Cheating in Chinese Rules: 7.5 komi

From the European point of view, we are used to Japanese rules. (Though not the strict ones, but the EGF adaptions. More on this later.)

Chinese rules entered the European Go scene with the arrival of CEGO. The Pro Qualifications, Grand Slams, and Grand Slam Qualifications are played under Chinese rules.

(It seems to be common practice for sponsors to enforce their preferred rule sets; e.g. EYGCs and former EGCs used ING rules.)

This post is directed at those who have zero knowledge about Chinese rules. If you already know more than me, please move on.

If you want to learn about obscur details, go to Robert Jasiek’s homepage.

Chinese rules for dummies

In Chinese rules, both the territory you surround and the number of your living stones on the board count. This so-called area scoring has the effect that playing in your own territory (after dame) doesn’t lose points. [I’m guessing that this is the reason why in territory scoring rules like the Japanese ones certain rulings are in effect for specific positions (like the bent-four corner); playing in your territory to prove that some group is dead loses points.]

So don’t forget to play dame:p

Typically, at the end of the game, there is no dame left. This means, the territories and living stones of both players add up to 361. Therefore, it is necessary to count only one colour. If you have never seen it done before, you can think about the smartest way of counting territory+stones for one colour.

For some reason, komi is 7,5 points. (They call it 3 3/4 stones, but I’m going to go by 7,5 points here, it’s the same.) This gives us the following typical results:

Black White Difference
on the board
Result
181 180 1 White + 6,5
182 179 3 White + 4,5
183 178 5 White + 2,5
184 177 7 White + 0,5
185 176 9 Black + 1,5
186 175 11 Black + 3,5
etc. etc. etc. Black + etc

As you can see, there is always a gap of 2 points. Just keep in mind W 177 and B 185 as the respective minimum to win.

I hope this made sense because if it didn’t, the next sections are going to be weird.

Exception

What to do when not all the dame can be filled?

seki1

Seki does happen sometimes. In this case, the unplayed dame points are shared. Each side gets appointed half a point (or stone? Idk) per dame, so in this situation both Black and White get one point each and the table above can still be used.

It is quite rare that there is an odd amount of unfillable dame on the board. Basically I’ve never seen this happen and matter enough to change the result:

seki2

In this seki, both groups have an eye and their shared liberties is inevitably an odd number. (I.e. 1.)

By the way, the one point each in the respective eye is counted. The only problem is the shared liberty, from which both sides are claiming half a point. In this rare occurence, the following can theoretically happen:

Black White Difference
on the board
Result
183,5 177,5 6 White + 1,5
184,5 176,5 8 Black + 0,5
185,5 175,5 10 Black + 2,5

The possible results still show a gap of 2 points, but they get shifted, if you know what I mean. So Black can win with 184 if he has a shared dame lying around. (Note that another seki like that cancels out the uncommon situation.)

This also holds when the players forget about a dame, like I almost did in this dramatic game from the 2017 Pro Qualification:

seki3

Luckily, I (White) saw the last dame just in time and the result was B 184=W+0,5. If I had passed instead and Black had got the dame, it would have been B 185=B+1,5. But he wouldn’t even have had to play anymore, because if the dame had been left open, it would have been B 184,5=B+0,5.

Comparison with Japanese counting

Now I’m going to translate the typical results to Japanese rules with 6,5 komi. In territory counting, the possible results shift according to who got the last dame.

Area count Last dame Chinese Japanese
B 183/W 178 Black White + 2,5 White + 2,5
B 183/W 178 White White + 2,5 White + 1,5
B 184/W 177 Black White + 0,5 White + 0,5
B 184/W 177 White White + 0,5 Black + 0,5
B 185/W 176 Black Black + 1,5 Black + 1,5
B 185/W 176 White Black + 1,5 Black + 2,5

Thus, according to this table, I won the aforementioned game solely by the chosen rule set.

2 thoughts on “Cheating in Chinese Rules: 7.5 komi

  1. Pingback: Cheating in Chinese Rules: 粘劫收後 | Viktor Lin

  2. Pingback: Gengar | Viktor Lin

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