New Concise Rules
Inspired by Tromp Taylor attempt at very short rules, these are significantly shorter (62% the size) and hopefully at least as clear without the need for much commentary.
The goals of their rules and mine are much different. T/T attempts to be precise enough for machines, and relies on commentary to make the essential rules more recognizable as the game we know. These rules are supposed to be precise enough for humans, describe the game as closely as possible to how its played, effectively define and use some critical terminology, and do it all in the very fewest number of words (as a challenge).
I have accepted some of Robert Jasiek's thoughtful criticisms, leaving prior language still visible in the in the comments with pseudo s̶t̶r̶i̶k̶e̶t̶h̶r̶u̶ text.
1. The board features a grid of vertices (typically 19x19), called points.
2. Two players, Black, then White, alternate placing eponymously-colored stones on empty points.
3. Same-colored stones connected by grid lines form groups, whose liberties are directly connected empty points.
4. Player concludes move by removing opponent's liberty-less groups.
5. No move may leave one's own group without liberties.
6. Repeating a board position is illegal.
7. A Player may pass his turn.
8. Play ends when both players pass and agree on removal of non-viable groups.
9. Each player scores points occupied by his groups, plus "empty groups" connected only to his color.
RobertJasiek: Points is badly chosen because of confusion with the scoring unit; use intersections. Connected is under-defined; you mean something like continuously connected along grid lines. Group is badly chosen because of its different strategic meanings; say string or chain. Self-capture is undefined. Board position is undefined. The moment of repeating (after completion of a move) is undefined. Non-viable is undefined. The case of disagreement is undefined. Empty group is undefined because group is defined from stones. Touching is undefined and unnecessarily introducing another term; use directly connected instead because of having used it before. However, directly connected is undefined; define it as adjacent via a grid line; but why then not just use the latter wherever applicable? In summary, you are trying to reinvent the wheel. When spelling out everything, you are not shorter than Simple Rules or Tromp-Taylor. Since you use area scoring, the term prisoners is superfluous; simply say removed.
Points is badly chosen because of confusion with the scoring unit; use intersections.
The points on the board are the very same things we are counting when scoring. Some are yours, and some are mine. So that was a purposeful and good choice, IMHO.
Connected is under-defined; you mean something like continuously connected along grid lines.
The intersections on the grid are clearly connected to one another by grid lines. If stones are connected by lines they are connected. Otherwise they aren't.
Group is badly chosen because of its different strategic meanings; say string or chain.
I've personally never cared for the geeky terms strings or chains, which to me imply purely linear constructs. (Visualize a string or a chain -- do you see what I mean?) I don't see the issue with different strategic meanings. It is a viable meaning, and the only meaning I am employing in the context of the rules.
5̶.̶ S̶e̶l̶f̶-̶c̶a̶p̶t̶u̶r̶e̶ i̶s̶ i̶l̶l̶e̶g̶a̶l̶.̶
Self-capture is undefined.
(Subsequently amended) You are right, I'm unhappy with it too, so perhaps I should have held off offering these rules until I had something better. It was a casualty of the bravado of the attempt at extreme brevity.
Board position is undefined.
Right again, but then I have seen that exact undefined expression used before in rules, haven't I? And I never had difficulty grasping the meaning, so I also treat it as self-evident.
The moment of repeating (after completion of a move) is undefined.
I don't see how that is necessary. Could you show me how the rule could be misconstrued?
Non-viable is undefined. The case of disagreement is undefined.
I grant you non-viable. I don't know what you mean by 'the case of disagreement is undefined'. I believe these rules succinctly and strongly imply that if both players pass, and they agree on how the game is to be scored--whose points are whose--then play ends, otherwise they may just continue playing until they both pass and agree.
Empty group is undefined because group is defined from stones.
Admittedly this is a stretch,--but a very small one, IMO--from defining groups. But since we all understand points are either empty of contain black or white stones, I felt comfortable throwing in the term empty groups as a graspable concept in the context of the previous definition of groups.
Touching is undefined and unnecessarily introducing another term; use directly connected instead because of having used it before. However, directly connected is undefined; define it as adjacent via a grid line; but why then not just use the latter wherever applicable?
Ok, I can (and have) throw out touching, but why do I need directly connected. I have already defined connected and it could be reused here too, no?
In summary, you are trying to reinvent the wheel.
Guilty as charged. That was the whole point. And while it could be improved, I'm not yet dissuaded of the value of my attempt.
When spelling out everything, you are not shorter than Simple Rules or Tromp-Taylor.
I actually thought I covered more ground than Tromp-Taylor, with a common touch, and without a real need to resort to recursive language.
4̶.̶ A̶f̶t̶e̶r̶ e̶a̶c̶h̶ m̶o̶v̶e̶̶, l̶i̶b̶e̶r̶t̶y̶-̶l̶e̶s̶s̶ o̶p̶p̶o̶s̶i̶n̶g̶ g̶r̶o̶u̶p̶s̶ a̶r̶e̶ r̶e̶m̶o̶v̶e̶d̶ a̶s̶ p̶r̶i̶s̶o̶n̶e̶r̶s̶.
Since you use area scoring, the term prisoners is superfluous; simply say removed.
(Subsequently accepted) I added the two words as prisoners, since it is still a useful term to know, even if one uses area scoring. I could have defined territory scoring as easily, if you would grant me my definition of empty groups.
I like the fact that these rules simultaneously introduce and define useful terms with so few words. Too few, evidently, due to at least the defects I have granted. I do hope to fix that, but I honestly believe I have also made a fair set of defensible choices. Thank you for giving them your consideration.
RobertJasiek: I lack time to continue discussing each detail so here are only the non-obvious replies:
- Rules are meant to be applied. One application is strategy. There confusion does arise between group = string and group = set of strings, which might be one or several strings.
- Repetition without definition: Placing the stone on the board seems to create (which might be a fake recreation of) a position, already before execution of any removals.
- Agreement: You claim consise rules so why do you use agreement at all?
- Disagreement: If you mean "they may just continue playing until they both pass and agree", write it in the rules.
- Prisoners: If it is a useful term to know, then, with the same argument, there are 100,000 further useful terms that could be in the rules. IOW, usefulness of a term is insufficient justification for anything to be in the rules.
- These rules are meant to be applied to a basic understanding of the game. The implications of the rules, elegant or otherwise is vast, as we all know, and I cannot conceive of why you bring strategy into play here to make demands on the terminology of the rules.
- Yes, your loophole is technically a possible misunderstanding, but it is not a plausable misunderstanding, nor can I picture such a case of repetition even if I would grant you that misunderstanding. However, I modified the language to say Player concludes move... which I believe is sufficient explanation for heroically concise rules.
- Can't understand at all what you mean about agreement. Agreement is essential to scoring the game.
- Disagreement: If you read the words Play ends when both players pass and agree on removal, it should be evident that if they do not both pass and agree, then play does not end, in which case they are still playing until they do both pass and agree.
- Yes, we could kill two words. (I did.) However, if you play a game on most any Go server--irrespective of rule set you use--you will see the status maintains a count of prisoners. It definitely is not 'by the same argument' like any of your 100,000 further useful terms, since it still relates to the end result even if you score by area. An account of your removed stones deserves to called something, since their removal increases the burden on your remaining stones competing for control of more area. (And please don't bring up handicap games).
RobertJasiek: See my rules webpages for the difference between simple area rules and agreement area rules; since you know Tromp-Taylor, you should also know that agreement is superfluous / an optional extension to rules. Rules must not be guesswork of what to possibly interpret into them implicitly (I spent over a decade to decrypt such rulesets, so I do know) but must be clear; therefore, do not hide an implicitly meaning of the game not having ended without agreement. By introducing a concept of two-dimensional end condition (both pass AND agree), the rules are not concise, as their title claims. Go server convenience is not the task of a ruleset. Removal is clearer than capture. As you can see on my rules webpages, handicap would not come from me because I classify it among tournament rules.
RobertJasiek: I suggest these definition-avoiding concise rules:
1. The players alternate until successive passes.
2. Playing removes any opposing stones without liberties, creates stones with liberties and a new position.
3. The winner occupies or surrounds more intersections.