I think you're misunderstanding what I'm saying. All I was trying to say in the post you quoted was that the loser of a go game where both players understood the value of komi beforehand (regardless of whether or not it is 0 or a non 0 value), then the loser didn't play perfect moves. The reason I'm saying that is because if there is a loser, than the moves the loser played simply weren't as good (i.e. didn't make as many points or didn't attack a group) or better than the moves his/her opponent played. If they were, then that person would have won the match.

I would also like to clarify that my argument (I think) would hold up regardless of whether or not perfect play is possible. You don't need to play perfectly to beat your opponent, you just need to play better moves then him. It is also hard with our current understanding of go to say that there is such a thing as perfect play. By the time endgame rolls around then there is definitely a way to play perfectly, but in the opening it is hard to say that there is such a thing as perfect play. Maybe in the future we will find out that perfect play is possible, but as things are right now I think it would be a bit to presumptuous of us to say that perfect play is possible. But, for the time being, I don't really think that playing perfectly matters for this discussion, since we don't even know if perfect play is possible.

I hope this clarified what it was I was trying to say.

moboy78, saying that perfect play exists is not the same thing as saying that we can compute it: it is quite clear that perfect play exists. (For simplicity assume super ko so the number of possible go games is finite. Then look at the whole tree of all possible games, start at the final positions and just backtrack all the way up to the empty board, recording at each node one of the optimal moves.)

I understood you, i think you didn't understand my post here.
Since we neither know the perfect komi value or the perfect play, this is all a hypothetical argument. But these are good to find logical flaws in arguments. And if i use this approach on your conclusions, then perfect play is impossible if the komi is x.5

The number of possible board situations is finite and so is the number of possible moves for each player with a given board position. With super ko it is ensured that each sequence of plays does end at some point.
The komi is a theoretic perfect komi x.
We assume that at every position there exist an optimal move for the current player, the move that maximizes his point potential and minimizes the point potential of the opponent. Both players use the same metric to find this best move.
This metric M is dependant on the komi-value x, which is what you stated. Komi has to be taken into account while playing. Depending on M and x, there is game-result R. So M is a function of x leading to a game-result R (Winning margin for black). This can be stated in the following form:
M(x) = R
Now we solve this for x, given R=0 (jigo). This x' is the theoretic perfect komi, under which perfect play results in jigo.

Now lets put x'.5 into the equation. Since the game is sure to end at some point there is a clear result R'. Because of the 0.5 in the komi this R' can not be 0, so there is a clear winner. There are two possibilities:
R < 0 - White wins. By your argument this means black did not play perfectly, that means didn't follow M during the game. But he did, so this is a clear violation of the beginning assumption (both players play perfectly), so this can not be the case.
R > 0 - Black wins. The same argument as for black can be now made for white. So we have clear contradiction. Assuming both players play perfectly and assuming there exist a perfect komi x' which leads to jigo under perfect play, a contradiction occurs by your argument (that loosing = not playing perfect).
I think there are three posibilities how we can solve this contradiction:
M - Can there be a single function, depending on komi, leading to an optimal game-result? Since, like Sennahoj said all games are finite and the number of moves are finite it is possible. It may not be computable, bit it exists. (An optimal game-result would here be the minimum R.)
x' - Does a perfect komi exist, that would lead to jigo under perfect play? I think this is debatable. Since we don't know the whole game-tree it might be possible that at some point a branch can be selected, after which no jigo exists. This however would mean the game is inherent unfair, regardless of the 0.5 komi. I don't like to assume this.
Losing under perfect play is possible if komi includes 0.5. Assuming this is much more natural for me. For one, komi is awarded to white to compensate the advantage of the first move. And since all points are counted as whole numbers i find it hard to see how a player can gain a 0.5 lead, if komi is a whole number. So the advantage of the first move would also have to be a whole number (the lead black gains by playing first).
There a situations where the average value of a move might be a fraction because it takes several moves to gain a single point, but the actual lead is still whole, because either the player gains that point or he doesn't, he can't gain 0.5 points.

So from my point of view - yes a .5-komi is unfair but only if we have arrived at the optimal x'.5 komi. I don't think we have and if we had we would see white winning most of the time in pro games - then it would probably adjusted to x', even if this would mean more work handling jigos in tournaments.

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Not sure I understand this point. If it really means what I think it does, then I think I disagree. I am slightly confused here, heh...

Here is what I have an issue with:

1.
Assuming in every position an optimal play/move exists, which maximizes the player's score and/or minimizes the opponent's score (point potential?), I don't see why it is dependent on komi. Either a move is the largest on the board, or it is not. Either it reduces the most, or it does not. Either it results in the most points gain, or it does not. Komi of 6.5 or 7.5 does not change this. Komi can influence if the largest move is also a winning move, but it cannot change the fact that a move is the largest or not. Just like the current score does not determine the objective value of the move, it just influences if the largest move is also a winning move. Substitute "optimal" or "perfect" for "largest" and you will get my point.

2.
You are correct that in practice "Komi has to be taken into account while playing" - but this is precisely because we do not know the best play. Just like the current score has to be taken into account. It allows us to make strategic decisions of the sort "do I play safely" or "do I need to invade" or some such, based on the fact that we are behind or ahead in the game. It has really nothing to do with the fact if any given candidate move is objectively the most perfect/gainful or not.

Or am I too confused and misunderstand what you trying to say?

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WARNING: This post might contain Opinions!!

I don't like the idea of the half point to begin with because it just seems unnatural. I mean, there are no "half-points" on the goban. Theoretically, a specific move might gain a fraction of a point, however, when it's all said and done, there are only complete points ( you can't surround a half of a point).

Furthermore, I never play by area rules so I'm not certain but if I've been told correctly, you still receive points for stones in seki. If this is true, is a draw under area scoring not impossible anyways? Because there are 361 points to be had on the board and if you receive points for dame, then the board can't be split 50-50 (under territory scoring, there may be an odd number of points in dame allowing for a 50-50 split). Thoughts?

Here's the rub (you don't have to read this if you don't appreciate abstract thought): Let's say that komi is unnecessary and that the game is jigo at best play on both sides (best play as defined by me: If God were to sit down at a goban and say "what is the most efficient way that I can place both black and white stones to end up in jigo", His moves would define best play). If this were the case, this means that black, with his first move, has only the potential to make a move that ultimately controls 50% of the board; no more. Now it's white's turn, and the very best move white can possibly make will ultimately lead to controlling the other 50% of the board. This will continue through to the end. Now, because were all humans here (no offense meant if that excludes anyone ), eventually we will make an "inferior" move. That is, a move that ultimately, at best play, leads to controlling less than 50% of the board. For simplicity, let's say 49%. At that moment, for the first time in the game, the opponent now has the opportunity to make a move that ultimately leads to controlling 51% of the board. This is the deep, underlying principle of all proper abstract strategy, zero-sum board games: Only once you're opponent makes a less than perfect move do you have an opportunity to make a winning move.
So, when we talk about komi, the question is: what percentage of the board does white need to start out with in order to achieve a 50-50 split at optimal play. Obviously, this will not be a whole number but will involve a fraction of a point. Therefore, how do you award this "perfect" komi to white without destroying the possibility of jigo and if there's no jigo, the game certainly cannot be called fair for the reasons already discussed. There in lays my question (which obviously has no practical applicability because none of us will ever play perfectly): but! for the sake of getting to think about Go as much a possible, from as many angles as possible , how can it be that in order to make the game fair, white needs a fraction of a point for komi, however, giving white this komi leaves the game un drawable and therefore unfair? It has perplexed me quite a bit as of late. Also, I realize that these are my personal theories; I'm not trying to "teach you guys a thing or two about Go".

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A question though, do you think it'd be a good idea to set komi according to perfect play?

Regarding the 'perfect komi':

Taking the definition of Perfect Play from Wikipedia:
In game theory, perfect play is the behavior or strategy of a player that leads to the best possible outcome for that player regardless of the response by the opponent.

Regardless of the komi, the perfect play starting from a certain board position will always be the same.
Even when the perfect play from that position always leads to a losing game the idea is to minimize the loses (there can be more than 1 move as a perfect move that will lead to the same final point).
This is because the komi is only translating the final outcome uniformly.

If we assume all games has finite moves due to whatever reason (such as superko, no pass, etc to simplify) then the total number of possible games becomes finite.
Now by 'backward chaining' from a certain final position we can get the best outcome (say maximizing black point - white point for black) and therefore the best move from 1 move before the end of game.
Repeating the process for all final position one can get the best outcome from the starting of the game. (this is valid from finite tree)
When this outcome say is 10 (black points - white points) then you get the 'perfect komi' which is always an integer.
Whereby with this value of komi and 2 perfect players they will always force the game to draw. (it can be more than 1 possible games that can lead to this draw I suppose)


Hence, comes the more philosophical question as Boidhre asked.
If the 'perfect komi' of above is used then the game somehow becomes fair to the perfect players.
But does this needs to be used? or is this the same fair criteria to be used?
Is this the value that people are trying to guess using the 'statistical data'?

The second thought is that the statistical data might be pretty far from 'perfect komi' (as previously noted that things can go pretty weird in extreme math)
If we limit the search through statistical komi where all the games is taken from player at best of 10k then the value itself might change (due to more chaotic game)
And hence the komi to be used between two 10k players playing might need to be bigger to be 'fair'. (50% chance of winning at least from the statistics of all games ever been played at this level)

But anyway 0.5 will not really change the result especially for a SDK like me, so no worry on fairness..
Apologize for my craziness..

I would have said smaller, komi presumes you know how to use the advantage of first move and more chaos and big losses makes the value of komi less important if they're equally distributed between black and white, I think the weaker the players are the less it affects game result who goes first. I'd love to see data on this though.

Y'all think too much.

For the time being perfect play is unknowable. I am perfectly content with setting Komi at a level that results in a 50% win level with good, but not perfect play.

If 5.5 yielded a 55% win ratio for black, then it is too low. If 6.5 yielded a 55% win ratio for white, then I'd be content setting at 6.0.

If a new fuseki was discovered that gave black a twelve point advantage, then adjust Komi until that fuseki is refuted.

Sometimes good enough is good enough. The quest for perfection can be our undoing.

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"no half point in go"

I think that this is simply a misunderstanding of the purpose of the half point. It is simply to prevent a tie result. Perhaps it would help if you considered a komi of 6.5 is equivalent to a komi of 6 plus the rule "in case of tie, white wins". Making the komi itself 6.5 eliminates the need for the additional rule. Similarly, in even games, the komi of half a point is simply a rule "in case of tie, white wins". Makes it simpler, just "the player with the most points (including komi) wins". No need for a special rule "in case of a tie count ......."

If you don't like half points how about playing with komi equal to 2π, that's a nice round number.

Actually, there are half points in go. That is, positions that really should count as X + 0.5 points by territory scoring. A move in the position is worth less than filling a dame; in fact, it loses 1/2 point. For instance, in one net play White can move to a position worth 1 point for Black, while in one net play Black can move to a position worth 0. The theoretical value of that position is 1/2 point for Black.

I know that such positions exist, because I have constructed them. Some may have occurred in actual play without being noticed.

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Come on! π are square.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

But that is something different, the "value" of a position. Or the "quantum" points of go. Before the position is played out it can indeed have a fractional value. If we ask "what is the value of some end game position" we have a value if black gets to make the first move and a (different) value if white gets to make the move but at this point we do not know who will have sente when remaining endgame points are down to the size that might attract play here. So we judge the position to be X points with X possibly a fractional value.

But at the time the game is over and being scored, that uncertainty has been resolved, one way or the other, won't be a fraction of a point.

The proper time, in theory, to score a game at territory scoring is when the last dame has been filled and there are no plays that gain points. But what if a play loses 1/2 point for each player? Sure, you can have rules that award an integer score to the position. The J89 rules do. But should they?

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At some point, doesn't thinking have to go on?
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Visualize whirled peas.

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I'm not quite understanding how you claim that fraction points exist. To reiterate, if you use 20 stones to surround 10 points of territory, one way to say it is that each move was worth a half of a point, another way would be to say that each move shared the weight of 10 points. At any rate, by the time you score the board, you will never count up a fraction of a point. But I don't think that's what you meant anyways.

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Thinking like a go player during a game of chess is like bringing a knife to a gun-fight. Thinking like a chess player during a game of go feels like getting knifed while you're holding a gun...

What I mean is this. We may have a board position where neither player wishes to play using territory scoring, because a play makes a loss. That is the normal place to stop play and score the game. The traditional scoring method is to count territory. But there is another way, which we can use to settle disputes, and that is to play an encore in which the player who passes hands over a pass stone as a prisoner and each player makes the same number of plays or passes. Since filling in your own territory costs one point, as does playing a stone inside your opponent's territory, this method preserves integer scores. (Not that it preserves Japanese or Korean scores, but there are rules under which it does preserve scores.)

But there are positions where neither player wishes to play using territory scoring, because a play makes a loss, but where each player wishes to play in the encore described above. The reason is that the loss by territory scoring of making a play is less than 1 point. A play is worth less than filling a dame but more than filling territory. Therefore it loses less than 1 point of territory, and the territory score should have a fractional point.

Here is an example of such a position.



In the encore each player gains 1/2 point on average by playing first so that the value of the starting position is 1/2 point for White. And that is the theoretical territory score for that position.

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At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

I just skimmed the thread and I don't think anyone said it but I'm pretty sure the answer is:

Is black going first really fair?

I was also confused by Bill's claim that half points exist, but now I realize that it's his opinion on what the rules should be, not what they actually are. Unless you use Bill's rules (button go).

It's not as strong a claim as that. If the rules do not allow fractional scores, that's that. But once the idea of button go was around, then I constructed a button on the board.

Suppose that there was a button such that if White took it it would subtract one point from his score, but if Black took it it would leave his score unchanged, and that a player could not pass before the button was taken. Such a button would be worth 1/2 point to Black. That button would be miai with the position shown. That justifies a theoretical value of 1/2 point for White for that position. You can make a similar demonstration of the value of Three Points without Capturing.

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The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.