ChineseCounting (version 21)
The central idea in Chinese counting of territory is that your territory is the number of empty spaces you control, plus the number of stones you have on the board.
Some things this changes from Japanese counting:
- Playing in your own territory doesn't reduce your score.
- Playing a stone in a dame increases your score
- You can get points in seki
- You don't have to keep track of prisoners
- You don't have as many special rulings? as in Japanese Counting
- You have to do a lot more counting
There are almost certainly details to the counting which I have not listed here, but this gives you an idea of how it works.
Note that "playing in your own territory" will cost you points, unless you do it after all dame points are filled in. Why? Because a play in your own territory is just like a pass play, and if there are dame or real points left on the board then your opponent can take one point more. I.e. if there are 10 dame points left on the board and you play 10 times in your own territory instead of taking half of the dames you lose 5 points. --ArnoHollosi, 1d
I just remembered that I once heard a description of the rules of WeiQi which stated that the two spaces that a group used for its eyes did not count as territory (i.e., that a player's score was all the spaces that they could place stones on). This scoring system has the nice feature that splitting your opponents stones into two groups makes them lose at least two points. Can anyone verify whether this is a feature in current Chinese scoring? --FCS
I believe this went out of general use in China in the early part of the 20th century, presumably because the strong players were learning from Japanese sources.
The rule about "not counting 2 eye spaces" is from the ancient Chinese rules. In the ancient rules, passing is not allowed -- this translates to the "don't count the 2 spaces for eyes" rule (AKA the "2 point group tax"). John Fairbairn could probably give you more details about this history.
See Ancient Chinese Rules And Philosophy for more on this.
I don't think the two point 'tax' is equivalent to disallowing passing (if you mean that you lose if you have no move other than passing). In the diagram shown, White has three points after tax, while Black has four. But I think White can win the no-pass game, whoever starts.
In the position above, white has played 20 stones (that we can see, perhaps more if there have been captures) and black has played only eleven (again, 11 that we can see). Also notice that W occupies much more area than black. While black has more "Japanese" territory in the diagram above he white must have at least 9 prisoners (since black is not allowed to pass). By either Chinese area counting or Japanese territory counting white is way ahead and should win so saying that the diagram above proves that "2 point group tax" does not equal "no passing allowed" is false.
Of course black and white both have the same number of groups above (1 each) so any possible tax cancels out. A proper counter example to my claim would probably have an uneven number of black and white groups.
No. Consider this version on a 13x13 board. Each player has two groups and 77 stones. White has three points after tax. Black has four. Black to play, White wins.
Excellent! I had a suspicion I was wrong and your last diagram proves it.
Ah, I think I remember a modification to the ancient rules that do properly implement the 2 point group tax. Here it is:
- both players must move. The first player who can not move loses.
- A move consists of placing a stone on the board or returning a captured stone to your opponent.
I believe these modified ancient rules give the desired 2-point group tax when used for your diagram above.
for example, if black has to move next then he should win by 1 move.
Black 7: return the captured stone white 2.
When black plays 11 at A white has lost.
If we start the problem with white moving first then black wins by 2 points. (this is left as an exercise)
Thanks for helping remember the proper rules for implementing the 2-point group tax.