This time "In the Dark?" describes the various rule sets that are in use around the world. The series "Get Strong at Scoring" that ran in the Journal looked at some of the counting methods in use. More details of each rule set can be found in the book "Go Player's Almanac 2001" available from the BGA, price £22.
Chinese rules, because of the game's origin, are the oldest; they are area-counting rules. That is stones and territory are counted and you simply need over half the board. Prisoners are not needed and are thrown back in to the supply of unplayed stones. Seki is scored, with neutral points shared. Counting is usually done by rearranging stones and territories. Originally under Chinese rules it was the person who could legally put the most stones on the board who won, but not filling each group's two eyes was effectively a group tax.
Japanese rules are the most commonly used in the west and are normally used in all BGA events (subject to their interpretation by the referee). They were formalised in 1949 and have periodic revisions (such as that in 1989). They are territory rules where only empty spaces and prisoners count towards the score. They are defined in three parts: rules, commentary and examples. The examples contain judgements on many strange and unusual positions such as triple kos and round-robin kos.
Korean rules are territory rules like Japan, but are formulated differently and are not usually described in listings of rule sets.
The New Zealand players, being on the edge of the Go universe, devised their own set of rules which are very short with some explicitly recursive definitions. They are area-counting rules, but instead of rearranging stones and territories to count the score as in Chinese, players count the score point by point without any rearranging.
The Ing SST Rules of Goe were derived in 1975 by Mr Ing Chang-Ki, president of a large computer company. They have been officially used in Taiwan since 1977 and are used in various Ing-sponsored events around the world. A fund was set up to promote the rules worldwide which continues to support Goe in Europe and America. The principle is area counting (SST is Stones and Spaces are Territory) but play uses exactly 180 stones of each colour held in special Ing measuring bowls. If you can fill in your own territory at the end with unplayed stones and have some space left over, then you have won. Unfortunately the rules have very complicated (or badly described) ko rules to avoid special positions.
The American Go Association (AGA) adopted its own rules in 1991. They are designed so that area counting and territory counting give exactly the same result (except in a few special positions); players can choose which way to count. To this end white must play last, pass stones are given and territory is counted in seki.
From 2005 an International Rules Commission has been working to try to find a ruleset suitable for all international events.
The material on this page was written by Tony Atkins, and has appeared in the British Go Journal. Tony, and the Editor of the Journal, have kindly allowed it to appear here.