the three marked points accomplishes this result.

[Diagram]

Main line

White makes seki in gote.

[Diagram]

Variation at 1

Starting at 2-2 gives the same result, but ...

[Diagram]

Variation at 2

... starting at 1-2 invites Black to make the mistake of answering at 2-2. White 3 makes a bent four in the corner shape, killing Black.


2. Outside liberties

[Diagram]

Gun six with outside liberty

If there is at least one outside liberty, Black is alive with 5 points.

[Diagram]

Main line

Thanks to the outside liberty, Black can give atari at 4. Without that extra liberty, Black 4 would put himself into atari.


3. Endgame conclusions

[Diagram]

Gun six: endgame

When the last outside liberty is filled, Black 1 makes 5 points in gote (deiri counting).

(As I don't fully grasp miai counting I'd rather have someone else talk about that.)

SAS: Note that 5 points is only correct under Japanese/Korean rules. Under almost any other ruleset the deiri value is only 4 points, since Black would have a point in the seki anyway. As usual for double gote plays, the miai value is half the deiri value (so 2.5 or 2).

The Count: Under area scoring, if Black plays first, he gets all of the "gun six" points (6 more than White). If White plays first, she gets 2, Black gets 2, and 2 do not score (Black and White have the same number). Therefore, the deiri value of a play is 6 points, not 4, and the miai value is 3 points.

Harleqin: You can actually see those three points:

[Diagram]

Gun six: three points

Both white+square change ownership from Black to White, for one point each. Both circle change ownership from Black to neutral, for a half point each.

By the way, every move counts one point more under area scoring - the point it occupies.

The Count: Of course, you're right H, but it is perhaps a bad place to mention it, since in this example Black has an eye in seki and White does not. So under Japanese rules, the miai value of a play isn't 1 point less than 3, rather it's 2.5. Could we just remove the erroneous statement above and say what the miai value of a play is under area scoring, Japanese rules, and territory rules without the special seki rule?


Authors


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