Rules Beast 1 (version 42)
Here, White to move had better connect in the lower left, else
Black can exploit the superko rule to capture a white group. Hint: Black aims to make it illegal for White to capture in the top-right a second time. (Play below.)
I don't see these strange consequences as an indication that there's something wrong with the superko rule. In fact it seems to fit right in with the other simply-stated Go rules that yield a game so rich in strategy and subtleties.
I think the final paragraph is a partisan statement, by the way. If various organisations of standing in the go world have been persuaded to adopt superko, was it really to introduce more 'subtleties', or because it was represented as suppressing others?
I am pretty much in agreement with you, Charles. The behavior of this board under most rules sets with a superko rule seems to me to be an unintended consequence.
Christos Dimitrakakis This problem does not occur under a situational superko, since in one occasion it is black who is to play, while on the other it is the white player whose turn it is to play. Thus, while there is a repeated position, there can be no cycle.
Bill: The banned position is the one after , which White would repeat on move 11, recreating the same situation, with Black to play. So it does occur under a situational superko rule.
Under Spight rules White can take the stones, since White's pass () lifted any ko or superko ban.
Under Kee Rules:
triggers a cycle, but Black is prohibited from playing in the remainder of the game because White has a normal pass play within the cycle but Black has not. White wins by playing the remainder of the game by himself alone.
Cycles, besides ko, are not prohibited by LJRG. Instead, one may (if passing wouldn't end) remove the cycle.
If White passes and Black disturbs, the situation after is similar to the one after (with no history, trees growing out of them are identical). LJRG now allows Black to
- clear the cycle arena (top three intersections of the right-most column) -- thereby earning one white captive and prohibiting any further play in it -- and
- do a move.
Since there is nothing worth continuing, Black will skip the second part, White will pass, and Black will pass too, ending the game (ultimately): W+5 (no part of the board is controled, and there are two white and seven black captives).
Since the whole mess doesn't pay, Black will rather pass after White did initially: tie (neither any control nor any captives).
Thus, White should have captured the black loner in the seki instead to pass initially: W+1.
Osh?: maybe white is better to bring everything to Seki? If there was a komi...
By it is seki in left below side. If eats...
White cuts then black captures this white stone, but after that white takes three black stones and...
Black cannot go here, else the white group is alive. So it is unreasonable for black to reply in left below side