Fair komi without ties

[pookpooi]

I read my own comment and see many weakness

Let me try again... how about this evidence!

Macelee post the following message on Go4Go forum last year https://www.go4go.net/go/node/54875

I just generated some statistics from Go4Go database. As of today, excluding those few games ending with no results, there are
11256 games with 5.5 komi, of which 5961 (52.96%) won by black and 5295 (47.04%) won by white.
24728 games with 6.5 komi, of which 12507 (50.58%) won by black and 12221 (49.42%) won by white.
15010 games with 7.5 komi, of which 7127 (47.48%) won by black and 7883 (52.52%) won by white.
Apparently the smaller 5.5 komi was too easy for black. The increase of komi around year 2003 was a sensible decision. Unfortunately for China, it doesn't make sense to use 6.5 komi under Chinese counting rule. But 7.5 komi clearly gives white a big advantage. Indeed many top Chinese players (e.g. Ke Jie) prefer to use white.

Since fair is more about perception than mathematics solution, Japanese rule is more fair than Chinese rule. I'm wonder if this is better argument than the last one

PS. If Macelee is reading this, do you have the latest statistics now?
The latest you give is as of 2016-03-08.

5.5 komi: black 6016 (52.84%), white 5332
6.5 komi: black 12830 (50.58%), white 12536
7.5 kimi: black 7215 (47.50%), white 7975

[billyswong]

Unfortunately for China, it doesn't make sense to use 6.5 komi under Chinese counting rule.

The rationale of Chinese counting rule can't use 6.5 komi never make sense to me. Even after reading https://senseis.xmp.net/?WhyChineseKomi ... PointSteps, although it does convince me 5.5 komi and 6.5 komi are "closer" while 6.5 and 7.5 are "wider" under Chinese counting rule, so what? As long as 6.5 komi in Chinese counting rule compensate to white more than 5.5 komi while compensate to white less than 7.5 komi, what makes it so unthinkable as a komi value? Or is it because I am too weak in playing Go so I will never get the mystery of that??

[luigi]

Unfortunately for China, it doesn't make sense to use 6.5 komi under Chinese counting rule.

The rationale of Chinese counting rule can't use 6.5 komi never make sense to me. Even after reading https://senseis.xmp.net/?WhyChineseKomi ... PointSteps, although it does convince me 5.5 komi and 6.5 komi are "closer" while 6.5 and 7.5 are "wider" under Chinese counting rule, so what? As long as 6.5 komi in Chinese counting rule compensate to white more than 5.5 komi while compensate to white less than 7.5 komi, what makes it so unthinkable as a komi value? Or is it because I am too weak in playing Go so I will never get the mystery of that??

There is no reason not to use 6.5 other than the fact that it's virtually the same as 5.5, which has been proven to be less balanced than 7.5.

The reason why 6.5 is virtually the same as 5.5 is that the sum of both player's scores will almost always add up to 361, an odd number, which means that the winner's score will be an odd number of points higher than that of the loser. If Black wins by 5 on the board, they lose with either komi value, and if Black wins by 7 on the board, they win with either komi value.

6.5 komi only gives a different result than 5.5 komi if there is an odd number of empty points in seki, which happens quite rarely.

[HermanHiddema]

Note that 5.5 komi and 7.5 komi are about equally "unfair" according to the statistics. Both are about 2.5% away from 50%.

Under Chinese style rules, if the "correct" komi is 7, then any B+7 on the board should be jigo. In that case, it is logical that 5.5 and 7.5 are about equally unfair, because under 5.5 komi all the B+7 on the board results are awarded to black, while with 7.5 all the B+7 on the board results are awarded to white, and under Chinese style rules B+6 results are very rare (as are any even score results).

So apparently, there is about a 5% zone of B+7 on the board in the middle of the professional stats, and whoever you award those to gets an advantage.

[billyswong]

Herman's explanation further strengthen my suspicion that 6.5 komi may be a reasonable komi value for area scoring, while Luigi's explanation repeated what I learnt from the Sensei wiki I linked.

6.5 komi may be less "fair" than 7.5 komi, maybe not. But assuming 6.5 komi is exactly as fair/unfair as 5.5 komi sounds strange, as professionals fine tune their game play in accordance to komi value, maybe 6.5 komi games will contain seki more often? If statistics really shows that 5.5 and 7.5 are about equal, as said by Herman, there's a chance, however slight, 6.5 may be fairer.

[pookpooi]

We've to get stats on how much 6.5 komi makes different outcome than 5.5 komi.

From stat we've now 5.5 komi has 2.84% deviate from 50% and 7.5 komi has 2.50%
If 6.5 komi affect only 0.1% than 2.84-0.1 = 2.74% which is still more deviate than komi 7.5. So komi 7.5 is still 'more fair' in this sense.

But of course, the real work (if Weiqi Association really want to change komi again) will be much more complicated than my math.

[luigi]

We've to get stats on how much 6.5 komi makes different outcome than 5.5 komi.

From stat we've now 5.5 komi has 2.84% deviate from 50% and 7.5 komi has 2.50%
If 6.5 komi affect only 0.1% than 2.84-0.1 = 2.74% which is still more deviate than komi 7.5. So komi 7.5 is still 'more fair' in this sense.

But of course, the real work (if Weiqi Association really want to change komi again) will be much more complicated than my math.

So no chance for 7 plus button, huh?

[HermanHiddema]

Herman's explanation further strengthen my suspicion that 6.5 komi may be a reasonable komi value for area scoring, while Luigi's explanation repeated what I learnt from the Sensei wiki I linked.

6.5 komi may be less "fair" than 7.5 komi, maybe not. But assuming 6.5 komi is exactly as fair/unfair as 5.5 komi sounds strange, as professionals fine tune their game play in accordance to komi value, maybe 6.5 komi games will contain seki more often? If statistics really shows that 5.5 and 7.5 are about equal, as said by Herman, there's a chance, however slight, 6.5 may be fairer.

The reason I said 5.5 and 7.5 are "about equally unfair", is because theoretically, if 7 is the perfect komi, then 7.5 and 6.5 are "exactly equally unfair", because they exactly award the perfect jigo games to one player or the other. However, the difference between 5.5 and 6.5 is so small under area scoring, that it doesn't really matter if you use 5.5 or 6.5, the difference between those is negligible.

So is 6.5 a reasonable value? Yes, as reasonable as 7.5.

Or 5.5 or 8.5 really. All of them swing the 7 point games one way or the other, without influencing the 5 point or 9 point games. I really don't think professionals fine-tune their games to the komi that much, and certainly not to an extent that it would influence the amount of sekis.

[Bill Spight]

It's also not surprising that White's advantage with 7.5 komi under Chinese rules is more apparent in AlphaGo games than it is in human games, as AlphaGo is closer to perfect play.

I am not sure that we can draw any conclusion about komi from the published AlphaGo Master self play games, because nobody has said that they were randomly chosen from among the millions of such games. They may have been chosen because Fan Hui liked them, who knows?

[Bill Spight]

I really don't think professionals fine-tune their games to the komi that much, and certainly not to an extent that it would influence the amount of sekis.

I agree. I haven't seen any evidence that they do such fine tuning. Sure, Black and White played differently when there was no komi, but the difference of around 7 pts. was huge.

[John Fairbairn]

I haven't seen any evidence that they do such fine tuning

There are quite frequent references in the commentary literature to the "large komi" and the effect one's play. There was also the famous case of Kobayashi Koichi refusing to play with the Ing komi because he said it was too large. Currently we are seeing Ke Jie favouring White (as quite a few other players seem to do).

This may not be the same as fine tuning, but at least it shows awareness of a potential effect of komi size.

Even so, as you imply, it doesn't seem to be an issue among pros. If it becomes one, komi bidding may be an (awful) solution. There is also the possibility of resurrecting the old Meijin rule of using an integer komi and declaring jigos a win for White, with the proviso that in an event like a league, where ties can occur in the final placing, jigo wins count less than other wins. Another extreme would be to accept jigos and have a replay (as occurred last week with a quad ko).

[pookpooi]

I am not sure that we can draw any conclusion about komi from the published AlphaGo Master self play games, because nobody has said that they were randomly chosen from among the millions of such games. They may have been chosen because Fan Hui liked them, who knows?

"In my experience and the experiments we've run, komi 7.5 is very balanced, we only observe a slightly higher winrate for white (55%)."

Source from DeepMind's Julian Schrittwieser

https://www.reddit.com/r/MachineLearnin ... ittwieser/

[Bill Spight]

I haven't seen any evidence that they do such fine tuning

There are quite frequent references in the commentary literature to the "large komi" and the effect one's play.

But that does not mean that the changes in play have affected the results.

We saw this before with the 4.5 and 5.5 komis, decades ago. With the 4.5 komi the median result on the board was between 6 and 7 for Black, and with the 5.5 komi the median result was between 6 and 7. No fine tuning.

[jeromie]

I can understand the desire to eliminate ties in a tournament setting, but I wish more amateurs (and particularly online servers) use an integer Komi and allow a tie result. It seems to produce the most balanced game, and, unlike chess, go is unlikely to see a high number of results end in a tie. I think a tie game is an exciting outcome in a tense match.

[Bill Spight]

I am not sure that we can draw any conclusion about komi from the published AlphaGo Master self play games, because nobody has said that they were randomly chosen from among the millions of such games. They may have been chosen because Fan Hui liked them, who knows?

"In my experience and the experiments we've run, komi 7.5 is very balanced, we only observe a slightly higher winrate for white (55%)."

Source from DeepMind's Julian Schrittwieser

https://www.reddit.com/r/MachineLearnin ... ittwieser/

So they ran experiments and did not just rely upon the published games, which, IIUC, have an even higher win rate for White.

Anyway, calling 55% a slightly higher win rate suggests that Schrittwieser is not a go player. That's high enough, with human players, to suggest a komi of 5.5. I suppose, however, that in their experiments a 5.5 komi produced an even higher win rate for Black. Button go, anyone?