# How big a difference can Chinese and Japanese give in local scores (e.g. tsumego)?

I thought that there should rarely be a difference of more than one point between Japanese and Chinese scoring, as explained here Logical proof of the equivalence of territory and area scoring at Sensei's Library.

I know there are some exceptions to this, such as sekis with eyes, playing inside your own territory, or an uneven number of passes. But the rules still seem different for local scoring; I came up with this seki example where the difference is >1 and none of the exceptions apply:

If white plays at the marked point first, they live in seki. If black plays there first, white dies.

So how does who plays first affect the score in Chinese vs Japanese rules?

Chinese: If Seki, white scores 10 and black scores 3, so a net +7 for white. If black kills, white scores 0 and black scores 15, so a net -15 for white. Total swing is 22.

Japanese, If Seki, everyone scores 0, so a net 0 for white. If black kills, white scores 0 and black scores 20, so a net -20 for white. Total swing is 20.

Can someone explain to me why the difference between the scoring methods is greater than 1 in this example? And if the âmax difference of oneâ rule doesnât apply when scoring locally, then how big a difference between the counting methods is possible in local scoring? Thank you!

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Great question!

In general, every move under Chinese rules has +1 extra âpoint valueâ compared to Japanese rules (since the stone itself is worth a point).

For the final game result, this only adds up to at most one extra point for black, if black made the last move and thus one more move than white in total.

But, if you count the swing difference between one black move and one white move, there will be an extra point âin both directionsâ under Chinese rules, adding up to a swing value that is 2 higher than it would have been under Japanese rules.

So actually this has nothing do with the Japanese seki rule - you can do the same calculation for the triangle move here and get the same 2 point discrepancy:

To be able to fairly compare move values to each other, it makes sense to divide the swing by the difference in the number of black/white moves in the two variations (the âlocal tallyâ). We then get something called the âmiai valueâ of the move.

In your example the local tally is 2, so the miai values areâŚ

Japanese rules: swing/tally = 20/2 = 10
Chinese rules: swing/tally = 22/2 = 11

âŚand the Chinese value is indeed exactly 1 larger than the Japanese value, as it should be!

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Thanks! So re: this question:

if the âmax difference of oneâ rule doesnât apply when scoring locally, then how big a difference between the counting methods is possible in local scoring?

It sounds like the answer is 2? Although Iâm still not totally clear on why .

if you count the swing difference between one black move and one white move, there will be an extra point âin both directionsâ under Chinese rules

This is the part I find confusing. If thereâs an extra point in both directions when this happens under Chinese rules, why is it impossible for this to translate into an extra point in both directions in the final score? Thanks again for your reply!

(Also it makes sense as you say that seki isnât what causes this; you can get a Japanese 14 pt vs Chinese 16 pt swing here with no seki):

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Now somebody compare the scores of playing the last dame in both rulesets

^^ I suppose that was this actually

Imagine a game of go as the two players taking turns making moves of different simple values, and these will add up to give the final result. For instance, letâs say we have moves of values 5, 3, 2 and 1 points under Japanese rules. Black goes first and takes the 5-point move, then white takes the 3-point move, black the 2-point and finally white gets the 1-point move. The score from blackâs perspective is:

+5 -3 +2 -1 = 3

Now letâs say we look at the same game under Chinese rules. Here each of the values will be 1 bigger, so we get:

+6 -4 +3 -2 = 3

Each of the individual moves were 1 point bigger, but the final score is the same, because black and white made the same number of moves! If you retry it with an odd number of moves, youâll find a 1-point difference between Japanese and Chinese rules.

The swing value for Chinese rules you calculated in your first seki example was +7 - (-15) = 22. But both the 7 and the 15 has one of those hidden +1âs inside of them, which adds up to 2 extra points. This is what I meant by âan extra point in both directionsâ. Hopefully by the numeric example above itâs clear that throughout a whole game, all these +1âs in both directions basically cancel out.

As for the âhow big a difference between the counting methods is possible in local scoring?â question - if you have a bigger local tally you can get a larger difference in swing values.

For instance, letâs say we try to calculate the value of this ko:

Either black takes and then fills the ko, or white just fills the ko.
Under Japanese rules, the swing between the two outcomes is 1 point.
Under Chinese rules, the swing is 4 points.

Where did the 3-point discrepancy come from? In the first variation, black makes two additional moves. In the second variation, white makes one additional move. This adds up to a local tally of 3.

So if you want to keep making that number bigger, you can look at multi-stage koâs like this one:

(here the difference between the two extreme results is a local tally of 5: black could take twice then fill, or white could take once then fill)

However, the larger swing value doesnât correspond to anything meaningful in terms of gameplay! You donât usually need to prioritize endgame moves differently depending on the rulesets, not until you reach the very late endgame and the parity of dame starts mattering.

What is meaningful in terms of gameplay is the miai value. Those are consistently 1 point bigger under Chinese rules, no more and no less (ignoring seki and other weirdness for the time being). But this means the relative importance of different moves will stay consistent across the rulesets.

In summary: divide by the local tally and everything works out more nicely

If dividing by 2 still feels a bit arbitrary for your examples, hereâs another way of looking at it, starting with a simpler situation:

Black can play A2 to make 2 points (letâs use Japanese rules for now). But itâs equally likely that white will get to play A2 and black will make 0 points. If we wanted to count how many points black has on the full board, giving black either 0 or 2 points is inaccurate, because we donât know which one it will be. Itâs better to say that black will get 1 point on average.

(If there happens to be two of these situations on the board, black will get one, white will get the other, so black will get 2+0 points, which is the same as the 1+1 we would have counted on average without knowing who gets what.)

So in the current position black already âhasâ 1 point, even without having played A2. Then by playing A2, blackâs score will go up to 2 points - a gain of 1 point. Similarly, if white plays A2, she will take away 1 point from black.

The current score is +1. Black can move it up to +2, or white could move it down to 0. The swing between the two outcomes is 2 points, but it turns out to be more generally useful to think of how far each individual move changes the score from the previous average - in this case, 1 point per move.

Thus under miai counting, A2 is a 1-point move (not a 2-point move as we might otherwise think!). The advantage of this way of counting is that it letâs us compare values between more different situations - for instance the multi-stage ko above. The total swing between the two extremes of black/white winning the multi-stage ko is quite large, but either player needs to spend several moves to get that full value. Meanwhile, the other player is profiting elsewhere. So in an actual game, what we care about is how much value we can get per move.

To bring it back to your first example, we could say that black already has 10 points on average (Japanese rules) here:

Then one of two things will happen: Black can play the triangle and gain an additional 10 points, or white can play the triangle and steal blackâs 10 points.

For Chinese rules, the average for black is 4 points, and from there black can move it up to 15 points or white can move it down to -7 points (sorry about switching your sign convention ). The individual moves have value 11.

Hope that makes these 20/2=10 and 22/2=11 values seem a bit more natural, rather than something I just pulled out of a hat

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Ok this is tentatively starting to make senseâŚ

Original example

Hopefully by the numeric example above itâs clear that throughout a whole game, all these +1âs in both directions basically cancel out.

I think this idea is the most intuitive for me. The idea is that you can disregard the extra point you get when you make a move under Chinese rules because it applies to every single move! Or at least, doing this will not change the final score by >1 point.

So if I do this in my example, the Chinese swing would be as follows:

White first, white scores 10 - 1, black scores 3, 6 points to white.
Black first, black scores 15 - 1, white scores 0, -14 points to white.

Total swing is 20, same as Japanese rules, hooray! Does this make sense as an idea, or am I just kidding myself?

Kos

This logic doesnât work for the ko examples, but that also makes sense to me:

If black manages to play first here at the end of the game, they will take more than >1 point of additional swing under Chinese rules compared to Japanese rules, but thatâs because theyâve managed to play two additional non-zero moves compared to white.

i.e. the number of passes arenât equal, so the score will differ by >1 point depending on the ruleset.

I also think a single point ko like this is an exceptional area where move value is slightly different depending on rulesets in the endgame. e.g. Playing at the ko instead of the triangle is slightly more valuable for both sides under Chinese rules, but the moves are equivalent under Japanese rules (assuming no ko threats?) e.g. two points for black to capture and fill the ko v.s. playing on the triangle and a neutral point is 4 vs 3 points under Chinese rules, but 1 vs 1 point under Japanese rules? And this seems confusingly related to how the ko impacts who gets to play the final valuable point?

FinallyâŚ

the relative importance of different moves will stay consistent across the rulesets.

Nice, this is the main reason I asked the question; I wanted to make sure area vs territory scoring doesnât change the ânext biggest moveâ in situations that donât affect who gets the final valuable move. So I can count swings using area scoring even in Japanese games .

Thanks for your help with this!