(Beginner) Counting question

[Baywa]

The game recording says W+16.5 for this game from the preliminary round of the 22nd Samsung Cup. With the komi of 6.5 points that means W+10 on the board. Now, my sgf-client and my counting by hand says W+9 on the board. Where's the error? Does Black have to cover once more in his own territory?

P.S. I added the last counting "frame" to the kifu. After removing the dead stones from the board, White has 25 and Black has 19 prisoners.

[Pio2001]

Strange indeed.

Maybe the komi was in fact 7.5.

[Vesa]

Could be a simple error in counting. The difference is so big that one lost prisoner doesn't matter.

Cheers,
Vesa

[oren]

Also the recorder enters it manually and this is international. It's possible someone just mistyped and once it was in the system, it was done. The score isn't really important. Usually they get the winner right.

[John Fairbairn]

This is a known problem. I think the answer may be that the game came originally from a Chinese source. There White wins by 4.5 zi on the board, to which you add 3.75 zi komi, giving 8.25. The rule of thumb is to double that to get the Japanese score (e.g. as presented in Kin's pages). But the rule of thumb is dumb (new proverb!).

[Pio2001]

So, basically, you are saying that the game was typed by someone who is chinese and thought that the komi was 7.5, like in China ?

[Baywa]

Thanks! I thought there was something subtle that I missed! Since the margin was so large, I guess nobody really cared about one point more or less.

[EdLee]

Since the margin was so large, I guess nobody really cared about one point more or less.

Hi Baywa, it's not the margin but the principle that matters.
Pros (and AlphaGo!) are fighting for fractions of a point!

[Calvin Clark]

I noticed this game, too. Sometimes the reported score will not match your own count. A common class is games played with Ing Rules, where time penalty may be in effect and players sometime pay in points for extra time periods. If this is not noted in the game the recorded score might be very far from what the board shows. I was scratching my head recently on of those until I realized I was looking at game from the Chang-ki Cup, and then it hit me: oh, that Chang-ki.