Komi and perfect play

I’m wondering… why have half-point komi values? The obvious answer is that it makes ties impossible, and yet… if the point of komi is to compensate for black’s advantage in moving first, then it seems like the correct komi value combined with mathematically perfect play on both sides should in fact result in a tie.

So the followup question is who does the current standard komi value favor? Again with mathematically perfect play on both sides does 6.5 give white the game?


AFAIK super-human AIs consider, that 6.5 favors black, while 7.5 favors white.


This post is a bit old (May 2020), but it addresses KataGo “opinions” of fair values of komi:


In my opinion even 0.5 komi favors white. Maybe too many games played and then who is better decided is a solution.

Tie sounds a little bit awkward to me. We are biologic entities so that we will make mistakes eventually but in the and weaker will make more mistakes and stronger will win in long time.

Time is important.

I see you are asking about perfect play and mathematically, on the 9x9 5.5 komi gives too many Half Point Wins in my experience. So the komi doesn’t look so bad. But when you think about 19x19 there are too many spots that will be pllayed mistakely that even komi will be forgotten.

In the end if you become a 9p strong please enlighten us because I find it so weird they are not talking about anything. I can’t find it anywhere. Not cool.

See you around by the way.

The thing I meant to ask about that a few times upon reading it is “what’s the definition of fair?”

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Well by fair they are meant to say no one is superior to the other in the beginning.

I tried to point out human is biologic and under stress.

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Sure, human players are always going to introduce variables – but I think it’s fair to consider theoretically perfect play (even if no person will ever be able to execute it) when trying to determine what it most fair in rules. That way the stage is fair, and it’s now up to you how well you can capitalize on that, or not.


The sad, honest truth seems to be that most go players don’t like the idea of ties, however rare they would be. :frowning:


I am deeply impressed that the komi considered “fair” by Katago (something as 6,5 it seems) is indeed the komi already practiced by humans before modern AI. I really respect professionals for finding out the balance of 1 point in an empty board.


I’m not so sure it’s this exactly. More that professional game organisers don’t like ties and the professional game is where the rules are made and most go players then follow those rules.


That’s right. In fact, Go Professionals love the ideas of ties. When Japanese Newspapers started sponsoring tournaments they used komi and still discovered how much Go Players love ties.

Turns out that Go Players love game fees and were willing to “accept” a tie to play again for another fee.


Ties don’t seem to hurt the chess world much; how many high level tournament matches are settled with 2 wins, 1 loss, and a bunch of draws… or even just 1 win and a whole bunch of draws?