PlayingAProGameBackwardsGame1/Right side

Table of contents Table of diagrams
3/4 point play
3/4 point play, Black first
3/4 point play, White first
Hanami ko
Curious sequence
Goodbye, eye

3/4 point play

[Diagram]

3/4 point play

Bill: After B1 - W2 (not played in the game), there is a 3/4 point play (miai value) in the marked region.

[Diagram]

3/4 point play, Black first

After B1 - B5 Black has 1 point (circle).

[Diagram]

3/4 point play, White first

After W1 White has 1 point at circle, and Black has 1/2 point at square. (Black can play black+circle - white+circle in sente.) The local count is -1/2.

In the disputed area the original local count is 1/4. Either player can gain 3/4 point in one net gote play.

[Diagram]

Hanami ko

The evaluation above depends upon White's not playing W1 - W3 in this diagram. If White does so Black can start a hanami ko with B4. In the game the black+circle - white+circle exchanges were made at the 1 point level. Since this is a hanami ko, White needs larger ko threats than Black. White has 3 large ko threats at and around z on the bottom. (I don't think the threat at y is quite large enough.) Black has ko threats at a, b, and c, and 4 threats at and around d, for 7 threats, 3 or 4 threats more than White. White should avoid the hanami ko, even though he takes first.

Curious sequence

[Diagram]

Curious sequence

Bill: Instead of taking his 1 point sente at a, Black played the 3/4 point play, B1 - B5. Then instead of playing the 1 point reverse sente at a (or another 1 point play), White filled with W6, leaving Black with 1/2 point of territory at circle. How come?



[Diagram]

Goodbye, eye

B6 at B4. W7 at B2.

Bill: If White does play W1, Black can reply with B2 - W7, taking away White's eye on the edge. Later White must make a protective play at circle.

However, White must protect at circle anyway. After the protective play at square, the White stones to the left will still have only one liberty when all the dame are filled, obliging White to protect at circle. Black gains nothing by taking away the eye.

Did both players, who are obviously strong, made technically inferior plays on the right side. Did they both have the same blind spot about circle?

Let me speculate. I think that both players had already read to the end of the game. White knew that he was going to get the play at a, anyway. In that case, why not preserve the eye? It might not help, but it couldn't hurt. As for Black, all other reasonable variations left White with the eye. If White protected the eye, as in the game, no harm done. If not, I don't know.... Black could fall into a trap if White plays elsewhere.



This is a copy of the living page "PlayingAProGameBackwardsGame1/Right side" at Sensei's Library.
(OC) 2014 the Authors, published under the OpenContent License V1.0.
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