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I'm having trouble understanding how to apply the ko rule. For instance, in the description in Wikipedia, there is an example where the ko rule can potentially apply. But suppose there were two, or three, or four such scenarios on the board. Does one really have to keep track of all the past states of the board? Would you just keep going round-and-round, and whoever created the last original board configuration wins those points?

  • If such a situation arises in your game it would be great if you could put in a photo of it. We could try and analyze it, and I think it might be easier than you expected. It feels (not sure) like you have wrongly interpreted how to treat that situation. Maybe not though, ko tends to be good for surprises :) – mafu Oct 6 '14 at 17:31
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Ko only prevents a player from making a move that would have the effect of returning the board to the position that it was in just before his opponent's last move only. So the only thing you ever need to keep track of is what the board was like just before your opponent made his last move; you cannot move such that it would recreate that position.

All the further description in the wiki is explaining what a player will do if the move they want to make it prevented by ko. They make a move somewhere else on the board that forces black to respond to it; thus freeing them to make the play that they couldn't have played the previous turn due to ko.

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    This is the simple ko rule, which is not the most common. The super ko rule variants prohibit any previous board position. Link: en.wikipedia.org/wiki/Rules_of_Go#Repetition – Forget I was ever here Oct 6 '14 at 9:37
  • Thanks... so, for the more common and complex rule, one would really have to keep track of all previous configurations? I don't know whether it's because I'm a beginner, but my son and I end a game with four or five such "reversible" configurations. – adam.baker Oct 6 '14 at 13:48
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    @adam.baker Yes, you are right. However, such a situation is really rare. If you have a situation with multiple ko at the same time, usually one player will simply close one of them and ignore the other (whatever gives him the best result globally). It is extremely unusual that all ko are connected and one player absolutely cannot give in. In such a situation, superko would apply, and you would have to keep track of the previous situations, or whatever your used rule book states (it's not something everyone agrees on...). Hope that clears it up a bit. – mafu Oct 6 '14 at 17:26
  • @adam.baker: you will seldom need to keep track of many previous positions, as most of the time there are more stones (of more stones of some colour) on the board than at any previous point in the game. Only when you start playing out multiple kos does it become tricky. – PJTraill Dec 13 '15 at 23:52
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You need something like three kos to do this.

But let's say that there are two players, X and Y. Player X takes the first ko. Player Y takes a second ko as a "ko threat." Player X takes a third ko in response. Player Y re-takes the first ko. Etc.

The ko rule serves to prevent repetition between one or two kos. But if there are enough kos so that you can take them in a "round robin," then the game could go on endlessly.

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