This game is GoGoD 1600-00-00n, between Honinbo Sansa (W) and Rigen. OC, today's pros are stronger, in no small part because we have learned from their mistakes.
- Click Here To Show Diagram Code
[go]$$Bcm37 Textbook shape
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . W . . 1 . . X . . . . O X . . . |
$$ | . . . , . . . . . , . . . O X X X . . |
$$ | . . a 2 . . . . . . . . . 4 O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . 3 W . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . X . O . . . . . . . . . . . . |
$$ | . . O . . X O . . . . . . . . . X . . |
$$ | . . X . X O . . . . . . . . . . . . . |
$$ | . . X , X O . . . , . . . . . , O . . |
$$ | . . X O O . . O . X . . X . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
These were the days before
corners, sides, center, which explains why Sansa had not enclosed the top left corner earlier. But
![black 37 :b37:](./images/smilies/b37.gif)
not only made a base, it threatened to invade White's thin corner position at
a. So White protected it with
![white 38 :w38:](./images/smilies/w38.gif)
which, with the
![white with circle :wc:](./images/smilies/wc.gif)
stones made what would later be a textbook shape in the corner. (
![white 38 :w38:](./images/smilies/w38.gif)
might also have been at
a.)
![black 39 :b39:](./images/smilies/b39.gif)
intruded into the corner, a mistake that lost 17½% to par by Elf's reckoning. Then White made the solid connection,
![white 40 :w40:](./images/smilies/w40.gif)
.
- Click Here To Show Diagram Code
[go]$$Bcm39 Variation for ![black 39 :b39:](./images/smilies/b39.gif)
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 6 . . . O . . . . |
$$ | . . . O . . X . . X . . . . O X . . . |
$$ | . . . , . . . . . , . . 2 O X X X . . |
$$ | . . . O . . . . . . . . 4 1 W 5 . . . |
$$ | . . . . . . . . . . . . . . 3 . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . X . O . . . . . . . . . . . . |
$$ | . . O . . X O . . . . . . . . . X . . |
$$ | . . X . X O . . . . . . . . . . . . . |
$$ | . . X , X O . . . , . . . . . , O . . |
$$ | . . X O O . . O . X . . X . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
![black 39 :b39:](./images/smilies/b39.gif)
cuts White in two in the top right, then captures the
![white with circle :wc:](./images/smilies/wc.gif)
stone.
![white 44 :w44:](./images/smilies/w44.gif)
supports his group and threatens the Black base. The White stones in the upper right side have been weakened.
- Click Here To Show Diagram Code
[go]$$Wcm38 Key point
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O 2 . . . |
$$ | . . . O . . X . . X . c . . O X . . . |
$$ | . . . , . . . . . , . . . O X X X . . |
$$ | . . a b . . . . . . . . . 1 O . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . X 3 O . . . . . . . . . . . . |
$$ | . . O . 4 X O . . . . . . . . . X . . |
$$ | . . X . X O . . . . . . . . . . . . . |
$$ | . . X , X O . . . , . . . . . , O . . |
$$ | . . X O O . . O . X . . X . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The solid connection,
![white 38 :w38:](./images/smilies/w38.gif)
, is the key point for White. It radiates strength towards the right side, the top side, and the center, and weakens Black's corner. After
![black 39 :b39:](./images/smilies/b39.gif)
White takes sente in the bottom left quadrant, but
a,
b, or
c would also be good.