Any functional difference between AGA and Chinese on OGS?

OGS Development
1

I’m familiar with AGA rules and how you’re playing an Area game but you can score with both Area and Territory style, but I noticed that it defaults to Area scoring, and there’s no option to present it as the AGA territory scoring instead (I just think it would be visually cleaner in the end game stone removal to look at it the same way you would IRL)

So because of that, is it really just functionally identical to Chinese on OGS? Or does it handle the handicap system differently?

3 Likes
2

Welcome.

Yes. Handicap placement is different. On AGA rules handicap stones placed at fixed positions as on JP rules. But on Chinese rules handicap stones are placed by player.

On AGA rules each premature pass cost 1 point.

On Chinese rules game is ended after any 2 consecutive passes. On AGA rules game is ended after 2 consecutive passes with the last pass of white player. (For example sequence of passes wbw, totally 3 passes)

Here is the comparison matrix Play Go at online-go.com! | OGS

5 Likes
3

Thanks! I believe I read on another thread that on OGS it’s not even tracking the prisoner passing stones since that only matters for territory counting, and it’s only scoring area style. But the handicap system is a difference for sure!

4

Yes. But premature pass is always have a cost on any ruleset. On AGA rules it is implicitly stated.
You should pass at the right moment.

1 Like
5

So about this matrix, what are the rules exactly? Are they the rules OTB or are they are their adaptation on OGS?

If it’s the first one (OTB rules) then I would be interested in getting the second (OGS proper sets of rules).

1 Like
6

Perhaps this is an accurate summary:

4 Likes
7

So next time my 7 years old friend or my 76 years old one ask me if we deduce the handicap stones from the score of black under Japanese rules on OGS, or if point in seki are counted, I will answer to go check this document?

But nice at least I know where to find the info. Thanks to point where to look exactly.

Note: I wonder if AI could be useful here to translate it into some more readable text

Note: after taking time to read this chunk of code, I didn’t get the answer on my second question about point in a seki. Considering that no parameter are about it, my guess is they are no difference between the rules on this on OGS while there are OTB. Which rules differs from its OTB counterpart is getting over my head but I would suspect the Japanese set.

2 Likes
8

I wouldn’t point a 7 year old to this file, but the code is the source of truth. I do think that section is comprehensible to a layperson. I appreciate you taking a go at it!

Under "japanese" there is this line:

defaults.score_territory_in_seki = false;

So OGS tries to handle it (it’s not always successful AFAIK)

There are other rules like “bent four in the corner” or “triple ko” which aren’t respected. But I think this is more a topic for Odd Cases 🤔 in the Japanese Rules

1 Like
9

Thanks, this is great and confirms the differences for sure. It seems the white passes last feature is just in there for posterity because it doesn’t actually do anything since it is only scoring area style. But the superko algorithm and handicap seems to be slightly different.

1 Like
10

I would not say that these are not respected, but just out of the scope of the implementation, but in different ways:

  1. Determining life and death is up to the players to do, during the scoring phase. It’s largely up to them to figure out how to correctly apply the Japanese rules, and they can call the moderators to help resolve any disputes that may arise.
  2. It seems the OGS does not formally support “No Result”, even though the Japanese and Korean rules are described with the parameter defaults.superko_algorithm = "noresult";. The games are just simply allowed to endlessly cycle and the only workaround is to call a moderator to manually declare the game as a “Tie” and then annul it, since “No Result” is not a supported option.

The Japanese and Korean rules are also listed with the parameter defaults.opponent_plays_first_after_resume = true;, but it seems that OGS does not support that. Resuming the game, just continues with the game order, regardless of who pushes the resume button.

2 Likes
11

Do you happen to know what code may make use of and implement the various superko algorithms, as specified by lines like the following:

defaults.superko_algorithm = "csk";
defaults.superko_algorithm = "ssk";
defaults.superko_algorithm = "ing";
defaults.superko_algorithm = "noresult";

I’m really curious about what the Ing ko algorithm may be. As far as I’m aware, the “csk” (Chinese Superko) implemented on this site is just basic positional superko.

12

I guess code does lie :joy:

Looks like here:

1 Like
13

So to be more accurate, I think the superko rules (as implemented by OGS) should be restated as:

  1. Chinese and Ing Rules
    • positional superko
  2. AGA and New Zealand Rules
    • situational superko
  3. Japanese and Korean Rules
    • simple ko (long cycles are allowed and no results have to be manually handled)
1 Like