Komi Go / Discussion

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Dieter: It is my belief that komi is not fit for amateurs - say below 5 Dan. If you let me choose colors, I will always take White: 5.5 points in the pocket. We amateurs make so many mistakes that it really doesn't matter who begins. We are certainly not capable of maintaining the advantage of moving first. Professionals are so komi go fits them. The professional level is way above ours. If they decide 8 points is the proper komi I would strongly oppose its adoption in amateur games.

ChessWhiz: Yes, but on the other hand, just as (according to you) we can't maintain a first-move advantage, we can't keep a komi advantage either. I often win and lose games by 10 points or more, and a komi doesn't affect that. So if both players are the same strength, one should start and the other should receive komi. If the pros find that komi should be larger, by all means, make it larger! It simply offsets the advantage of the first move, and I think it's just as hard to retain a komi advantage as it is a first-move advantage. Of course, this is all in my humble opinion. What do the rest of you think?


SAS: Black is half a move ahead (on average) throughout the game; this advantage is there whether you are an amateur or a professional. But I think there is reason to suppose that komi should be smaller for weaker players. My reasoning is as follows. Suppose you and your opponent both drop an average of x points per move (compared to the perfect move). If Black and White both play the same number of moves, then this will cancel out (on average). But in fact Black often plays one move more than White, due to having the first move. If we assume that on average Black plays half a move more than White, then we must conclude that the komi required to make the game fair is x/2 less than the "correct" komi (which is probably 7). This adjustment is very small however - perhaps about 1 point for every 20 stones of strength. So I think a komi of 6 should be about right for most amateurs above 10 kyu. It would be good, however, to see some actual statistics for a few thousand amateur games of about shodan level, to see how things work out in practice.

The point that ChessWhiz makes about the komi not mattering so much in amateur games is correct. The higher x is, the higher its variance is likely to be, and this increases the probability that the winning margin will be large enough that the exact komi (within reason) will not matter.

Lezogzog: There is another point I'd like to make about going first. I like to take black because it allows me to a certain extend to choose my strategy, at least for the first moves. When I play a fuseki I'm more confident with, it makes me more confident for later moves. However, I do agree that it is better not to be too confident. Also, it is sometimes good to play strategies you are not used to, for obvious tutorial reasons. In conclusion, I would say that when I have the choice, I prefer to give komi when I play somebody about my strength (which is btw still low, but who knows).

Tim Brent: I feel for amateurs that 0.5 komi to prevent jigo is sufficient.

SAS: Sufficient for what? And what have you got against jigo?
Tim Brent: I actually have nothing against jigo, and have played one game so far at 0.0 komi. I assume most players want a result (i.e. Black win or White win). That is how I mean, sufficient to assure a result. Another reason for 0.5 to stop jigo is by analogy to Chess, where most games end up drawn, which can be frustrating.
SAS: If all you meant is that 0.5 komi is sufficient to prevent jigo, then you are of course correct (for professionals as well as amateurs). But 6.5 komi is also sufficient for that purpose, and is likely to make Black's winning percentage nearer to 50% (which is the main purpose of komi). Even between professionals, a komi of 7 would probably only cause about 3% of games to end in jigo, so the situation is not comparable to chess.

RobertJasiek: Komi for weaker players is a strategic preparation for playing stronger, so it should already use the stronger players' value. Whether some weaker players notice the strategic effects, depends on every player. E.g., I as a weaker player did notice the effect of even small komi changes and I altered my strategies accordingly.


Graham:

Theoretically
komi should be the value which makes the result a jigo with perfect play for black and white.
Pro games
with komi=5.5 have B winning ~55% and I believe analysis including the W+0.5 results suggests that komi=6.5 is about right. This is also consistent with the results of environmental go where pros value the first move at 13-14 points miai
Practically
far fewer kyu games are settled by komi type score differences, than dan games. This begs the question "Should komi be dependent on rank ?"
Personally
I prefer to take black and would do so up to komi=8. This is principally to have more control of fuseki and belief that komi=5.5 is too low especially for players of my strength (~1kyu). ie W will not have the skills to utilise komi.

Matt Noonan: I've heard this argument that the proper value of komi should make perfect play lead to jigo, but how reasonable is this? You could imagine (maybe for some other game) a proof that black has a strategy which makes him win by at least 25 points without actually giving such a strategy. But would we really start giving white 25 points of komi? I think komi should remain dynamic, the value fiddled with to keep white's winning percentages around 50%. It's kludgy, but it works and it is fair.


What are the suggested komi for non standard board sizes (7x, 9x, 11x, 13x, 15x, 17x, and 21x)? --Hu of KGS

See handicap for smaller board sizes. Charles Matthews


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