Net example 7

Path: <= Net =>
  Difficulty: Advanced   Keywords: Tactics

jvt I have seen a series of net problems like the one below on a Japanese web site :

[Diagram]
Black to play  
[Diagram]
Black 5 is a net  

Even though it does not prevent White from increasing its number of liberties, B5 prevents White from escaping.

[Diagram]
Continuation  

W10 at B1. Then White is caught in a ladder (Black 11 at a).

[Diagram]
Another continuation  

Alex Weldon: Probably worth showing for beginners what happens if White tries to atari her way out. If W1, expecting Black to connect at W3 so that she can then escape by playing at B4, Black squeezes with B2 and B4. White connects with W5 at the marked point and Black catches her in a ladder with B6, B8 and B10. As a question to stronger players: Is there still a way for Black to capture if this ladder is also no good for Black (some ladder breaker stone that we can't see here)? I don't see it.

[Diagram]
Stopping the Ladder  

Dan Halver: I'm not at all a "stronger player" but this seems to be a way to stop the ladder. Though I believe white could evade capture by playing a, forcing black to play b, then white can capture the designated stones by playing c (Since I have just seven hours ago started learning GO, please correct any mistakes I have made) : )

[Diagram]
Stopping the Ladder  

LukeNine45: Well, that's an interesting move... Sadly, B2 doesn't work out so well, as white will capture by playing atari at W3 (black can't escape). Basically, after W1, if the ladder doesn't work for black, black's only options to save his stones are to play at W3 or a, and black is still in big trouble. If the ladder didn't work, black really needed to not start Alex's variation at all, because this is a disaster...

[Diagram]
If push comes to shove...  

Mef: If the ladder is bad for black, I think he can set up a ko with B4. If white declines to fight the ko, black has a chance to set up a different ladder, which may or may not work depending on where exactly the original ladder breaker is.

(sIG): But suppose an extra white stone is in L 11 (that is, it breaks both ladders), doesn't that make it useless for black to pursue white in the first place? Won't white gain advantage? Does this mean there's a fault in the exercise or do we simply suppose the rest of the board empty?

[Diagram]
Black 5 is a net  

Imagist: What about this?

[Diagram]
Black 5 is a broken net  

MrTenuki: Unfortunately, the sequence above doesn't work. Black has weaknesses at a, b, and c. Even if black covers both a and b by playing at b, white can still capture B2 and the marked stones. If black defends at d, white simply breaks out or captures the four stones by playing at b.

idigo: Yeah, but B2 is a mistake by black. B2 should be at W3.

[Diagram]
Correct sequence  

Path: <= Net =>
Net example 7 last edited by axd on October 28, 2007 - 16:41
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