I am playing with SmartGo and I don’t understand one situation.

I am playing as Black.

$$ +---------+
$$ |O.O.OX.X.|
$$ |.OXXOXXO.|
$$ |2XO.OOOX.|
$$ |1XXO.XyXO|
$$ +---------+

Why am I allowed to play at G1 (marked y), but not at A2 (n)? I am surrounded by my own stones in both cases.

  • 1
    It is not what you were asking about, but note that both G1 and A2 (if your rules allow suicide) lose you points: it is normally only good to play inside your territory if it saves some of your stones from capture, usually by connecting them to the rest or my making (two eyes)[senseis.xmp.net/?TwoEyes]. Otherwise you are passing up on a chance to expand your area, and may even help your opponent capture your stones.
    – PJTraill
    Commented May 2, 2020 at 21:11
  • I am glad if it helps – I have just noticed I got the markup for a link wrong, but it seems clear enough anyway.
    – PJTraill
    Commented May 2, 2020 at 21:30
  • yes, I already knew that page. There is a tremendous amount of info on the sensei's library site!
    – Thomas
    Commented May 2, 2020 at 21:31
  • It's not the stone that you play that matters, but the resulting string of solidly connected stones. Commented May 11, 2020 at 20:23
  • In other words: for the same reason that, for example, the already present Black stone at g6 doesn't get removed from the board (or at b3, etc.). Commented Dec 28, 2023 at 3:36

1 Answer 1


Playing in the space above 82 would result in that black group having no liberties while the white groups surrounding it do still have liberties, so the group would immediately be captured by white. According to Wikipedia, most rulesets prohibit moves like that. If you play in the bottom right hole, on the other hand, that black group still has multiple liberties.

  • I read the whole section on Wikipedia, it makes sense now. Thanks!
    – Thomas
    Commented Apr 30, 2020 at 20:42

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