# The mysterious game where Black won by 0.5 point even though Black is only leading by 6 points on the board

Black: Dang Yi Fei 9P
White: Byeon Sangil 9P
B+0.5 point

Full kifu here:

3 Likes

Hint 1: It’s using Chinese rules

Hint 2: The special seki on the bottom right

1 Like

I’m counting 184 for Black, 176 for White and 1 neutral point (S2). If komi is 7.5 then Black is winning by 184-176-7.5=0.5.

1 Like

How come you are mixing up stones and points and yet still arrive at the same result lol

To make counting easier.

1 Like

If that’s Japanese rules then bottom right should be 0 points for both sides.

That’s what Chinese rules does doesn’t it?

No Chinese rules count everything as stones. By “stones” here I’m talking about the actual stones on the board and the territories occupied by the stones. They don’t mix the stones and points and say how many stones + how many points etc. Typically a stone = 2 points. So a komi of 7.5 would be 3.75 stones in Chinese rules.

How are you arriving at the observation that “Black is leading by 6 points” on the board? Are you applying territory scoring, when the result actually should be determined by area scoring (since this is Japanese rules)?

I believe that if one applies Chinese (area) scoring rules, one gets the non-mysterious result of B+0.5, as indicated by @jlt above.

Are you simply making a point about how sekis are scored differently under Japanese vs Chinese rules?

That’s an interesting seki. Black can kill white and live with 4 points, but would have to sacrifice 6 points. I don’t think I’ve seen a seki before where it was just about points and not life and death.

1 Like

I don’t use points for chinese rules, so yes I’m talking about counting the points using Japanese rules. Have you counted using Japanese rules?

No, I haven’t bothered manually counting up the score with Japanese rules, but I’m guessing that it might add up to B+6 (before komi)? So, it would be a final result of W+0.5 (with komi)?

Is that it for the point of your post? So, you’ve picked a game where the result under Chinese rules is B+0.5 and the result with Japanese rules is W+0.5.

Yes but can you explain why?

Also you make it sound like it’s very common but I’ve never seen such games before lol

Because seki is treated differently under Chinese rules vs Japanese rules.

Territory surrounded by stones in seki are not counted as points under Japanese rules, but they are counted under Chinese rules.

You can construct games like this (where the scoring differs by an even larger amount, while the life and death status of everything is the same), by including seki positions with unbalanced eyes. For example,

Under Chinese rules, White would have two points of territory (at A and B), while under Japanese rules, there is zero territory in the above position. Flip the colors, if you want to give two extra points to Black.

2 Likes

It commonly comes up in theoretical discussions about Chinese and Japanese rules, which are also rather common on the forums! But these are typically always using

So the rarity here is that it’s an actual game, and one that has a 0.5 difference. I guess actual games with these kind of positions are somewhat more common but in most cases there’s no difference in winner so they are not so notable.

3 Likes

I mean explain using this game, not explain using another example

Yes, but I wonder if there’s a constructed game where black wins by 0.5 even though he only leads by 6 points on the board when the komi is 7.5 points.

There are two simultaneous effects going on here:

1. Black played the last move (by filling the last dame). This gives Black an extra point under Chinese rules (relative to Japanese rules), and counteracts the higher Chinese komi of 7.5.
2. There is a seki with unbalanced eyes, giving Black an extra point of territory.
6 Likes