Big Sacrifice To Get A Wall
There is a rather standard sacrifice that comes up in several situations, which allows someone to build an impressive wall. The basic shape is this one:
White sets up a semeai with the geta . The marked white stones are the sacrifice, they do not have enough liberties to the left to win the semeai.
There is either already a white stone at a, or white can add it in sente, so that black cannot break out of the geta
The end result will give white an impressive wall.
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Trick plays in joseki
Nineteen point trick play
One of the most famous examples is the 19 point trick play:
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4-4 ogeima enclosure
This same sacrifice pattern is found in this standard 4-4 enclosure
Note that KataGo rates
White wins the semeai in the corner, but Black’s sacrifice has given him an impressive wall, worth much more than the corner points. Note: At |
3-4 high approach, keima joseki
The pattern occurs often with invasions of large knight move extensions:
Another standard joseki situation. Again, the presence of the marked black stone makes the invasion Again, KataGo points to errors by both sides: |
3-4 high approach, one point jump joseki
Another joseki variant, similar to the one above. Because of the low position of the marked stone, black cannot squeeze by cutting at As always, |
Example from professional play
This is Otani Motohiro (white) versus Kuwahara Munehisa in 1942. In this example, the sacrifice works even with best play by both sides.