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Defending two-space extensions
http://www.lifein19x19.com/viewtopic.php?f=11&t=10159		 Page 1 of 1
Author:  joellercoaster [ Tue Apr 15, 2014 1:18 am ]
Post subject:  Defending two-space extensions
I am getting a good thumping in a correspondence game. This is not in itself unusual, but I'm starting to notice some common things that go wrong in my games... one of them is that the oft-repeated advice of making a base with two-space extensions on the third line seems good, but I then fail to defend them when people inevitably put them under pressure.



:b29: - so far, so good.
:w30: - seems like a reasonable response.
:b31: - was this where it all started to go wrong? Should I have accepted the split as inevitable at this point and extended into the middle (or extended my base somewhere like O2)?

By :w38: I am already floundering, and by :w46: I am starting to suspect the group is dead.

(Also, not related to the main topic, but 1. am I right in feeling that :b67: was a terrible idea, leading to the opportunity of the rest of the left-side disaster than then ensues? and 2. :w72: seems like the kind of thing that would be a common pattern of attack - if I cut on the other side, towards the 'start' of the keima, I end up losing a stone straight away... but maybe I just need to wear it?)

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Author:  EdLee [ Tue Apr 15, 2014 1:28 am ]
Post subject: 
joellercoaster wrote:
but I then fail to defend them when people inevitably put them under pressure.
Yes, :b33: is like somebody is coming with an ax to chop off your hand, and you decide to grab $100 from his wallet.
Sure, you got some of his cash. Good trade for you ? :)
Author:  Uberdude [ Tue Apr 15, 2014 3:26 pm ]
Post subject:  Re: Defending two-space extensions
joellercoaster wrote:
...making a base with two-space extensions on the third line seems good, but I then fail to defend them when people inevitably put them under pressure.


A two space extension with checking extensions (opponent's stone one space jump away) on both sides is cramped and vulnerable. You usually want to have sente to reinforce it with a jump. But taking a step back, the important word here is "defend". If you are defending a weak group it's likely your opponent is attacking and making profit so you had better have got something for yourself in exchange, e.g. a big tenuki earlier. So you've got to think about do you want to get into the sort of situation where you are defending a two space extension. In your game the answer is no.

joellercoaster wrote:
:b29: - so far, so good.


Well..... I made some comments about the earlier game. Some are quite a bit beyond your level but you and others may find them interesting. But the important move was 19 at r6. This wrong direction set up all your troubles with the two space extension. m3 too, though that move seems reasonable and just leads to a fight, but see my variation for what looks like a simple and good alternative.

joellercoaster wrote:
:w30: - seems like a reasonable response.
:b31: - was this where it all started to go wrong? Should I have accepted the split as inevitable at this point and extended into the middle (or extended my base somewhere like O2)?


See the comments, things started to go wrong with :b19: :)

joellercoaster wrote:
By :w38: I am already floundering, and by :w46: I am starting to suspect the group is dead.

Hallelujah! Your opponent gave you a wonderful way to sacrifice your now junk group. Death is a blessing. End the suffering. :D



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Author:  Bill Spight [ Tue Apr 15, 2014 3:39 pm ]
Post subject:  Re: Defending two-space extensions
Uberdude wrote:
joellercoaster wrote:
By :w38: I am already floundering, and by :w46: I am starting to suspect the group is dead.

Hallelujah! Your opponent gave you a wonderful way to sacrifice your now junk group. Death is a blessing. End the suffering. :D


Words of wisdom. Look for opportunities to sacrfice. :)
Author:  joellercoaster [ Wed Apr 16, 2014 2:46 am ]
Post subject:  Re: Defending two-space extensions
Thank you both! This is extremely interesting and immediately helpful. Even the bits that are over my head plant seeds about the (for now) unseen world of tactical Go.

(The obvious one-liner is "in order to defend a two-space extension, maybe actually try to defend it" but there's so much stuff here to work with, I'm going to unpack it more carefully on a physical board this evening. Thanks again.)
Author:  Xiaoding [ Thu May 29, 2014 7:03 pm ]
Post subject:  Re: Defending two-space extensions
I think the principle here is, when one of your stones is attached to, you must answer.

The attachment can be direct on the side, or the diagonal, as in your case. You must answer right there. Especially when there are a bunch of enemy stones around, then your #1 priority should be making life, or connecting.
Author:  EdLee [ Fri May 30, 2014 12:19 am ]
Post subject: 
Xiaoding wrote:
I think the principle here is, when one of your stones is attached to, you must answer.
Nothing is farther from the truth.

We strive to play the best move. If it means we must reply to the attach move, then so be it.
And if it means we must not reply, then it's perfectly OK, too.

Principles can be traps. And they often are, for many beginners.
Sometimes, a guideline works; other times, it fails.
The difficult thing is to decide for a particular situation, what is the best move or sequence.
Author:  hyperpape [ Fri May 30, 2014 6:10 am ]
Post subject:  Re: Defending two-space extensions
Yes, to go partial Jasiek on this*, the principle would be something like

When your stone is attached to or shoulder hit, you must
1) Respond locally.
2) Accept the sacrifice of the stones.
3) Play a sente move elsewhere, before returning to this decision point.

* Read: try to be more formal than is really appropriate.
Author:  leichtloeslich [ Fri May 30, 2014 6:47 am ]
Post subject:  Re: Defending two-space extensions
hyperpage wrote:
Yes, to go partial Jasiek on this*, the principle would be something like

I think you just went full Jasiek.

Anyway, your 2nd principle doesn't make too much sense. Not every attachment or shoulder hit instantly kills.

I would have corrected Xiaoding somewhere along the lines of
"An attachment is a severe move that, if ignored, will likely result in a local loss."

Since "winning" a particular local situation isn't the goal of the game, quite clearly we are free to ignore attachments if we have better things to do elsewhere.
Author:  oren [ Fri May 30, 2014 10:12 am ]
Post subject:  Re: Defending two-space extensions
"Play the best move on the board. It may or may not be local." :)
Author:  Bill Spight [ Sat May 31, 2014 9:29 pm ]
Post subject:  Re: Defending two-space extensions
A few comments. :)



Edit: Added some plays and comments. :)
Author:  skydyr [ Sun Jun 01, 2014 5:51 pm ]
Post subject:  Re: Defending two-space extensions
oren wrote:
"Play the best move on the board. It may or may not be local." :)


I know I'd much rather play the killing move on the board to my left than deal with the mess on my own.
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