AGA Rules
The AGA rules are the rules of Go adopted by the American Go Association.
The rules are intentionally formulated so that there is no difference whether area scoring or territory scoring is used[1]. This is made possible by requiring white to make the last move and incorporating "pass stones". This means that if white passes first, he or she must pass again after black, handing over a second pass stone. Eyes in seki situations are counted as territory in territory scoring and are part of the area in area scoring.
They prohibit suicide.
(They are therefore quite similar to Chinese rules.)
They use the situational superko rule:
- It is illegal to play in such a way as to repeat a previous board position from the game, with the same player to play.[2]
In addition white must make the last play.
In theory the rules allow free placement of handicap stones, but in practice the traditional Japanese placement is usually used. This is mentioned in the commentary at http://www-2.cs.cmu.edu/~wjh/go/rules/AGA.commentary.html
The complete text of the rules can be found here: http://www.usgo.org/resources/downloads/completerules.pdf
Notice that the 1991 date in the above document is wrong: the rules were changed in August 2004, with komi set to 7.5 rather than 5.5, effective 2005; see point 9 in http://www.usgo.org/resources/downloads/2004-minutes.pdf
The French rules and the British Go Association rules are essentially the same as AGA rules.
[1] Territory counting (with pass stones) is used by default unless the players agree before starting play to another counting method. The Mathematics of Scoring shows the equivalence algebraically at the end of the page.
[2] Robert Jasiek: Many readers of the rules text read it as if it were meant to describe situational superko (but the major author of the rules, Terry Benson?, insists that natural situational superko was meant).
Willemien explanation about natural situational superko with example (I found editing Robert Jasiek's post inappropriate, maybe he disagrees with the explanation given)
Discussion
According to http://www.britgo.org/rules/aga.html the BGA has decided to adopt the AGA rules in october 2007. The document mentions that the board is proposing to get this change accepted (or denied) at the 2008 Annual General Meeting. Does anyone know if the 2008 AGM has already happened, and what the result was if it did? --Herman Hiddema
RobertJasiek: The AGM has taken place during the 2008 British Go Congress. The motion to adopt the AGA Rules has been accepted unanimously.
Herman Hiddema: Ok, thanks! I couldn't find anything about the AGM on the BGA website :-)
Strongeye: The AGA rules specify territory as: "Those empty points on the board which are entirely surrounded by live stones of a single color are considered the territory of the player of that color." But neither the rules, nor the commentary text, specify if seki positions are a) alive or dead, or b) eyes in seki strings count as territory. A direct and literal interpretation as far as I can tell would mean that they do, but it isn't explicit in this. Can anyone clarify? Thanks.
- Strongeye: ok, so I have found clarification for this [fake URL removed] where it says "The rules count surrounded points in seki, but not the 'neutral' points."