Three Points Without Capturing refers to a corner position that was not played out under traditional territory scoring, but under which one player got three points instead of zero points, which he would have gotten if the position were seki. Under the Japanese '89 rules the position is played out for two points or becomes a ko.
Go rules historian, Chen Zuyuan, claims that the three points rule is derived from stone scoring and is not consistent with territory scoring. He has a point about the derivation. As I understand it, the ruling was be Honinbo Shuwa in the 19th century. Unfortunately, we do not know how Shuwa made his determination. But Chen is wrong about it not being consistent with territory scoring. It is not necessary to invoke stone scoring to derive the three points value. Here I show how to derive it from No Pass Go with Prisoner Return, which has a form of territory scoring.
(;SZ[19]GM[1]CA[ISO8859-1]ST[2]FF[4]AP[GOWrite:2.3.46]GN[ ]AB[bb][ab][ac][bc][ca][da][db][dc]C[Three Points without Capturing under No Pass Go with Prisoner Return.
If this corner is worth three points to White, then if we give Black three White prisoners the result should be zero, i. e., a loss for the second player.
We have to assume no ko threats
]PB[ ]AW[ad][bd][cd][cc][cb][ba]FG[259:]PW[ ]PM[2]
(
;C[Black plays first. If this is a zero, White will win.]B[aa]
;W[ba]
;B[bb]
;W[ab]
;B[aa]
;W[ac]
;B[ba]
;C[Black has 5 prisoners and White has 5 prisoners. Black has to start returning prisoners first and will run out of moves first. White wins.]W[bc]
)
(
;C[White plays first. If this is a zero, Black will win.]W[aa]
;B[bb]
;W[ab]
;B[ac]
;W[bc]
;B[ba]
;W[ab]
;B[aa]
;C[Black has 6 prisoners and White has 5. So White will run out of prisoners first and Black wins.]W[ac]
)
)
I do not want to be drawn into a territory scoring vs. area scoring dispute. Both have their good points. I think that the future lies with some form of Button Go, which synthesizes the two.
