Japanese rule; last move by black and stone in one's own territory

[yebellz]

@smurph

The discussion started when andysif (sort of correctly) stated that there could be a game whose result under J rules differs from the result under C rules by 1 point.

That is true, provided there are two seki on the board.

I guess I’m still confused. It seems like we’re agreement about what andysif was originally talking about: a finished game where the result (score margin) under C rules is one point different than the result under J rules. This can be demonstrated with a single diagram showing a finished game involving no ko or seki:

Can you explain why seki is necessary? It seems that you are thinking of a different situation where seki would be necessary.

I believe so since you also stated the following:

@smurph

I asked him to produce TWO diagrams showing final position A and final position B of a game without any seki, one diagram where black took the last dame and one diagram where white took the last dame. I further asked him to show that both only differed by 1 point.

This is talking about a completely different comparison.

andysif’s post and my reply were originally talking about a one-point difference between the scoring margins produced by the J and C rules applied to the same finished board position. However, your follow-up is talking about one-point swings produced by which player takes the last dame. I was not trying to make any claims about this different kind of situation, but since you diverted the discussion toward that topic, I tried to figure out what you were really after by offering another example position.

I never claimed that the swing would not be two points under Chinese rules. I just wanted to mention that points that appear to be dame, could still cost a player a point under Japanese rules if not taken in time.

@smurph

Maybe it helps to also point out that C3 in the first example is not dame, but sente for both. C3 in his “better example” is also not dame, but in fact sente for white.

My mistake for calling those example points dame, if that’s not the correct term. I’ve always thought of such situations as “false dame”. Maybe that’s abuse of terminology, but people do say things like:

@Illion

When is a dame not a dame?

[yebellz]

@3mushroom3

I would think a game that’s been matured from hundreds of, if not thousands of, years, should have reached a satisfying status regarding rules. (I like the game because it’s so precise, so logical and so satisfying in learning. It’s like a well developed physics theory where everything is perfectly consistent with each other)

I find the conciseness and elegance of the Tromp-Taylor rules to be very satisfying:
https://tromp.github.io/go.html

@3mushroom3

I don’t understand which one is better and why there was such discrepancy in the first place.

Which one is “better” is still hotly debated to this day. In terms of reducing disputes and simplifying things, I think area scoring and superko has its advantages. Perhaps the existence of the discrepancy has more to do with tradition and politics than logic, but I’m not a historian.

[yebellz]

@smurph

Only if there are 2 seki on the board.

@smurph, I’m really curious… what situation were you imagining when you said that two sekis were necessary?

[Bitt]

Oh, look, a sleeping dog…