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DoubleSente

 

Sente Sente
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A local position is said to be sente-sente (or double sente) if a play by either side would be sente.

[Diagram]
Diag.: Sente-sente position

The simplest sente-sente position is on the left. White can play 1 and 3 in sente. Compared to a black play (Black 1 at 3 etc.), white has two more points of territory, whereas black has 2 less., i.e. a total of 4 points. Using miai counting, this is said to be a four point sente play for both sides.

Comment: Actually, that's by deiri counting. The miai value of a double sente is a relatively large number. -- BillSpight

Double sente plays should normally be played whenever the value of the play is larger than other moves on the board. Since a double sente play is first-come first serve, they are often played earlier than that, if the sente 'threat' is large enough. (E.g. in this case, if black does not answer at 2, white can take a large chuck out of blacks territory, so this may well be played before the 4-point value would normally indicate.

-- MortenPahle



BillSpight:

Double sente is a relative term; i. e., it depends on the rest of the board. Every go position can be categorized as sente, gote, or ambiguous. Its environment determines whether each player can play in it with sente, if ever (assuming correct play).

Example (outer stones alive):

[Diagram]
Diag.: "Double" sente

This appears in Kano's Yose Dictionary. He says that it is a double sente, but that Black's play has more "necessity". (It threatens White's group.)



Actually, this is a 7 point sente for Black. If Black plays first, we get

[Diagram]
Diag.: Black sente

which has a local score of 5.



If White plays first, we get

[Diagram]
Diag.: White reverse sente

which has a local count of -2 (2 points for White).



Later this is White's sente.

[Diagram]
Diag.: White sente


And even later, this is Black's sente.

[Diagram]
Diag.: Black sente (2)

The local score is -2.



After White's hane, Black's reverse sente is worth 3 points.

[Diagram]
Diag.: Black reverse sente

The local score is 1.

The original position is a 7 point sente for Black. However, when the ambient temperature drops below 3 points, it is double sente (as a rule).





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