Komidashi
From Wikipedia, the free encyclopedia
Komi points are points given in the game of go to one player to add to his score as compensation for playing as White. Komidashi is the more complete Japanese language term. Komi is known as Ho-Sun 호선 in Korean.
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[edit] Whole number and halves
Conventional komi in most competitions is a half-integer such as 6.5 points. This is convenient and the prevailing usage for tournaments, since it rules out a tied game (jigo in Japanese) and rematches. In a club or friendly game this is not a problem, so a value such as 6 points is just as practical. Within a Swiss system draw, tied games are not inconvenient and tiebreakers are used.
Some argue there is nothing wrong in having a tie. Forbidding a draw may misrepresent one player as superior when there is no clear difference in skill. There is however a hidden parity question which means that a draw may be unlikely. Lately, the Ing Cup has been using an 8 point komi rule in their tournament, but with the rule that if the scores are equal after komi then Black wins, so this is equivalent to 7.5 points.
[edit] History
White is at a disadvantage due to the fact that Black gets to move first, giving that player sente. Records show that the winning percentage of Black is higher. The importance of playing first was however not dealt with by rule, until the 1930s, and only then tentatively.
The compensation (komi) system was introduced into professional go in Japan as a gradual process of innovation, beginning in the 1930s. The correct value of komi has been re-evaluated over the years, as professional opening strategy has evolved.
At first, komi started as low as 2.5 points or 3 points. It was later increased to 4.5, and then 5.5 points. 5.5 points was used for a long time, but research found that 5.5 points was insufficient to compensate for White's disadvantage. Statistical analyses of the year's games would sometimes appear in the Igo Nenkan (Kido Yearbook), backing up the impressionistic feeling of many top players. The use of databases confirmed figures such as 53% victories for Black, not just at the highest level.
Komi was then raised to 6.5. Some events use as high as 7.5 points. Under the Chinese method of counting, the difference between 6.5 and 7.5 point is of minimal effect. (Chinese sources usually in fact quote figures that are halved, such as 2.75 for 5.5, at least for Chinese domestic competitions.)
John Fairbairn, a Go historian, has written on the History of Komi.
[edit] Effects on strategy
Since very minor mistakes can cost one point, discussion of the 'true' value for komi makes little sense, except at the level of the top-ranked players in the world. These are (in most cases) also the opening-theory experts, and evaluate opening strategies in practical play against their peers.
The introduction and then increase of komi has led to ever more ambitious or aggressive strategies for Black, the first player. In the days before komi, White as second player had to disrupt the smooth working of Black's classical strategies, described sometimes as aiming for a sure win by 3 points. From the introduction of komi in most pro events, around 1950, Black's older methods had to be reconsidered, since White suddenly needed appreciably less (in pro terms) in secure area. The 3-3 point became an interesting play for White, where previously it appeared experimental, and was developed in particular by Go Seigen and Sakata Eio.
In the following decades a mixture of classical and shinfuseki techniques became normal. The most obvious effect was the replacement of the 4-3 point by the 4-4 point as the most common way to first occupy a corner.
[edit] Fairness of compensation points
It is a hard theoretical problem to determine the best and fairest value of compensation points, because it can be taken to ask for the result of a game of go with best play by both sides. It can be estimated that playing first is equal to about half a move (or a bit more) ahead throughout the game.
[edit] Local variations
Although the generally acceptable compensation points nowadays are 6.5 points; each country, association, and tournament may set its own specific compensation points:
- In Japan, the usual komi in Japan was once started at about 2.5 points. For some time later, it is raised to 4.5 points. In 1955 the Oza became the first tournament to adopt 5.5. The value of 5.5 became standard over some decades. The Nihon Ki-in decided to change to 6.5 in September 2002.
- In Korea, it used to be 5.5, but is switched to 6.5 now.
- In China, the usual compensation point was 5.5, but 7.5 is now standard. 6.5 would have had a minimal effect due to China's use of Chinese scoring rules.
- In America, American Go association (AGA) official rules used to specify 5.5 points, however they later suggested also experimenting with values up to 8.5 points in both informal games and tournaments in order to gather data to determine the effects of increasing U.S. komi officially. The American Go Association changed komi from 5.5 to 7.5 in August 2004, effective 2005.
- The New Zealand rules specify a komi of 7.
- For Ing Foundation, the Ing rules also have a compensation point of 7.5, specified as 8 points with Black winning draw.
[edit] Type of compensation system
[edit] Fixed compensation point system
By far the most common type of komi is fixed compensation point system. A fixed points, determined by the Go organization or the match organizer, is given to the second player (White) in an even game (without handicaps) to make up for first-player (Black) advantage.
When ranks are equal, compensation points (komi) are necessary to offset the advantage of being black (moving first). There are still no absolute standards on the number of compensation points due to the difficulty of determining a fair value. 6.5 points are used in Japan and Korea. 7.5 points are used in China and America (see AGA rules). Half-integers are used to prevent a draw.
[edit] Auction compensation point system
As no one can be absolutely sure what is the fair number of compensation points, some advocate another system which is often used in some amateur matches and tournaments. There is no fixed compensation points. The decision is left to both players. They arrive at a value through negotiation and bidding. This is called auction compensation point system.
Examples of auction komi systems include:
- one player chooses how big komi will be given to white and the other player then chooses to play black or white.
- the game is without komi; one player makes the first move of black (not too weak and not too strong) and the other one then chooses to play black or white. This is an application of the pie rule.
- the players do an "auction" by saying: "I am willing to play black against XXX komi" and the player who wins the auction plays black.
