Hi, I’m trying to comprehend why are not prisoners counted towards final score in Chineese counting.
Let’s look at example with Chineese rules. If Black is playing into White’s territory and White just pass until last stone-imagine that Black doesnt make eye shape-and White takes that group, his score would still be same.
In Japaneese counting, If white passes until last stone which kills the Black group, he could effectively has more points than there are intersection on the board, am I right?
Example 2., on 9x9 board, Black is just filling board, white is passing, and after there are 80 black stones, white kills whole group, after which both players agree to end. Under Chinese counting (Area):
White’s score would be: number of stones (1)+number of territory(80)+komi. Under Japaneese scoring:
White’s score would be: number of territory(80)+prisoners(80)+komi=160+komi.
Is this correct?
I am trying to understand the difference, and this isn’t so clear to me from the rules.
Yes, you are correct, although White’s score would be only 160+komi. Under Japanese rules, each time Black plays a (soon-to-be) dead stone and White passes, White gains one point from the prisoner. If White plays inside her territory to defend instead, she gains no points.
If this bizarre scenario is played out, White can keep stockpiling prisoners to an infinite score, or at least until the opponent runs out of stones.
Note: A common situation where the rulesets diverge in score is the endgame occupation of neutral points (dame): Chinese rules give one point for filling a dame (+1 stone, +1 point) where in Japanese rules it does not matter who fills in the dame.
Because stones are a net gain of +1 and (giving) prisoners are a net gain of +0. This is the same as Japanese rules where stones are a net gain of +0 and (giving) prisoners are a net gain of -1. For both the difference is 1 so it results in the same outcome assuming both people understand the rules and play accordingly (minus only a few rare situations).
The prisoner count is implicit in the way the score is calculated.
Assume all dame filled.
White’s score = W’s Territory + Dead B Stones in W’s Territory + W’s Living Stones + W’s komi. Sw = Tw + Db + Lw + Kw
Black’s score = B’s Territory + Dead W Stones in B’s Territory + B’s Living Stones. Sb = Tb + Dw + Lb
Say M moves were played and there were no passes until end of game. M is even.
The number of stones in W’s prisoner pile, Pb = M/2 - ( Lb + Db )
The number of stones in B’s prisoner pile Pw = M/2 - ( Lw + Dw )
So substitute Db = M/2 - (Pb + Lb) and Dw = M/2 - (Pw + Lw) in equations Sw and Sb.
It looks like if all the accounting records are kept; the prisoner counts can go into the Chinese score count. What else needs to go into the pot?
You normally don’t pass during the game. So yeah, the outcome diverges but only under special circumstances. Usually the results are same or close under different rulesets.
Chinese rules don’t care about valid purposeless moves (like in your examples). I think they are the easiest rules for teaching total beginners, because the teacher doesn’t need to argue with " why can’t I play here".
Once you’ve passed the total beginner stage - hopefully after just one day - then it should not matter much to you what set of rules is used, until you reach pro level.
As others have noted, passing is not common in normal go games, so the example you give is quite extreme. Still, I think what you’re getting as is what happens when one player makes a group that can’t live, but does not understand/agree that it is dead. There seems to be 3 common ways to deal with this problem.
Japanese rules try to define which groups are to be considered alive at the end of the game. I don’t understand the details of how they define that; my understanding is that this only works well if there are enough good go players around that beginners can always ask one to arbitrate if they can’t agree on the status of their groups once the game is finished.
Another approach is to resolve disagreements by continuing the game until the weak group is clearly dead (or until it gets captured). We want to be able to do that without changing the final score. There are two ways to do this. The Chinese rules use Area counting; playing to capture a dead group does not normally change the external borders of the player’s live groups so the final score is not affected. The other way is to have the passing player give out a stone to the other player, which turns out to be equivalent to using area scoring (in your example, white would give 79 stones to black).
For reference, the AGA rule set (http://www.usgo.org/aga-concise-rules-go) is pretty small and allows one to use either area or territory counting with the exact same result. In either case one is supposed to give out a stone to the opponent when passing (this can be considered a practical way to signal the pass); at the end the passing stone is counted together with the prisoners if using area scoring.
For good understanding you may start by the Chinese rule: you count all, stones and empty space inside. You simply count occupation of the space by who
Now we come to Japanese rules where you can count only emptyness if you consider that both sides have played same number of stones (so we can forget about these). It’s convenient but need some adjustment like putting back the prisoners.