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Could someone help me with a very basic corner problem?
http://www.lifein19x19.com/viewtopic.php?f=4&t=6906		 Page 1 of 1
Author:  koticgood [ Sat Oct 06, 2012 2:58 am ]
Post subject:  Could someone help me with a very basic corner problem?
Move 97 in the .sgf



I really messed it up in the game, but my opponent let me off the hook. Throw-in at a4 would have put me in trouble. Just wondering what the most efficient way to deal with the situation is. I messed around with several variations that worked, but I don't know the best way to play it. I should really do some tsumego, as this seems like a classic/basic situation. :study:

Attachments:
cornertsumego.sgf [4.73 KiB]
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Author:  EdLee [ Sat Oct 06, 2012 3:25 am ]
Post subject: 
Locally, W seems dead shape; a first feeling is the first-line hane A5 for :black: 104 --
which was missing from your vars (the other hane C1 was also missing :)) --
but, you have a cut at D6, so, complications... :study:
(Without the weakness at D6, I'm pretty sure the A5 hane kills.)
Author:  Cassandra [ Sat Oct 06, 2012 3:37 am ]
Post subject:  Re: Could someone help me with a very basic corner problem?
Black C4, White B4, Black B2, and there is no way, White's group can get more than three liberties.

Black's group above has four liberties, so White cannot win the Semeai, even if she cuts (i.e. something like reducing Black's upper group to three liberties).
Author:  koticgood [ Sat Oct 06, 2012 3:47 am ]
Post subject:  Re: Could someone help me with a very basic corner problem?
Cassandra wrote:
Black C4, White B4, Black B2, and there is no way, White's group can get more than three liberties.

Black's group above has four liberties, so White cannot win the Semeai, even if she cuts (i.e. something like reducing Black's upper group to three liberties).


That was one of my variations, but instead of W b4, I have W b6. It might be gote, but the b4 follow up is actually annoying. I thought B should have a better play in this situation (c5 is similar to c4).
Author:  Cassandra [ Sat Oct 06, 2012 3:54 am ]
Post subject:  Re: Could someone help me with a very basic corner problem?
koticgood wrote:
Cassandra wrote:
Black C4, White B4, Black B2, and there is no way, White's group can get more than three liberties.

Black's group above has four liberties, so White cannot win the Semeai, even if she cuts (i.e. something like reducing Black's upper group to three liberties).


That was one of my variations, but instead of W b4, I have W b6. It might be gote, but the b4 follow up is actually annoying. I thought B should have a better play in this situation (c5 is similar to c4).

You played Black A3, instead of my suggested B2.

A move at B6 is not possible, because this point is occupied already.

Starting point of my comment is your variation tree after W 103.
Author:  EdLee [ Sat Oct 06, 2012 3:57 am ]
Post subject: 
koticgood wrote:
Cassandra wrote:
Black C4, White B4, Black B2...
That was one of my variations, but instead of W b4, I have W b6.
Not sure which var in your SGF you're referring to --
after Cassadra's C4 for :black: 104, W cannot play B6 since there is already a stone at B6 ( :b100:).
Author:  koticgood [ Sat Oct 06, 2012 4:30 am ]
Post subject:  Re: Could someone help me with a very basic corner problem?
Cassandra wrote:
koticgood wrote:
Cassandra wrote:
Black C4, White B4, Black B2, and there is no way, White's group can get more than three liberties.

Black's group above has four liberties, so White cannot win the Semeai, even if she cuts (i.e. something like reducing Black's upper group to three liberties).


That was one of my variations, but instead of W b4, I have W b6. It might be gote, but the b4 follow up is actually annoying. I thought B should have a better play in this situation (c5 is similar to c4).

You played Black A3, instead of my suggested B2.

A move at B6 is not possible, because this point is occupied already.

Starting point of my comment is your variation tree after W 103.


Ah, I had the starting point incorrect, sorry. Your sequence definitely seems the cleanest.
Author:  Bill Spight [ Sat Oct 06, 2012 5:12 am ]
Post subject:  Re: Could someone help me with a very basic corner problem?
I would not call this very basic. (See recent thread. ;))

A few variations. (And what is with :b16: and :b26: ?)



Edit: Added variation for W-107.
Author:  koticgood [ Sat Oct 06, 2012 5:27 am ]
Post subject:  Re: Could someone help me with a very basic corner problem?
Bill Spight wrote:
I would not call this very basic. (See recent thread. ;))

A few variations. (And what is with :b16: and :b26: ?)



Thanks. Move 16 I had no idea where to play, so I just played that shape randomly :oops: . Your move obviously looks much, much better, thanks for showing me. As for move 26, I realized right after I played it that it was a thank-you move, I just did it out of instinctively adding a space to my jump after I nobi (for whatever reason, lol).
Author:  Bill Spight [ Sat Oct 06, 2012 5:38 am ]
Post subject:  Re: Could someone help me with a very basic corner problem?
Added variation to previous post. :)
Author:  EdLee [ Sat Oct 06, 2012 5:32 pm ]
Post subject: 
Thanks, Cassandra, Bill: :)
I got confused with the following shape --
the first-line hane (a) works both here and in koticgood's shape,
but Cassandra's push-and-clamp is better in koticgood's case
because it kills W faster, and so B doesn't have to worry about the cut at (b).
The :w3:- :b4: - :b6: exchange changes everything. :)
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