In my opinion the goal of a ko rule is to prevent games from not ending. 1: If one player can force a game to an end even when the other player aims at not ending the game, then the rule is good enough. In my previous example I would consider it an undesired side effect of a ko rule that white would win he game. There would be no danger of the game not ending if the ko rule were less restrictive than positional superko. Black should be allowed to capture white. 2: In rare cases the only non-losing way for either player could be to aim for an everlasting game, like a triple ko. In that case an everlasting game it near optimal play for both players. 3: I guess a ko rule does not have to be so restrictive to prevent everlasting games in in general. If it can solve situation 2 while still allowing 1, than that is good enough. Is it mathematically impossible to construct a ko rule that allows 1 and avoid 2? If not, I would prefer keep 1 and leave 2 undefined. I am no rules expert, but I cannot explain more clearly why I would be disgusted by positional superko. It is overly restrictive. Dave
________________________________ Van: [EMAIL PROTECTED] namens Robert Jasiek Verzonden: vr 24-10-2008 14:10 Aan: computer-go Onderwerp: Re: [computer-go] Ending games by two passes [EMAIL PROTECTED] wrote: > Is it correct to end games by 2 consecutive passes? It is correct to end games according to the used rules. Different rules use different numbers of passes, meanings of passes, or procedures assiated with passes. Some examples of numers of passes in actually used rulesets are: 2 passes 3 passes 2 passes + optionally once 2 passes 2 passes + optionally an arbitrary occurrence of yet 2 more passes 2 passes + 2 mandatory further passes after the first, 2 passes etc. One cannot say in general which better because this depends on one's aims. E.g., if the aim is shortest procedure on the rules level, then one would choose 2 passes. E.g., if the aim is to always allow each player a pass as a ko threat while a pass does relieve ko bans sufficiently, then one might choose 3 passes. E.g., if the first pass generates a conditional compensation and one wants to allow each player the filling of 1-sided dame regardless, then one might choose after the first, 2 passes. Etc. > white is alive [under] rulesets with positional superko if black has not > enough eyes left to fill as ko threats? > If that's true, I would be disgusted if positional superko would ever be > accepted as a rule in human vs. human games. Why would you be disgusted? The so called 1-eye-flaw occurs in much less than 1 of 10,000,000 games on the 19x19 board. In the entire history of go, it is reported to have occurred exactly once on the 9x9 board. Why do you dislike rules that enable something possible in theory but never occurring in practice? What do you have against 1-eye-flaw staying on the board at the game end? a) That it is a group with only 1 eye, b) that it is a group with only 1 ko, or c) that there is a string with only 1 liberty? Discussion of (a), (b), and (c): All rulesets used by humans allow games to end with groups with only 1 liberty. Example: # O # . # O . O # O # O # . # O . O # O # O # . # O . O # O # O # . # O . O # O . O # . # O . O # . This example shows two stable anti-sekis. By symmetry, it would be superfluous to prolong the game to dissolve either. If you are disgusted by 1-eye-flaw, then you should be even more disgusted by anti-sekis. I.e., you are disgusted by all rulesets currently used by humans. Strings with 1 liberty at the game end can also occur in hane-sekis, double ko sekis, quadruple kos, etc. Maybe you would human rules to be changed by ca so called greedy rule like "A player may not pass if there is at least one string with exactly 1 liberty on the board." Such would dissolve all those disgusting things. One can even be more brutal in rules design like dissolving all those disgusting ordinary sekis, too. :) If you want to criticise positional superko, then state your first order aims! Which are they? "I hate 1-eye-flaw!"? Why should one particular shape be that all-important while we do not know some 100^500 other shapes yet? List them all, and then tell us what makes 1-eye-flaw so special :) More importantly, why are you worried about a shape at all? Shapes are the consequences of move-sequences and strategic decisions, see http://home.snafu.de/jasiek/j2003.html for a basis with that I defined "eye" formally. Write down your disgusting rules with such a design to enable yourself to define particular shapes in the first place so that you won't overlook any of your potentially hated disgusting shapes... BTW, positional superko IS accepted in some human rulesets like Chinese, Simplified Ing, or World Mind Sports Games 2008. -- robert jasiek _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
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