See Miai Values List for conventions and explanation.
Initial count: 0
The 1/2-point button is used in some rulesets that try to form a compromise between area scoring and territory scoring. E.g., instead of playing or passing a player may take the one and only 1/2-point button (by area scoring).
The miai value by area scoring is 1/2 because if Black spends one move, he gets 1/2, while if White spends one move, he gets -1/2. The calculation is: (1/2 - (-1/2)) / 2 = 1/2.
To convert from area to territory scoring we subtract 1 point, yielding -0.5.
Bill: Note: Buttons are not used or contemplated with territory scoring. Button go may be seen as a compromise between territory and area scoring.
There are other types of neutral (dame) points including: protective moves (teire) against the cut when outside liberties are filled; capturing stones in seki, etc.
Connect ko
Initial count: -0.33
White has 1/3 point equity in the stone. We may think of it as 1/3 captured.
Take ko
HolIgor: This move together with the one above should give a point, shouldn't it?
Bill: Yes, but Black started with 1/3 point net equity , so each move gains 1/3 point, on average. :-)
See half-point ko.
Initial count: -2.5
After the corner is worth -2. White has captured 3 Black stones, but Black can claim the
stone.
(Note: If White is komaster she can make ko to protect , but Black gets 3 moves elsewhere.)
Now there is a 0.5 point play at a.
The swing is 1 point at plus 0.5 - 0.33 = 0.17 in the corner in gote. That yields a miai value of 0.58.
Defend potential point, set up 0.67 position
The initial position has a local count of 2 5/6. The result after has a local count of 3 2/3.
gains 5/6 of a point.
Take away potential point (corridor)
Take away potential point (corridor)
For higher values see /1.00 to 1.99, /2.00 and more.
[3] Bill, now I'm confused - I think. Black's sente - I've switched the colours for ,
. OK, so using miai values means sequences don't need to be flagged as such (sente, or gote). Ah, I get it: White connecting on either side leaves
where Black has in effect 0.33.
Leaving this comment for others' benefit. Charles
Bill: This is an ambiguous position. Its miai value is 1/3, but Black can take one stone and threaten to connect with sente. Then, OC, the position still has a miai value of 1/3, and Black's sente has gained nothing locally. (It may have been a ko threat.) In thermographic terms, it has a blue mast up to temperature 1 2/3.