defending the corner

For lessons, as well as threads about specific moves, and anything else worth studying.
Post Reply
nickxyzt
Beginner
Posts: 16
Joined: Mon Jan 03, 2011 1:48 am
Rank: 4 kyu
GD Posts: 30
Been thanked: 2 times

defending the corner

Post by nickxyzt »

Hi,

I have a question regarding the following diagram (Get strong at tesuji, problem #14) - black to defend the corner:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O . . . . . . . . . . . . . . . |
$$ | . . X O . X . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The answer in the book is:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O . . . . . . . . . . . . . . . |
$$ | . 2 X O . X . . . . . . . . . . . . . |
$$ | . 1 3 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Could anybody point out what is the difference with the next diagram? What am doing wrong?
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O . . . . . . . . . . . . . . . |
$$ | . 2 X O . X . . . . . . . . . . . . . |
$$ | . 3 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Top
lovelove
Lives in gote
Posts: 604
Joined: Mon Nov 05, 2012 4:21 am
Rank: Tygem 5 Dan
GD Posts: 0
Location: Séoul, Corée
Has thanked: 88 times
Been thanked: 365 times

Re: defending the corner

Post by lovelove »

Your diagrams are exactly the same result, but there can be difference when white tenukis.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 1 O O . . . . . . . . . . . . . . . |
$$ | . . X O . X . . . . . . . . . . . . . |
$$ | . X . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O . . . . . . . . . . . . . . . |
$$ | . 1 X O . X . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
This is why tiger mouth is joseki.
Amsterdam, soon.
Top
Uberdude
Judan
Posts: 6727
Joined: Thu Nov 24, 2011 11:35 am
Rank: UK 4 dan
GD Posts: 0
KGS: Uberdude 4d
OGS: Uberdude 7d
Location: Cambridge, UK
Has thanked: 436 times
Been thanked: 3718 times

Re: defending the corner

Post by Uberdude »

nickxyzt wrote: Could anybody point out what is the difference with the next diagram? What am doing wrong?
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O O . . . . . . . . . . . 3 . . . |
$$ | . 2 X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
2 is not 100% sente, black can choose to play 3 elsewhere depending how big other moves are.

The reason the hanging connection is (usually) better than solid is if white tenukis, then you can increase your territory and eyespace in sente (notice how :b1: means white can't capture :b3: if black now tenukis):
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . 4 . . . . . . . . . . . . . . . . . |
$$ | . 3 O O . . . . . . . . . . . 2 . . . |
$$ | . . X O . X . . . . . . . . . . . . . |
$$ | . 1 . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
If you just played solid, then you'd need to end in gote if you want to defend :b3:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . 4 . . . . . . . . . . . . . . . . . |
$$ | . 3 O O . . . . . . . . . . . 2 . . . |
$$ | 5 . X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The reason white should play atari as in your second diagram is it makes black's 2nd line move there gote instead of sente.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . 6 . . . . . . . . . . . . . . . . . |
$$ | . 5 O O . . . . . . . . . . . 4 . . . |
$$ | 7 2 X O . X . . . . . . . . . . . . . |
$$ | . 1 3 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
A more subtle advantage of the hanging connection over the solid is that it makes better eyeshape: Imagine white plays e3 as a ko threat and black ignores (or through some other fighting in this area black gets cut off here), he can live unconditionally in the corner:
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . 5 . . . . . . . . . . . . . . . . . |
$$ | . 4 O O . . . . . . . . . . . . . . . |
$$ | 6 O X O 1 X . . . . . . . . . . . . . |
$$ | . X X X 3 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
With the solid, it is only a ko for life in the corner (tripod group with extra leg):
Click Here To Show Diagram Code
[go]$$W
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . 5 . . . . . . . . . . . . . . . . . |
$$ | . 4 O O . . . . . . . . . . . . . . . |
$$ | 6 . X O 1 X . . . . . . . . . . . . . |
$$ | . . X X 3 . . . . . . . . . . . . . . |
$$ | . 7 . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
There is a possible advantage of the solid connection though, that is if you don't expect the additional eyeshape of the hanging connection to be useful and in the yose you wish to play this sente yose sequence. White can try to prevent black making this sente profit by exchanging b3 for b2 (if black ignores then white's block at b2 is big and sente to capture 3 stones) so that it reverts to the hanging connection shape with just the gote capture as black's yose here. Which of these outcomes is more likely basically comes down to who will have sente to start the endgame, which is not an easy thing to say.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | 4 6 . . . . . . . . . . . . . . . . . |
$$ | 3 2 O O . . . . . . . . . . . . . . . |
$$ | 5 1 X O . X . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Top
User avatar
drmwc
Lives in gote
Posts: 452
Joined: Sat Dec 01, 2012 2:18 pm
Rank: 4 Dan European
GD Posts: 0
Has thanked: 74 times
Been thanked: 100 times

Re: defending the corner

Post by drmwc »

To add one more point to Uberdude's excellent post, consider the effect of the following two moves:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 2 O O . . . . . . . . . . . , . . . |
$$ | . . X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
and:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 4 O O . . . . . . . . . . . , . . . |
$$ | . 2 X O . X . . . . . . . . . . . . . |
$$ | . 1 3 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The first diagram is potentially better yose for W, due the possibility of a 2-2 point attachement as follow up.
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 2 O O . . . . . . . . . . . , . . . |
$$ | . . X O . X . . . . . . . . . . . . . |
$$ | . 4 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
On alisghtly different strand, one yose move for W to watch out for is 4 below, which saves a couple of points:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | 4 . O O . . . . . . . . . . . , . . . |
$$ | . 3 X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
The reason is that B 7 below is now gote (dependent on the other yose on the board):
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . 6 . . . . . . . . . . . . . . . . . |
$$ | 4 5 O O . . . . . . . . . . . , . . . |
$$ | 7 3 X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Alternatively, B could play as follows but get 2 points less than when W descends for 4:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | 4 6 O O . . . . . . . . . . . , . . . |
$$ | 5 3 X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Top
User avatar
Dusk Eagle
Gosei
Posts: 1758
Joined: Tue Apr 20, 2010 4:02 pm
Rank: 4d
GD Posts: 0
Has thanked: 378 times
Been thanked: 375 times

Re: defending the corner

Post by Dusk Eagle »

drmwc wrote: Alternatively, B could play as follows but get 2 points less than when W descends for 4:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | 4 6 O O . . . . . . . . . . . , . . . |
$$ | 5 3 X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Although, if white tenukis for :w6:, the result is no different then if black had pushed at :w6: with :b5:, white blocked, black descended to :b5:, and white tenukis.
We don't know who we are; we don't know where we are.
Each of us woke up one moment and here we were in the darkness.
We're nameless things with no memory; no knowledge of what went before,
No understanding of what is now, no knowledge of what will be.
Top
User avatar
drmwc
Lives in gote
Posts: 452
Joined: Sat Dec 01, 2012 2:18 pm
Rank: 4 Dan European
GD Posts: 0
Has thanked: 74 times
Been thanked: 100 times

Re: defending the corner

Post by drmwc »

Dusk Eagle wrote:
drmwc wrote: Alternatively, B could play as follows but get 2 points less than when W descends for 4:
Click Here To Show Diagram Code
[go]$$B
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | 4 6 O O . . . . . . . . . . . , . . . |
$$ | 5 3 X O . X . . . . . . . . . . . . . |
$$ | . . 1 X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Although, if white tenukis for :w6:, the result is no different then if black had pushed at :w6: with :b5:, white blocked, black descended to :b5:, and white tenukis.
True.
Top
illluck
Lives in sente
Posts: 1223
Joined: Sun Apr 25, 2010 5:07 am
Rank: OGS 2d
GD Posts: 0
KGS: illluck
Tygem: Trickprey
OGS: illluck
Has thanked: 736 times
Been thanked: 239 times

Re: defending the corner

Post by illluck »

Uberdude, I don't quite agree with "The reason the hanging connection is (usually) better than solid is if white tenukis, then you can increase your territory and eyespace in sente" because white pretty much will never tenuki and black has to take gote to connect. I think the strength of the group is the most important determinant - if the group is strong then the connect is preferred due to the descent being sente later.
Top
Post Reply

Return to “Study Group”