Stretch as good shape

The stretch to come out  

In this position, the cautious stretch (or, better, stand) of White 1 is the standard way for White to come out into the centre.

Dangerous shape  

White 1 here is a shape involving a dangerous chance for Black to cut, combining plays at a and b.

Continuation  

Black has the opportunity to force White with 2, and then employ the wedge 6 to cut, appying the tesuji 8. Now White needs to live immediately at a, so that the white ponnuki will come under attack.

Assuming Black is strong in the centre, which is quite likely in positions leading to the initial formation, this is dangerous for White. Black also has an option of playing 6 and 8 in the other order; or playing bluntly to cut starting at b. Holding back one line makes good sense.

Wedge joseki  

These are standard plays when the marked white stone is a wedge on Black's nirensei or orthodox fuseki side, and Black's marked stone a checking extension. Black 6 resists when White 5 slides. When later Black returns to play at a, White has a problem with shape exactly as before. White can correct it by playing the butt b; possibly too crude and aji keshi, though. For a game example of the cut occurring in this shape, see Ch'oe Myeong-hun-Zhou Junxun 2001-07-07 in the Fujitsu Cup.

Charles Matthews