Cosumi claims that I won this game by 37 points:

Go board with even territory between the two sides

[9×9, Level 0] Black(You) Wins by 37 Points - Go Browser Game COSUMI

But it looks even to me.

Am I missing something, or does the site sometimes get the score completely wrong?


Strange. The next morning, the same URL shows the upper-right corner as captured:

enter image description here

That might account for the score but, as far as I can tell, White still owns that territory.

Something strange is going on here. (Does Cosumi have a bug-reporting mechanism?)

  • 3
    The score is wrong, both white groups are alive Sep 7 '20 at 9:23

You are right that the top right belongs to White with correct play, but according to the programme Sabaki White wins by one point (because they have a captive). It is conceivable, but somewhat unlikely, that White could make enough errors for Black to win.

The score

Sabaki calculates the score like this for area scoring:

enter image description here

and like this with territory scoring:

enter image description here

The top right

To be on the safe side, I plugged your SGF into KataGo (via Sabaki), and it showed me a ko in the top right that Black cannot win: not only do they have hardly any threats, even if they did, they could not finish the ko in their favour.

The sequence that KataGo found was this:

$$Bcm1 Trying for a ko
$$ +---------+
$$ |..XOO.a25|
$$ |.X.XO.O1c|
$$ |..,XXO4d3|
$$ |..XOXOXXO|
$$ |OOOOOX.X.|
$$ |....OX.X.|
$$ |.O..OOX..|
$$ +---------+

Unfortunately for Black, White simply has to connect with ➅ at a and Black has no way of finishing the ko to kill White. White can just wait for Black to run out of threats and then capture at c and d.

Black’s only chance is if White plays the ko wrongly, for example:

$$Wcm6 White messes up (9 retakes, 13 @ 7)
$$ +---------+
$$ |..XOO36OX|
$$ |.X.XO2OX1|
$$ |0.,XXOO.X|
$$ |57XOXOXXO|
$$ |OOOOOXxX.|
$$ |....OX.X.|
$$ |.O..OOX..|
$$ +---------+
  • capturing ➅ instead of connecting at ⓫,
  • threatening with ➉ instead of the deadlier threat at x,
  • missing x again after Black takes at ⓫ and therefore giving up the ko, so
  • Black wins by 27 (area) or 26 (territory).

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