[computer-go] cgos

[Nick Wedd]

In message <2C9222B095ED48A59F377BAE9663058B at harriPC>, Harri Salakoski 
<harri.salakoski at elisanet.fi> writes
>Hi is last black move A4 really illegal in cgos rules?
>Just ensure before start change things. It seemed weird.
>White D9 shouls change board situation and white kills two stones 
>before A4 is getting then
>one stone back fine? t. harri
>
>W A4
>9 WW..W.WWW
>8 ...W.W.W.
>7 WBW.WWWW.
>6 WBBWBBWWW
>5 .WWWBBBBB
>4 BWBBBBBBB
>3 .BBB.B.B.
>2 B.BBBBB.B
>1 BBBBBBBB.
> ABCDEFGHJ
>
>W D9
>9 WW.WW.WWW
>8 ...W.W.W.
>7 WBW.WWWW.
>6 WBBWBBWWW
>5 .WWWBBBBB
>4 BWBBBBBBB
>3 .BBB.B.B.
>2 B.BBBBB.B
>1 BBBBBBBB.
> ABCDEFGHJ
>
>B A5
>9 WW.WW.WWW
>8 ...W.W.W.
>7 WBW.WWWW.
>6 WBBWBBWWW
>5 BWWWBBBBB
>4 BWBBBBBBB
>3 .BBB.B.B.
>2 B.BBBBB.B
>1 BBBBBBBB.
> ABCDEFGHJ
>
>W A3
>9 WW.WW.WWW
>8 ...W.W.W.
>7 WBW.WWWW.
>6 WBBWBBWWW
>5 .WWWBBBBB
>4 .WBBBBBBB
>3 WBBB.B.B.
>2 B.BBBBB.B
>1 BBBBBBBB.
> ABCDEFGHJ
>
>B A4
>9 WW.WW.WWW
>8 ...W.W.W.
>7 WBW.WWWW.
>6 WBBWBBWWW
>5 .WWWBBBBB
>4 BWBBBBBBB
>3 .BBB.B.B.
>2 B.BBBBB.B
>1 BBBBBBBB.
> ABCDEFGHJ

Here are the positions, edited to make them more legible:

W A4  [in fact it is B who has just played A4]

  O O . . O . O O O
  . . . O . O . O .
  O # O . O O O O .
  O # # O # # O O O
  . O O O # # # # #
  # O # # # # # # #
  . # # # . # . # .
  # . # # # # # . #
  # # # # # # # # .


W  D9  [Note this position, I will refer to it later]

  O O . O O . O O O
  . . . O . O . O .
  O # O . O O O O .
  O # # O # # O O O
  . O O O # # # # #
  # O # # # # # # #
  . # # # . # . # .
  # . # # # # # . #
  # # # # # # # # .


B  A5

  O O . O O . O O O
  . . . O . O . O .
  O # O . O O O O .
  O # # O # # O O O
  # O O O # # # # #
  # O # # # # # # #
  . # # # . # . # .
  # . # # # # # . #
  # # # # # # # # .


W  A3

  O O . O O . O O O
  . . . O . O . O .
  O # O . O O O O .
  O # # O # # O O O
  . O O O # # # # #
  . O # # # # # # #
  O # # # . # . # .
  # . # # # # # . #
  # # # # # # # # .


  B A4

  O O . O O . O O O
  . . . O . O . O .
  O # O . O O O O .
  O # # O # # O O O
  . O O O # # # # #
  # O # # # # # # #
  . # # # . # . # .
  # . # # # # # . #
  # # # # # # # # .


If "positional superko" is in force, this last move is illegal, as it 
recreates the position noted previously.

Nick
-- 
Nick Wedd    nick at maproom.co.uk