# Counting a surrounded non-alive carpenter's square

I was playing against Crazy Stone and we ended up with (essentially) this corner situation:

``````\$\$W
\$\$ -------------
\$\$ | . . 5 X O .
\$\$ | 4 1 3 X O .
\$\$ | . 2 , X O .
\$\$ | X X X X O .
\$\$ | O O O O O .
\$\$ | . . . . . .
``````

This certainly taught me (black) a valuable lesson about what I learned is called the "Carpenter's Square" and how I should not let W1 happen.

What I did not understand was the counting of this situation. I would have expected this to be counted under seki rules (as far as I can tell, Crazy Stone uses Japanese scoring), which in my understanding means all stones are alive and the four empty intersections are dame, so this corner is worth zero for either player.

The program however marked the black stones as dead and counted the corner as white territory, making the above diagram worth 22 points for white.

Is my understanding incorrect? Or the computer's? How should this situation be counted?

• I do not know about Crazy Stone, but many programmes mark what they think is alive or dead but let you click on groups to change their status. Commented Apr 26, 2020 at 21:15

During the game

``````\$\$
\$\$ -------------
\$\$ | a b O X O .
\$\$ | X O O X O .
\$\$ | . X , X O .
\$\$ | X X X X O .
\$\$ | O O O O O .
\$\$ | . . . . . .
``````

The corner is not settled yet, as both players can choose to:

• either start a ten thousand year ko, white by playing at a and black by playing at b
• or settle for a seki, if black plays at a or white plays at b.

At scoring time

If no move has been added in the corner, I would expect this to be considered a seki under Japanese rules (see example 12).

Under Chinese rules, both players would have to agree on the seki, or keep playing (in which case a or b will eventually be played).

• Thanks, interesting. But the page you link to says "In fact, the game can end with the position remaining unplayed, in which case it is considered a seki."
– balpha
Commented Mar 28, 2016 at 16:19
• @balpha I tried to clarify my answer. Commented Mar 28, 2016 at 18:06
• Ah, I see. So indeed the corner shouldn't have counted for anything. Thank you!
– balpha
Commented Mar 29, 2016 at 12:26
• Also, I believe that if it is concluded a seki then Black gets one point of territory. Commented Apr 4, 2016 at 20:54
• @TylerDurden the Japanese rule doesn't grant points in a seki, other rules do. See "Can you count points in a seki?" britgo.org/rules/compare.html Commented Apr 4, 2016 at 21:22