HalfPointKo/WME

Sub-page of HalfPointKo

Chinese: 半劫 (ban4 jie2); 单劫 (dan jie2);
Japanese: 半コウ (hankou); 半劫 (hankou)
Korean:

A half-point ko is the common term for a ko in which nothing is at stake beyond the fate of the stone inside the ko.

[Diagram]

"Half point" ko



Often go games end with a fight over such a ko. (These fights are not shown in professional game records, as a rule. Instead the winner is indicated.) It is rare to have a play smaller than this but larger than a Japanese dame.


Bob Myers: What play could be smaller?

Bill: Depending upon komaster, there are kos worth 1/4 and 1/5 point. I constructed the 1/5 point ko; 1/4 point kos show up occasionally in real games but are unrecognized as such.

Bob Myers: Where are these documented?

Bill: I misspoke. There are 1/4 point ko positions. (By the time a ko has appeared, the ko is hotter.) Here is an example, with Black komaster.

[Diagram]

1/4 point reverse sente

B5 - W6 = threat and reply

B7 takes ko

W8 elsewhere

W10 takes ko

[Diagram]

1/4 point reverse sente (cont.)

B1 - W2 = threat and reply

W4 elsewhere

W6 takes ko

B7 - W8 = threat and reply

B9 takes ko

W10 elsewhere

B11 fills ko (white+circle)

W12 elsewhere

Black has gained 1 point with 4 net local plays, each worth, on average 1/4 point.


Despite the name, the miai value of connecting or capturing in a half-point ko is only one third of a point. But if we do not know the winner of the ko fight, who gets the point at stake is a 50-50 proposition, and the term makes sense.

See /Calculation? for determining the value of this ko.

See /Name? for suggestions for naming this ko.

See also Real Half Point Ko



This is a copy of the living page "HalfPointKo/WME" at Sensei's Library.
(OC) 2009 the Authors, published under the OpenContent License V1.0.
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