Scoring question 0.5 stone difference

Yes, but the unfilled ko question only arises with territory scoring (no reason not filling with area), and you cannot use (strict) superko with territory scoring anyway.

I mean it doesn’t really only arise with territory scoring.

Players can resume with area scoring too and recapture the ko in principle.

You don’t have to have an area scoring ruleset with superko, even though it seems that most do in some form to offset things like send two return one and other situations.

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Sure, like Chinese (ko) rules you can have area without (strict) superko, and then you can recapture after passing - but why would the opponent not fill (and give you the option to recapture) with area? They get the same area-point for a filled ko than for an open ko.

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I guess the term is no so formally defined, but rather just something coined to try to describe this particular weird situation. However, another example is the double-ko seki, which has also been called as an anti-seki. See: Anti Seki at Sensei's Library

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IIRC, the Dutch variant of Japanese rules has a notion of requiring 3 passes to end the game in a situation like that. So after the passes of move 291 and move 292, black would just recapture the ko (no resumption required). The existence of this rule urges white to connect the ko on move 292 (instead of passing), otherwise white would risk losing a point.

Clarification please. I have always understood that one could not use a pass as a ko threat. In other words, if I pass and my opponent passes, and I resume the game, then I should not be able to retake immediately, because doing so would repeat the board position. The whole point of the ko rule is to not repeat the board position, so allowing a pass to function as a ko threat seems quite contradictory. I don’t feel like looking it up, but I seem to remember an explicit rule against repeating the board position.

This understanding (in the context of the Japanese rules) is incorrect.

In the Japanese rules of go, there is no broad prohibition on repeating previous board positions (i.e., there is no superko rule in the Japanese rules). During the alternating play phase, only a simple ko rule is applied:

A shape in which the players can alternately capture and recapture one opposing stone is called a “ko.” A player whose stone has been captured in a ko cannot recapture in that ko on the next move.

Thus, playing elsewhere, or even just passing, lifts the ko ban, since the ko ban is only in force for one move.

During the life and death confirmation phase, only passes can be used to lift ko bans:

In the confirmation of life and death after the game stops in Article 9, recapturing in the same ko is prohibited. A player whose stone has been captured in a ko may, however, capture in that ko again after passing once for that particular ko capture.

The only part where the Japanese rules address repeated board positions is in the case of no results (due to longer cycles like triple ko):

When the same whole-board position is repeated during a game, if the players agree, the game ends without result.

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Thank you. That is very clear.

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What is the Dutch variant of the Japanese rules? Is there a version of these translated into English?

Do I get it right that you ask for the English-Dutch-Japanese rules? Gosh, I’m glad go rules are so much more simple than those of - say - chess!

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We should just adopt the simplest rules set, Stone Scoring, after machine translating it through a dozen different languages in turn.

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The problematic way of Western rule introductions seem to be at fault here (which imo also drives away a significant % of interested beginners).

As yebellz mentioned the ko rule (as opposed to the superko rule) does not forbid repeat of earlier board positions. Instead, “ko” is a shape, and the rule only forbids (time-wise) immediate recapture in that shape (no need to remember earlier positions).

Recapturing after a pass is essential for territory scoring. But I think Western rules significantly misunderstood even Chinese rules here (and not just their practical treatment of triple kos).

I think the extended Dutch version of go rules (as used in the Dutch national championships) existed on paper in the 90s and earlier, but I can’t find them online. The website of the Dutch go association only mentions Japanese rules without stating their contents. It only has some documents about match rules and tournament rules, which don’t go into much details about game rules.
I can only find a comment about it by Dutch 3d and mathematician André Engels on this page: Passing at Sensei's Library.

I could ask former (current?) Dutch go referee Niek van Diepen if he has some knowledge about it and perhaps an official document referring to this rule.

Edit: Oh, the NGoB (Dutch Go Association) website does state the Japenese rules, but it seems to be just a translation of the 1989 Japanes rules. Spelregels - Japan | NGoB (www.gobond.nl)

Edit 2: Above diagram J of those rules it says “In diagram J een voorbeeld van opnieuw slaan na passen.”, “In diagram J, an example of recapturing after passing.”, which seems to imply that recapturing a ko after 2 passes is allowed.

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