What are the difference between ancient-territory and stone-scoring rules?

[dany52]

What are the difference between ancient-territory and stone-scoring rules?

[lightvector]

Very similar to the difference between Japanese and Chinese rules.

Stone scoring is like Chinese rules minus 2 points per independently living group, as well as no points for territory in sekis. This is the mathematically more elegant ruleset due to being equivalent to just saying both players should fill up their territories except for 2 eyes with as many stones as they can, and then the person who has more stones is the winner (and in modern times we would also adjust it with a komi, requiring black to have more stones by some minimum margin). But my understanding is that there is no direct evidence, only indirect evidence, that this form of scoring was ever used historically. In particular, there is some linguistic mentions of such a scoring being used, but no actual surviving game records to support and confirm it, so whether it was actually used is, to my non-expert knowledge, not entirely clear because translating ancient Chinese is not trivial and without game records it's at least arguable if the interpretation of ancient writings is correct.

Ancient-territory is Japanese rules minus 2 points per independently living group. So unlike stone scoring, filling dame with stones is not worth points, for example, because it doesn't increase the surrounded territory. In this case, my understanding is we have relatively clear evidence that this form of scoring, or something very close to it was in fact used historically, because there are a few surviving game records with recorded results that are consistent with this and not consistent with stone scoring. Unlike stone-scoring, however, there isn't such a mathematically clean way to express the scoring like "fill up all the territory and count the number of stones on the board".

[simonguoxm]

Yes, I agree.
Ancient rule is mathematically equivalent to stone-scoring, but no evidence says it was based on stone score. We created a rule
called "Natural rule", which clearly say that the score is the number of stone. This is also called "Population score".

Stone scoring is like Chinese rules minus 2 points per independently living group, as well as no points for territory in sekis. This is the mathematically more elegant ruleset due to being equivalent to just saying both players should fill up their territories except for 2 eyes with as many stones as they can, and then the person who has more stones is the winner (and in modern times we would also adjust it with a komi, requiring black to have more stones by some minimum margin). But my understanding is that there is no direct evidence, only indirect evidence, that this form of scoring was ever used historically. In particular, there is some linguistic mentions of such a scoring being used, but no actual surviving game records to support and confirm it, so whether it was actually used is, to my non-expert knowledge, not entirely clear because translating ancient Chinese is not trivial and without game records it's at least arguable if the interpretation of ancient writings is correct.

Ancient-territory is Japanese rules minus 2 points per independently living group. So unlike stone scoring, filling dame with stones is not worth points, for example, because it doesn't increase the surrounded territory. In this case, my understanding is we have relatively clear evidence that this form of scoring, or something very close to it was in fact used historically, because there are a few surviving game records with recorded results that are consistent with this and not consistent with stone scoring. Unlike stone-scoring, however, there isn't such a mathematically clean way to express the scoring like "fill up all the territory and count the number of stones on the board".

[dany52]

I tried to analyze the "Game for a Pair of Gold-Petaled Bowls" using katogo and faced with scoring issue.

According to the "Getting the Last Play, Bill Spight, [BS]", the game's rules was:

The game was played under territory scoring with a group tax of two points per group.

But according to the "Game for a Gold-Petal Bowl, circa 850, r/baduk, [RB]", the game's rules was:

The game ends with Black winning by 1 point with Chinese Scoring. However, at this point in Go history, Stone Scoring was used.

"territory scoring with a group tax" = katago ancient-territory

"Stone Scoring" = katago stone-scoring

But which of these KataGo rules correspond to this game?

I analyzed Bill Spight's White move improvement

Black won by one point, but White could have evened the score by getting the last play

When I used the ancient-territory rules I got the right result - Jigo
But when I used the stone-scoring rules I got the wrong result - W+1

Then I tried to understand why the results were different. And in this I was greatly helped by "The History of Go Rules, Chen Zuyuan, [CZ]".
According to this work for this game

Essentially they were territory counting, but actually a method of stone scoring

and

…so the rules of the Tang Dynasty were not territory scoring but territory counting, the counting method being stones scoring

("we use scoring to refer to the definition of score. The point is to distinguish it from the actual procedure used to find the score, referred to as counting, [SL]")

"Stone Scoring" = katago ancient-territory

The wrong score result under katago stone-scoring is due to the katago stone-scoring does not meet "equal stones, [CZ]" requirement. So, ancient (with "equal stones") "Stone Scoring" != katago stone-scoring.