New Zealand Rules Are Actually Closer To Tromp-Taylor

OGS Development
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Note: I created this thread hoping a developer might be able to answer my questions. Thanks to users and good old fashioned research, all of my questions have been answered. I have now rewritten this first post to reflect the knowledge gained, since no questions need answering any longer.

 

I recently learned about NZ rules when I did research to outline the differences between New Zealand and Chinese Rules here on the forum. I was curious which parts of the Official NZ rules were faithfully implemented in OGS’ New Zealand ruleset. The threads below show my journey to find answers. What follows is the answer:

Official New Zealand Ruleset

  1. Komi: 7
  2. Draws: Possible
  3. Suicide: Allowed
  4. Game Position Repeat: Situational Superko
  5. Game Conclusion: Player Agreement
  6. Handicap: No point compensation

 
OGS Implementation of New Zealand Rules

  1. :x: Komi: 5.5
  2. :x: Draws: Not possible on OGS
  3. :white_check_mark: Suicide: Allowed
  4. :x: Game Position Repeat: Positional Superko (proof)
  5. :white_check_mark: Game Conclusion: Player Agreement
  6. :x: Handicap: No point compensation (proof), No Komi

The reason that I was curious is because my new favorite ruleset is Tromp-Taylor. I remember feeling disappointed when I discovered the ruleset, while researching New Zealand, and it wasn’t represented on OGS. For those who aren’t aware, there are only two rule differences between Tromp-Taylor and New Zealand rulesets. They are:

  1. Game Position Repeat: Positional Superko
  2. Game Conclusion: Two successive passes (Official TT) ║ Player Agreement (Amended TT)

It dawned on me a few days ago that OGS’ New Zealand rules implementation might closer to Tromp-Taylor. So I began searching for answers. This is how official Tromp Taylor rules look and I’ve added the X’s and Checkmarks to reflect how those rules are implemented on OGS.

Official Tromp-Taylor Ruleset

  1. :x: Komi: None; Player Agreement
  2. :x: Draws: Possible
  3. :white_check_mark: Suicide: Allowed
  4. :white_check_mark: Game Position Repeat: Positional Superko
  5. :white_check_mark: Game Conclusion: Two successive passes (Official TT) ║ Player Agreement (Amended TT)
  6. :white_check_mark: Handicap: No point compensation

As you can see, thanks to Game Position Repeat and Handicap, Tromp-Taylor is a closer fit to OGS’s current implementation of NZ rules. Now it is small enough that I doubt anybody cares and up till now nobody has noticed. I don’t expect OGS to change the name of the New Zealand ruleset, but as an ardent advocate for Tromp-Taylor rules, I have to point this out :hugs:.

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Possibility of jigo is also a thing that OGS doesn’t implement properly :<

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That is a very good point. I’ve updated my post to reflect that. Thank you _KoBa :wink:.

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Is there a typo here? I thought OGS would have used a stone agreement phase, like it does for the other rules (however, I don’t know, since I haven’t actually played with NZ rules on OGS before).

It should also be noted that a practical amendment to the Tromp-Taylor rules is to also incorporate a life/death status agreement phase in order to avoid the burden of making extra moves just for capturing dead stones at the end. These are mentioned in the commentary part of the Tromp-Taylor rules.

Technically, komi is also another point of difference between the rulesets. NZ rules mandate a komi of 7, while Tromp-Taylor rules (only mentioned in the commentary) leaves that choice flexible to be arranged by prior agreement by the players.

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Whoops. Yes, that checkmark should in fact be a big red X. I have played NZ rules on OGS many times, and the end phase is identical to the way other rulesets handle scoring.
 
 

 
The rules state:

This is weird. I’m not sure that I understand it. Is it saying that a game requires 4 consecutive passes to end? You can pass twice and come to an agreement on which stones are dead, OR you continue to play until four consecutive passes occur? My previous statement that the rules called for two consecutive passes to end came from the Sensei’s Library page for the TT rules. I found some commentary by Robert Jasiek about the TT rules, and his explanation also states that two consecutive passes ends the game.
 
 

Indeed, Komi itself seems to be entirely optional. The way that the rules are worded makes it seem like Komi isn’t actually a part of the rules at all. The only time Komi would occur is if both players agree that it is needed, and then upon what the value should be. Once again, my previous statement that Komi was identical between NZ and TT rulesets related to the commentary for the TT rules on the Sensei’s Library TT rules page.

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I think the main motivation for the core Tromp-Taylor rules is to be as concise as possible while capturing the essence of the game, as needed for a programmer or game theorist.

In the core rules, the game ends (and all stones left on the board are considered alive) immediately after two passes. Thus, playing strictly by these rules, the players should continue playing until they’ve captured all of their opponent’s dead stones, if they want to optimize the score margin in their favor. Of course, in practice, a player could resign earlier upon realizing that they are losing.

However, it’s quite cumbersome to actually play out a strategically meaningless clean-up phase, just for removing your opponent’s dead stones, so in the commentary of the TT rules, they propose the following. Here’s how I interpret it:

  1. After two consecutive passes, the game enters a stone confirmation phase.
  2. During the stone confirmation phase, the players discuss which stones on the board are dead and should be removed.
  3. If they agree, then they remove those dead stones, play ends, and they count the score.
  4. If they disagree, then they continue playing (leaving the stone confirmation phase).
  5. They play until they have made four consecutive passes.
  6. At that point, all stones remaining on the board are considered alive, and they count the score.

I think the point of four passes in a row is that if after step 4, two more passes are immediately played (i.e., no player wants to make another move) then the game can end immediately. Also, I think it might help clarify the finality of four passes as stopping dispute over which stones are dead.

Forcing the game to immediately end after four consecutive passes prevents a player in a strategically losing position from delaying the game from ending forever. Although the losing player can drag out a game for a very long time, they will eventually be force to make passes, when they run out of legal moves, since single-stone suicide is not permitted, and they must have eventually run out of larger groups to sacrifice by filling their own eye space.

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For clarity, these are what the three scenarios for ending the game, using the TT amended rules, look like:

Scenario Setup

  1. Normal gameplay is underway
  2. Black Passes
  3. White Passes

 
Scenario 1: Players Agree About Dead Stones

  1. Agreement Phase (AP) begins
  2. Players agree on dead stones (even if takes multiple APs to agree)
  3. Score is tallied and game ends

Note: John Tromp explains that when players enter an AP and decide to resume play, the game proceeds as if no AP ever existed. It doesn’t matter how many times players enter the AP during a single match. The game history should only ever reflect that the players entered an AP a single time.

 
Scenario 2: Players Unable To Reach Agreement

  1. Agreement Phase begins
  2. Players do not agree about dead stones
  3. Agreement Phase is over, like it had never existed, and gameplay resumes
  4. Since Black made the first of two passes, it’s Black’s move again. If Black refuses to move or pass, then Black will eventually forfeit because turn time will run out. To speed things up, Black could just choose to resign.

 
Scenario 3: Four Successive Passes Occur

  1. Agreement Phase begins
  2. Players do not agree about dead stones
  3. Players agree to resume gameplay
  4. Agreement Phase is over, like it had never existed, and gameplay resumes
  5. Black decides to not play after all, Passes
  6. White decides to not play either, Passes
  7. Score is tallied and game ends (no stones are removed, all stones considered live)

 
@yebellz
I tip my hat to you yebellz. I tried to analyze the rules critically and I wasn’t 100% sure that your interpretation of them was accurate. It made sense to me but I felt there was enough ambiguity to warrant further research. I reached out on /r/baduk and received responses, but they did not mirror your explanation. With sufficient doubt I reached out to John Tromp himself, and he answered my questions directly. His responses confirm that your interpretation is 99% accurate. I tip my hat to you, because that is a lot farther than my interpretation got me :blush:.

Concerning the differences, he stated that before gameplay begins, the players should agree upon utilizing two consecutive passes or the player AP. It is not a case of “if there is a dispute, go ahead and activate the player AP.” I actually prefer this as it prevents another vector for disagreement (arguing over how the game ends, two passes vs an AP). However, I can’t imagine why human players would ever decide to not utilize the Amended rules. So, this feels like a moot point. But still, that’s the official ruling regarding how the Amended rules fit into the Official Rules picture.

Concerning the uncertainty of how a game concludes, on your numbered list #5 states they play until they have made four consecutive passes. Mr. Tromp explains that to achieve four consecutive passes, both players would have to pass immediately after leaving the player AP. So the above Scenario #3 is what four passes looks like in a real world example. So it looks like my original post had it right the first time around.

The list item “:x: Game Conclusion: Two successive passes” should in fact be a :white_check_mark:. OGS currently utilizes the amended TT rules Agreement Phase. New Zealand also uses the AP. So for now, the :white_check_mark: is deserved. However, once OGS’s code for game score evaluation is perfected, the game will then use the Official TT rules two successive passes rule to conclude the game. Were that to happen, an :x: would be deserved. So I’ve edited that in the original post.

Now I just need to figure out how OGS’ NZ ruleset handles Superko and how it awards points for handicap games. Handicap should be easy enough to find out, but I think we’ll need to hear from an OGS Staff member to learn about Superko. I’ve created a new post asking that singularly specific question. Hopefully someone will respond soon :hugs:

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I am finishing this thread up with the final bits of information needed to fully understand how New Zealand rules are implemented on OGS. The two topics that remain uncertain are, 1) Game Position Repeat, and 2) Handicap.

Game Position Repeat
Does OGS’ implementation of NZ rules utilize Positional Superko or Situational Superko? I’ve proven, without a doubt, that New Zealand utilizes Positional Superko here on OGS. Actual NZ rules utilize Situational Superko.

 
Handicap
New Zealand rules do not award any point compensation for Handicap stones. For comparison, under Chinese rules Black gives White compensation for handicap stones, so that the area which they occupy is not counted. But under NZ rules, no such compensation is given. The rules also specifically state that Komi is not to be used.

To test this I played a match and gave Black 10 handicap stones.The final score for White reflects that no points were added to White’s score to account for handicap stones. However, if you mouse over the Captures text for White, you will see that it says it awards 10 points for Handicap. Despite it showing this, no points are actually reflected in the scoring. This Handicap data is shown for all OGS games, despite what ruleset being utilized. However, White is afforded 0.5 Komi. I realize that this was done specifically to avoid ties on OGS, but it is worth mentioning as it deviates from the No Komi NZ rule specification for handicap matches.

 

Note: I created this thread hoping a developer might be able to answer my questions. Thanks to users and good old fashioned research, I've answered all of my questions and have now rewritten the first post to reflect the knowledge gained, since no questions need answering any longer.

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I don’t think the TT rules suggest 7 or any other value for komi. They mention 5.5 in the commentary, but that seems to be only an example, rather than even a suggestion.

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Arg, I think New Zealand and Tromp-Taylor got mixed up like ice cream flavors in my head. Thank you for pointing that out. It has been fixed. You are awesome yebellz :star_struck:

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I’ve updated the original post, OGS Implementation of New Zealand Rules, to reflect that Handicap is not properly observed. On OGS White is afforded 0.5 Komi (proof). I realize that this was done specifically to avoid ties on OGS, but it is worth mentioning as it deviates from the specific No Komi rule for New Zealand handicap matches.

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