TFG9 White at the Top

    Keywords: Life & Death

Remember, here we are concentrating on the situation of the White group in the center top, ignoring for the moment the state of the black stones to the left.

[Diagram]

Black plays first

(White 2,4,6 elsewhere)

As noted elsewhere, if Black plays first, White has four liberties. This means that if Black could make four liberties on the left in sente, Black could start here and capture White - in theory.

What it really means is that if Black makes five liberties on the left, White can't afford to continue there and is forced to come back to the center top and play there. What happens if White does?


[Diagram]

White plays first 1a



[Diagram]

White plays first 1b

If White tries W5 here, extending the liberties of the cutting stone, B stops White cold with B6, reducing White to two liberties (either of the points a next puts White in atari).

From this it is clear that W1 above does not help White. What next?

[Diagram]

White plays first 2a


Note that this case raises the important question of what happens if both sides live. Assuming that White came back to the center after not being able to capture Black on the left, who wins the game if Black lives on the left while White lives in the center?

But is this the best that Black can do?

[Diagram]

White plays first 2b

(2 elsewhere) The count is B + 2, W - 1 = Net +1

[Diagram]

W's internal liberties 2

(2, 4 elsewhere) The count is B + 3, W -1 = Net +2 with +1 in the previous diagram so total Net +3

[Diagram]

W's internal liberties 3

(2, 4 elsewhere) Final count is +3 here with +3 in the previous diagrams for a total of six internal plays required for Black to capture White.

[Diagram]

White plays first 2c

Note that Black can't switch B4 in diagram 2b to here. White has an outside liberty at a, and can throw in at W5 and after Black captures at B6, White traps two black stones with W7.

Oops!!!! This is not correct. When Black plays W5, White will not capture at 6 but instead will extend at W7. After White b, Black c it is ko but White has fewer liberties than in 2b (total of five?). This changes the conclusions below. I'll have to revise them later. -- Dave


So at this point White has only one eye at the top but has expanded from four liberties to eight liberties in gote, if Black plays next on the left; or seven in sente (if Black plays next at the top and lets White play next on the left). What does this mean for the status of the black stones on the left? Remember that White played tenuki on the left in order to play at the top.


This is a copy of the living page "TFG9 White at the Top" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.
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