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Terry Benson on AGA rules When we introduced the AGA rules in the US there were a lot of players very concerned at first at the change. What would it mean? What did they have to pay attention to? The transition however went very very smoothly. I think that's because they are really rather intuitive once you accept the area (Chinese) view of the game instead of the territory (Japanese) view, the play of the game is virtually unchanged, and the clarity about the end of the game is welcomed once it's appreciated. The main difference is of course that you have to fill all the dame during play and the dame matter in the score. That is, if you miss a dame and pass a stone instead, your opponent gains a point. It makes the end of the game far more interesting especially for amateurs. It's worth noting that the World Amateur Championships Rules also required filling in all the dame. (Not sure if they actually do it or not.) To a Japanese, filling dame is annoying and unnecessary. To a Chinese it's the most natural thing in the world. The difference is only a point of view and the underlying aesthetics. In our experience players quickly get used to it and don't mind. That's because it makes the end both more interesting (watch out for those single sided dame and te-ire moves) and it makes the end much clearer. There's no more of this hemming and hawing of "Gee I think we're done" or "Do you see anything left to do?" or dozens of other verbal comments which leave open the possibility of gamesmanship and misunderstanding. I can often remember players asking if the game was over when I knew there were some messy items still to do on the board as the dame were filled and I wanted my shot at them without having to signal that they were missing something. Now we just say, pass a stone when you're done. There couldn't be a clearer signal and it's easily understood across languages and go cultures. In an even game, parity means that the last pass by white is very, very rarely going to change the result of the game. I attached below a paper I wrote some time ago (right after the passage of the AGA rules) called "Only a passing matter." The exception (and my guess is in the 1/10000 range) is when 1) there is a seki on the board with an odd number of eyes+dame, 2) when black plays the last dame on the board, and 3) black is ahead counting territory and prisoners but no pass stones by exactly 7 points. In that case the last pass stone by white would change the result (with 7.5 komi) from what is "expected" by Japanese rules trained players. (It is exactly the result which a Chinese trained player would expect because Black got the last dame.) I hope everyone will agree that a very rare occurrence is not a substantial point.
Only a Passing Matter In an even game with 5 and ½ komi if white must make the third pass at the end of the game, that stone does change the score (from the traditional Japanese count) but does not change the result unless there is a seki situation with an odd number of shared liberties. The reason is a matter of parity. Assume that the players alternately fill in any dame. (This doesn't affect the traditional score in any case.) Only if Black plays the last stone on the board does White - under the new rules - have to hand over a third pass stone. If Black plays last, then the number of stones played by both players must be odd. Since the board has an odd number of points (361), the total territory (empty space after filling in the prisoners but WITHOUT pass stones) will usually be even. (The exception is a game with an odd number of shared liberties in seki.) When the territory is even, the difference in the traditional (Japanese) scores of the two players must also be even: 2, 4, 6, etc. (e.g. 33 - 27 or 32 - 26). (An odd difference would make the total territory odd, e.g. 33 - 28 or 32 - 27.) Looking at a difference of 4 and 6, if White is behind by 4 points (traditional count) and gets 5 ½ komi, White wins by 1½ . The additional pass stone reduces the victory to ½ point, but White still wins. If White is behind by 6 points (traditional count) and gets 5 ½ komi, White loses by ½ point. The additional pass stone makes the score 1 ½. White's loss is just one point bigger. The third pass stone also does not affect the result of handicap games of 3, 5, 7, and 9 stones. But, because of the parity of the stones played and the points of komi, it can affect the result in handicap games of 0 stones (½ point komi to white), reverse komi of 5 ½ to black (reverse komi should perhaps be 4 ½ for this reason), handicaps of any even number of stones (2, 4, 6, etc.), and even games with a non-standard 4 ½ or 6 ½ komi. |