Statistically derived komidashi?

[HermanHiddema]

I think we also have enough data for 7½ komi. Does some one have them at hand and be able to tell whether black still has an advantage? If yes, then we would need, say 1000 games with 8½ or preferably 9½ to know better.

At http://senseis.xmp.net/?Komi%2FStatistics there is a section I posted about 7.5 or 8.0 (Ing) komi, which has white winning 50.5% of games in a sample of 410 games from gobase.org where both players are at least 8d pro.

[hyperpape]

Addendum:
Supposing that 7 is, in fact, the correct komi. Would it be worth allowing Jigo again to make the game fairer?

A good question, and I think you can make an argument that draws should be possible in some ideal sense. But if komi suffices to reduce the advantage to less than a 52% win percent (for either White or Black), that's excellent balance. I don't find it worth tolerating a 5% chance of draws in competition to remove that advantage. Perhaps if it were the old days in which a series could continue as long as it needed, that would be ok, but we already have scheduling conflicts.

(Btw: even allowing draws would not necessarily make the result 50-50. We could be talking about moving the needle by less than 2% advantage to a point that is still slightly unbalanced).

[HermanHiddema]

Supposing that 7 is, in fact, the correct komi. Would it be worth allowing Jigo again to make the game fairer?

Depends on the circumstances. If would theoretically be fairer, but might have other downsides.

In round-robin leagues it would not have any real downsides.

In Swiss/MacMahon it would work, but introduce slightly more up/down pairings due to the rarity of players with half points.

In knock-out it could break the system (but see: ResolvingJigoByKoThreats)

[ez4u]

I think we also have enough data for 7½ komi. Does some one have them at hand and be able to tell whether black still has an advantage? If yes, then we would need, say 1000 games with 8½ or preferably 9½ to know better.

At http://senseis.xmp.net/?Komi%2FStatistics there is a section I posted about 7.5 or 8.0 (Ing) komi, which has white winning 50.5% of games in a sample of 410 games from gobase.org where both players are at least 8d pro.

I am not sure why you think that 8p both sides is particularly relevant in the present pro environment (consider who gets excluded from the results). Anyway my copy of GoGoD (summer 2013) has 9,340 games with komi of 3.75 (i.e. Chinese rules with 7.5). White wins 52.3%. The not quite 19,000 games with komi of 6.5 have Black winning 50.2%

[HermanHiddema]

I am not sure why you think that 8p both sides is particularly relevant in the present pro environment (consider who gets excluded from the results). Anyway my copy of GoGoD (summer 2013) has 9,340 games with komi of 3.75 (i.e. Chinese rules with 7.5). White wins 52.3%. The not quite 19,000 games with komi of 6.5 have Black winning 50.2%

Is the weaker player (lower pro rank) more likely to get black in that sample? I wanted to avoid that option.

[shapenaji]

A good question, and I think you can make an argument that draws should be possible in some ideal sense. But if komi suffices to reduce the advantage to less than a 52% win percent (for either White or Black), that's excellent balance. I don't find it worth tolerating a 5% chance of draws in competition to remove that advantage. Perhaps if it were the old days in which a series could continue as long as it needed, that would be ok, but we already have scheduling conflicts.

Chess gets by with far more draws than I think we'd ever have, I feel like competitions could probably handle it.

(Btw: even allowing draws would not necessarily make the result 50-50. We could be talking about moving the needle by less than 2% advantage to a point that is still slightly unbalanced).

Certainly, If the exact 7 pt komi doesn't make the results closer to 50-50, then there's no point. It's just interesting that we have limited our calibration to only adjusting komi by a full point, rather than a half point.

[oren]

Certainly, If the exact 7 pt komi doesn't make the results closer to 50-50, then there's no point. It's just interesting that we have limited our calibration to only adjusting komi by a full point, rather than a half point.

I don't think we'll see that change in professional play. Sponsors and tournament directors want a winner and loser. Having to do repeat games can be a bit annoying.

[ez4u]

I am not sure why you think that 8p both sides is particularly relevant in the present pro environment (consider who gets excluded from the results). Anyway my copy of GoGoD (summer 2013) has 9,340 games with komi of 3.75 (i.e. Chinese rules with 7.5). White wins 52.3%. The not quite 19,000 games with komi of 6.5 have Black winning 50.2%

Is the weaker player (lower pro rank) more likely to get black in that sample? I wanted to avoid that option.

There are no events like that AFAIK. There are a few special events like the new-shodan games each year in Japan, but they do not use the standard komi.

[hyperpape]

Chess gets by with far more draws than I think we'd ever have, I feel like competitions could probably handle it.

Perhaps you just mean to say that the low proportion of draws in Go would be ok, but comparisons to Chess don't make the point. There is a large and vocal contingent of people complaining about the frequency of draws in high level play, and there have been proposals to change the rules to reduce the number of draws.

[lemmata]

Assume that

• the players do not resign but always go to counting
• non-counting draws (due to triple-ko, etc.) do not occur
• black wants to maximizes black territory minus white territory
• white wants to maximizes white territory minus black territory

Under perfect play, some player (presumably black) always wins by K points with no komi.

Suppose that, as the skill of the players approaches perfection, the probability of black winning by K points approaches 1. Then

• Under a komi of K+0.5, the probability of white winning by 0.5 approaches 1 as the players approach perfection.
• Under a komi of K-0.5, the probability of black winning by 0.5 approaches 1 as the players approach perfection.

This seems like an irrelevant mathematical oddity because perfect play is so far off. However, suppose we assume symmetric probabilities (without komi) for Black winning by (K+n) and Black winning by K-n.

Then all we need for White to win 50+x% of the time (with komi=K+0.5) is for the probability of Black winning by K (without komi) to approach 2x%, which is a far cry from 100%. Pros can easily keep any game from getting beyond a 10 point difference with the current komi if they don't care about winning. That actually seems like a conservative estimate if we believe that any top 20 pro could win 90%+ of the time if he was taking black with no komi.

What is the conclusion here? A stable non-integer komi that produces 50-50 outcomes is not a realistic long-term goal. It may be achievable in the short term though.

I could see komi cycling between two values as players research black's fuseki when komi=K+0.5 and research white's fuseki when komi=K-0.5. In the long-run we will either have to keep changing komi every once in a while or switch to a system that allows ties.

[lemmata]

Addendum: The SG Pair Baduk tournament uses a system called "dum betting" (komi betting). Each team secretly writes down a komi value on a piece of paper. The team that wrote down the higher komi value takes black and offers that komi. In the case of a tie, they use nigiri to see who goes first. Such a system, if adopted for one-on-one pro games, may obviate the need to adjust komi values via arduous bureaucratic processes long after the winning percentages get out of hand.

[shapenaji]

Chess gets by with far more draws than I think we'd ever have, I feel like competitions could probably handle it.

Perhaps you just mean to say that the low proportion of draws in Go would be ok, but comparisons to Chess don't make the point. There is a large and vocal contingent of people complaining about the frequency of draws in high level play, and there have been proposals to change the rules to reduce the number of draws.

Well, they certainly argue about the frequency of draws, but not their existence. I think most chess players are fine with the possibility of draws, they just don't like that top players have methods at their disposal to ensure draw-like games. I don't think go lends itself to a drawing strategy in the same way.

[Bill Spight]

Chess gets by with far more draws than I think we'd ever have, I feel like competitions could probably handle it.

Perhaps you just mean to say that the low proportion of draws in Go would be ok, but comparisons to Chess don't make the point. There is a large and vocal contingent of people complaining about the frequency of draws in high level play, and there have been proposals to change the rules to reduce the number of draws.

Well, they certainly argue about the frequency of draws, but not their existence. I think most chess players are fine with the possibility of draws, they just don't like that top players have methods at their disposal to ensure draw-like games. I don't think go lends itself to a drawing strategy in the same way.

Wasn't there a flap several years ago about an arranged draw (or no result) in a go tournament?

[shapenaji]

Wasn't there a flap several years ago about an arranged draw (or no result) in a go tournament?

Have a handy link?

I think that's the big difference though, in chess it doesn't take collusion to force a draw with high probability (as white).

[SmoothOper]

Chess gets by with far more draws than I think we'd ever have, I feel like competitions could probably handle it.

Perhaps you just mean to say that the low proportion of draws in Go would be ok, but comparisons to Chess don't make the point. There is a large and vocal contingent of people complaining about the frequency of draws in high level play, and there have been proposals to change the rules to reduce the number of draws.

Well, they certainly argue about the frequency of draws, but not their existence. I think most chess players are fine with the possibility of draws, they just don't like that top players have methods at their disposal to ensure draw-like games. I don't think go lends itself to a drawing strategy in the same way.

I think the rules in chess encourage draws, by allowing repeated states, though it is difficult to keep track of the repeated states in casual settings since chess has so many configurations with the same set of pieces, however if they had a super ko type rule, they wouldn't have this problem.