Nineteen point trick play
The extension at here is the famous nineteen point trick play. Typical continuations for this joseki would be
at a or b: see 3-4 point low approach one-space low pincer press.
If White falls into this trick play, White will get nineteen points in the corner, hence the name "nineteen point trick play".
White happily captures the corner, blissfully unaware that Black is intending to sacrifice the corner.
Tas: Is w3 the best? It seems to me that a would remove a black liberty to avoid black getting b in sente later, And white b would threaten to break the wall.
What happens after this (
on
)?
This seems even worse for white I think. Although the black wall is less perfect, white is running on the second line. Or am I missing something obvious?
shmolex: what happens if white instead connects on the first line with 2? It seems like black doesn't get the wall anymore.
Mef: If I'm reading correctly, instead of playing
, black will go for the net immediately, white can only escape by giving black the corner.
shmolex: ah, I see it now. Thanks.
The sequence up to results in a huge success for Black. White has 19 points in the corner, but Black has such a thick wall outside that its value is much bigger than White's corner. Besides, Black a is sente. (The Iron Wall page shows a continuation of this example.)
White can play at to break this trick play. Black must defend at
and
attacks
. The result is favourable for White. The three white stones around
form a big bulge.
tderz the yose seems different. Black got now more than in above variant
See also topic:1097 for more discussion on this trick play, as well as a tewari analysis of it. Another tewari analysis of this trick play can be found at Tewari Example 8.