Oteai

The Oteai (大手合) was a tournament used by Nihon Ki-in and Kansai Ki-in in 1927-2003 (resp. 2004) to determine the dan rank of their members. Players were 1-dan to 8-dan professionals who could earn a promotion by getting a large enough point average in a series of consecutive Oteai games. Games were played without komi, but a win with White gave more points than a win with Black, and a win against a strong opponent gave more points than a win against a weak opponent.

Games

More than 7000 games are available in the current directory, but only some from the years 1934, 1967, 1968, 1969, 1970, 1972, 1974, and 1976 are linked to.

Points

The details have varied over time. Around 1970 the Nihon Ki-in rules were as follows:

Each year, 1-3 dans play (at most) 12 times, 4-dans 10 times, 5-8 dans 8 times (and 9-dans do not participate since they cannot be promoted any further).

The players are divided in two groups: 1-4 dans and 5-8 dans, so that the rank difference in a group is at most 3. A player of rank r earns points as follows:

opponent
rank color win jigo loss

r B 75 45 15

r W 105 75 45

r+1 B 80 50 20

r+1 W 110 80 50

r−1 B 70 40 10

r−1 W 100 70 40
r+2 B 90 60 30

r−2 W 90 60 30

r+3 B 100 70 40

r−3 W 80 50 20

opponent rank	color	win	jigo	loss
r	B	75	45	15
r	W	105	75	45
r+1	B	80	50	20
r+1	W	110	80	50
r−1	B	70	40	10
r−1	W	100	70	40
r+2	B	90	60	30
r−2	W	90	60	30
r+3	B	100	70	40
r−3	W	80	50	20

When the random draw of opponent pairs selects a pair of players, they play each other in three successive years. Such a series of three games is aborted if one of the players is promoted. The handicap depends on the rank difference.

rank
difference handicap color

0 tagaisen players alternate in color

1 sen-ai-sen the weaker player has Black twice and White once

2 sen the weaker player always has Black

3 senban the weaker player always has Black

rank difference	handicap	color
0	tagaisen	players alternate in color
1	sen-ai-sen	the weaker player has Black twice and White once
2	sen	the weaker player always has Black
3	senban	the weaker player always has Black

In earlier times the handicap for a rank difference 3 was sen-ni-sen: the weaker player got a 2-stone handicap one out of three games. The above table was extended by two lines for the case a 2-stone handicap was received or given.

opponent
rank color win jigo loss

r+3 B 70 40 10

r−3 W 110 80 50

opponent rank	color	win	jigo	loss
r+3	B	70	40	10
r−3	W	110	80	50

As can be seen from the above tables, each game has a total value of 120 points, shared between winner and loser. If a player has a sufficiently high point average over a sufficiently long series of games, he can claim promotion. The player can choose the start and length of the series.

minimum game series length

point average

rank 75 70 67.5

1-dan 8 12 16

2-dan 10 14 18

3-dan 12 16 20

4-dan 14 18 22

5-dan 16 20 24

6-dan 18 22 26

7-dan 20 24 28

8-dan 22 26 30

minimum game series length
	point average
rank	75	70	67.5
1-dan	8	12	16
2-dan	10	14	18
3-dan	12	16	20
4-dan	14	18	22
5-dan	16	20	24
6-dan	18	22	26
7-dan	20	24	28
8-dan	22	26	30

Comments for 1968

Looking at the 1968 games, we note several games between low-dans and high-dans. Also, a game between Nabeshima Ichiro (7p) and Kano Yoshinori (9p) shortly after the latter was promoted to 9-dan. The rank difference is at most 2, except in the games between Fukui Susumu (3p) and Kobayashi Reiko (6p), and between Tsuchida Masamitsu (5p) and Ishii Kunio (8p), but both Kobayashi Reiko and Ishii Kunio were promoted earlier in 1968, so probably these games had been scheduled before the promotion.