Nineteen point trick play

    Keywords: Joseki
[Diagram]
Nineteen point trick play  

The extension at B5 here is the famous nineteen point trick play (also known as the "eighteen and a half point trick play"). Typical continuations for this joseki would be B5 at a or b: see 3-4 point low approach one-space low pincer press.

If White falls into this trick play, Black will give up nineteen points in the corner (hence the name "nineteen point trick play") but get a huge advantage anyway. Read on!

[Diagram]
Nineteen point trick play  

W3 and W5: she is taken in by this trick play.

[Diagram]
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.

[Diagram]
Nineteen point trick play  

unkx80: Seems to me that it is business as usual for Black...

[Diagram]
Nineteen point trick play (W3 at black+circle)  
[Diagram]
Nineteen point trick play (W3 at black+circle)  

Tas: With this 5 black won't get both 8 and a in sente.

Herman: With this 5, black will play 6 at b and capture the white stones along the top edge.

What happens after this W9 (W7 on B2)?

[Diagram]
Nineteen point trick play  

Possibly this?

[Diagram]
Nineteen point trick play  

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?



[Diagram]
Nineteen point trick play  

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 B3, black will go for the net immediately, white can only escape by giving black the corner.

shmolex: ah, I see it now. Thanks.


[Diagram]
Nineteen point trick play (W3 at marked stone)  

The sequence up to W9 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.)

[Diagram]
Nineteen point trick play counterplay  

White can play at W3 to break this trick play. Black must defend at B4 and W5 attacks black+circle. The result is favourable for White. The three white stones around black+circle form a big bulge.

[Diagram]
Nineteen point trick play counterplay  

Alternatively, White can choose to play at W1 and W3 in this diagram. The effect is similar.

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.


Nineteen point trick play last edited by 90.184.6.41 on January 18, 2017 - 22:17
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