Points Rating System
"Points Rating System" (Tensuusei 点数制) is a rating/handicapping method used among the amateur Go clubs in Japan.
It is used so that the win/loss result of a game will add 1 point to the winner's rating, and subtract 1 point from the points of the loser.
Below table is used to determine the number of handicap stones and Komi for the game.
- Lookup the points difference between the White and the Black players on the above table. If one player's rating is 130, and another's is 110, the higher ranked player will take White, and the points difference will be 20. Find 20 on the above table. Look to the right-most column to find 1, which is the number of handicap stone(s) placed by Black for the game. Look to the bottom row to find -2, which is the Komi given to Black as the player of the first move. The positive Komi figures indicate Komi given to White (the second mover).
- In the case of a tie, White wins (the same effect as adding 0.5 to Komi).
1. Games with the same opponent is counted up to 3 games in a given day.
2. Points for the players in those games with same opponent do not change during the day. (If the result is 2-1 for White, the difference of 1 point is given to the White player rating, 1 point is subtracted from Black player's at the end of the day.)
3. Komi is given at the beginning of a game in the form of stones to the recipient's prisoner tray.
Initial points assignment according to the existing kyu/dan.
|Initial Points Assignment|
The above table is an arbitrary method to bring new players onto the points rating system, and is just an example used by a regional branch of Nihon Kiin (Tagajo Branch, Nihon Kiin 日本棋院多賀城支部) It is for the trial adaptation of Points System by the branch, and does not imply endorsement by Nihon Kiin.
The initial points assignment needs to be modified and adopted to each club or server in accordance to their assessment on the relative strength of the ranking. It is theoretically OK to use negative rating for lower kyu's below 10k, but the 12 points spacing among the ranks should be retained if 1 kyu difference is meant to represent 1 handicap stone. Note that the above initial assignment table is based on the notoriously inflated kyu/dan rankings existing in Japan as of 2015. See Rank - worldwide comparison for reference.
The Points Rating System was invented by Yasuro Kikuchi, Headmaster of Ryokusei Igo Academy ( Ryokusei Igo Gakuen 緑星囲碁学園) in the 1980's. Sometimes known as Ryokusei Kai Method (緑星会方式), it was adopted by many Go clubs and salons in Japan, as inflation and regional disparity problems of Nihon Kiin kyu/dan rankings became acute in the 1990's and the 2000's.
Concept and the Current Status
The above table is based on 6.5 point Komi as the base and the concept "Komi is given to White to offset Black's first-mover advantage. The value of this offset is half of the value of first move, so when 6 point Komi is presumed correct, 12 points is also assumed correct as the value of first move" (+0.5 is just another way of specifying "White wins in a tie")
In the late 1990's, statistics on the use of above table revealed that the table gives advantage to White. This is because the value of first move is much less for amateurs than for pros(where 6 points Komi is appropriate) and clubs and salons started modifying the table.
See Point Ranking Scheme At Tokyo Go clubs for one example of the modification with less than 12 points for 1 stone disparity (figures with one row difference in the above table). Although this particular modification is theoretically inconsistent in the use of 6.5 point Komi as the basis and less than 12 points one stone disparity, it is generally accepted now that less than 12 points is more appropriate for amateurs. The base-Komi is supposed to be adjusted to be half of this "less than 12" figure in theory, however, keeping the base at 6.5 in accordance to Nihon Kiin (pro) rules is common.
Reverse Komi Table is a method in which the varying value of first move is fully incorporated according to the strength levels. -