Point Ranking Scheme At Tokyo Go clubs

DaveSigaty: In my experience quite a few Go clubs in Tokyo use a similar point scoring system to decide komi and handicap. Each person at the club has a card for keeping track of their results. A win adds 1 point to the score on the card while a loss subtracts 1 point. Scores are adjusted after each game. When two players sit down to play they compare their scores and look up the difference in scores on a table printed on the back of the card. For each 1 point difference in scores the komi is changed by 1 point. If the difference is large enough, extra handicap stones are included as well. In the past the most common table was based on 15 points per handicap stone. The table looked something like this:

 Point  Handicap         Point  Handicap         Point  Handicap
 Diff.  Stones   Komi    Diff.  Stones   Komi    Diff.  Stones   Komi
  0        0      6.5    15        2      6.5    30        3      6.5
  1        1      5.5    16        2      5.5    31        3      5.5
  2        1      4.5    17        2      4.5    32        3      4.5
  3        1      3.5    18        2      3.5    33        3      3.5
  4        1      2.5    19        2      2.5    34        3      2.5
  5        1      1.5    20        2      1.5    35        3      1.5
  6        1      0.5    21        2      0.5    36        3      0.5
  7        1     -0.5    22        2     -0.5    37        3     -0.5
  8        1     -1.5    23        2     -1.5    38        3     -1.5
  9        1     -2.5    24        2     -2.5    39        3     -2.5
 10        1     -3.5    25        2     -3.5    40        3     -3.5
 11        1     -4.5    26        2     -4.5    41        3     -4.5
 12        1     -5.5    27        2     -5.5    42        3     -5.5
 13        1     -6.5    28        2     -6.5    43        3     -6.5
 14        1     -7.5    29        2     -7.5    44        3     -7.5

• Point difference 0 = Black player decided by nigiri
• Handicap 1 = Black (moving first)
• Negative komi = White gives, Black receives

So when a player with 215 points is matched against a player with 238 they compare cards, calculate the point difference as 23 and check the table. The table shows that the correct handicap is two stones with White giving a 1.5 point komi. If Black wins the first game, Black gains 1 point and White loses 1 point on their cards. As a result, the point difference for the second game falls to 21 points. The table shows that the correct handicap is now 2 stones with black giving 0.5 point komi. And so it goes...

In 2001 the Takadanobaba Go Club, where I used to play fairly frequently, shifted to an 18-point scale. At the same time they eliminated fractional komi so that jigo may occur. The komi ranges from Black giving 7 when the point difference is 0 (or 18, 36, 54, etc.) to White giving 10 when the point difference is 17 (or 35, 53, etc.).

See Points Rating System for a more generic system description, and historical background.