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Real Half Point Ko
Keywords: Ko
This ko, commonly known as a half point ko, has a miai value of only 1/3.
However, this ko really does have a miai value of 1/2. :-)
W 2 elsewhere, B 3 fills.
Result: 0. A difference of 2 moves makes a difference of 1 point, so the miai value of the ko is 1/2.
W 3 - B 4 = ko threat and reply. W 5 takes ko back. B 6 elsewhere. W 7 at 2. Result: -1.
W 2 elsewhere. W 4 - B 5 = ko threat and reply. W 6 takes ko back. B 7 elsewhere. W 8 at 3.
Result: 0.
Again, a difference of 2 plays makes a difference of 1 point. Miai value of ko = 1/2. When Black is komaster the ko has a miai value of 7/12.
W 1 fills, leaving a 1/2 point play at a.
W 4 takes ko. B 5 - W 6 = ko threat and reply. B 7 at 1.
Result: +2/3. (Black has taken 1 stone for 1 point, minus 1/3 point for the Black stone in ko.)
After B 1 the local temperature drops to 1/3. Black has a sente sequence with B 3 - W 8.
2 plays make a difference of 1/2 + 2/3 = 7/6 points. The miai value of the ko is 7/12. -- Bill Spight This is a copy of the living page "Real Half Point Ko" at Sensei's Library. (C) the Authors, published under the OpenContent License V1.0. |