Cutting point in 3-3 invasion joseki

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 1:02 am

A position from the interesting Malkovich game #158:

Click Here To Show Diagram Code: [go]$$Bcm11 W:0 B:0 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . X . . . . | $$ | . . . , . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . X . . . . . . . . . . . . b O X . | $$ | . . . , . . . . . , . . . . . O X . X | $$ | . . . X . . . . . O . . . 0 a O X . . | $$ | . . . . . . . . . . . . . . O X 9 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Probably a basic question, but why was :w20:

played here? Couldn't White play elsewhere, then if Black cut at A, trap him in an inescapable ladder by then playing that move? Why is cutting point A more important than cutting point B?

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 1:05 am

Don't worry, I have just seen it: Black can escape from the ladder by capturing the 2 Black stones!

EdLee · Post by **EdLee** » Sat Oct 13, 2012 1:07 am

Peter, first of all, :b15:

(T4) was a mistake, and not joseki.
The result is too good for W -- so don't learn this as a 'joseki'.
Second, could you show your sequence if B cuts at (b)?
This will answer your last question why W fixed (a) but not (b).

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 1:22 am

EdLee wrote:Peter, first of all, (T4) was a mistake, and not joseki.

That move looked odd to me, but I was giving the player (who is much stronger than I am) the benefit of the doubt. Thanks for pointing out something that I should NOT try to learn from.

EdLee wrote:Second, could you show your sequence if B cuts at (b)?
(This will answer your question why W fixed the cut at (a) but not at (b)).

I think I have answered my own question: Black can escape from a ladder at A, but not from one at B?

EdLee · Post by **EdLee** » Sat Oct 13, 2012 1:23 am

PeterPeter wrote:Black can escape from a ladder at A, but not from one at B?

It sounds like you figured out what happens if B cuts at (a).
Now please show us (and other beginners) the sequence you figured out if B cuts at (b).

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 1:42 am

Click Here To Show Diagram Code: [go]$$Bcm19 W:0 B:0 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . X . . . . | $$ | . . . , . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . 0 . . . . | $$ | . . . . . . . . . . . . . . 9 6 . . . | $$ | . . . . . . . . . . . . . 8 7 5 O O . | $$ | . . X . . . . . . . . . . . 4 3 O X . | $$ | . . . , . . . . . , . . . . . O X . X | $$ | . . . X . . . . . O . . . 2 . O X . . | $$ | . . . . . . . . . . . . . . O X 1 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Am I missing something? I don't see a good outcome for Black after :b21:

?

EdLee · Post by **EdLee** » Sat Oct 13, 2012 1:45 am

PeterPeter wrote:Am I missing something?

Yes.

Your sequence fails for W if there was a B stone at C17. Try again.

In other words, if we change to following board, W would still play :w1:

to fix (a), and not (b) -- why??

Click Here To Show Diagram Code: [go]$$W $$ ----------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O O . | $$ | . . . . . . . . . . . . . . . b O X . | $$ | . . . , . . . . . , . . . . . O X . X | $$ | . . . . . . . . . . . . . 1 a O X . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 2:02 am

Oh I see. I don't see an escape for Black from this net:

Click Here To Show Diagram Code: [go]$$W $$ ----------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . 3 . O O . | $$ | . . . . . . . . . . . . . . . 2 O X . | $$ | . . . , . . . . . , . . . . . O X . X | $$ | . . . . . . . . . . . . . 1 . O X . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

EdLee · Post by **EdLee** » Sat Oct 13, 2012 2:08 am

Very good! :clap:

Now you understand :w20:

better in that game.
Here is one joseki -- W also plays :w6:

to fix (a), but not (b) -- why?

Click Here To Show Diagram Code: [go]$$B $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . . . O 1 . | $$ | . . . . . . . . . . . . . . . b O X . | $$ | . . . , . . . . . , . . . . . O X . . | $$ | . . . . . . . . . . . . . 6 a O X . . | $$ | . . . . . . . . . . . . . . 4 3 5 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 2:18 am

This looks very similar. White could set a net at c.

Click Here To Show Diagram Code: [go]$$B $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 2 . . | $$ | . . . . . . . . . . . . . . c . O 1 . | $$ | . . . . . . . . . . . . . . . b O X . | $$ | . . . , . . . . . , . . . . . O X . . | $$ | . . . . . . . . . . . . . 6 a O X . . | $$ | . . . . . . . . . . . . . . 4 3 5 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

EdLee · Post by **EdLee** » Sat Oct 13, 2012 2:21 am

Good. Follow-up question: what about :w2:

? Can B escape with :b3:

?

Click Here To Show Diagram Code: [go]$$B $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . 3 O X . | $$ | . . . . . . . . . . . . . . 2 1 O X . | $$ | . . . , . . . . . , . . . . . O X . . | $$ | . . . . . . . . . . . . . O . O X . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 2:27 am

White would set a net with :w4:

.

Click Here To Show Diagram Code: [go]$$B $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . 4 . O . . | $$ | . . . . . . . . . . . . . . . 3 O X . | $$ | . . . . . . . . . . . . . . 2 1 O X . | $$ | . . . , . . . . . , . . . . . O X . . | $$ | . . . . . . . . . . . . . O . O X . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

EdLee · Post by **EdLee** » Sat Oct 13, 2012 2:28 am

Yes -- what if B ataris with :b5:

?

Click Here To Show Diagram Code: [go]$$B $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . 4 . O . . | $$ | . . . . . . . . . . . . . . . 3 O X . | $$ | . . . . . . . . . . . . . . 2 1 O X . | $$ | . . . , . . . . . , . . . . 5 O X . . | $$ | . . . . . . . . . . . . . O . O X . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

PeterPeter · Post by **PeterPeter** » Sat Oct 13, 2012 3:02 am

Click Here To Show Diagram Code: [go]$$B $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . b . . . | $$ | . . . . . . . . . . . . . . 4 a O . . | $$ | . . . . . . . . . . . . . . 7 3 O X . | $$ | . . . . . . . . . . . . . . 2 1 O X . | $$ | . . . , . . . . . , . . . 8 5 O X . . | $$ | . . . . . . . . . . . . . O 6 O X . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

White will connect with :w6:

, then Black can escape at :b7:

(escaping at A fails after White B). White will capture with :w8:

, and I slightly prefer White's position.

I had to consider a lot of variations to decide on this main line - how did I do?

EdLee · Post by **EdLee** » Sat Oct 13, 2012 3:14 am

was bad -- try again.

PeterPeter wrote:White will capture with , and I slightly prefer White's position.
$$B
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 4 . O . . |
$$ | . . . . . . . . . . . . . 9 7 3 O X . |
$$ | . . . . . . . . . . . . . . 2 1 O X . |
$$ | . . . , . . . . . , . . . 8 C O X . . |
$$ | . . . . . . . . . . . . . O 6 O X . . |
$$ | . . . . . . . . . . . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ -----------------------------------------

Click Here To Show Diagram Code
[go]$$B $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . 4 . O . . | $$ | . . . . . . . . . . . . . 9 7 3 O X . | $$ | . . . . . . . . . . . . . . 2 1 O X . | $$ | . . . , . . . . . , . . . 8 C O X . . | $$ | . . . . . . . . . . . . . O 6 O X . . | $$ | . . . . . . . . . . . . . . O X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ -----------------------------------------[/go]

This shape is a disaster for W.

Life In 19x19

Cutting point in 3-3 invasion joseki

Cutting point in 3-3 invasion joseki

Re: Cutting point in 3-3 invasion joseki

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Re: Cutting point in 3-3 invasion joseki

Re: Cutting point in 3-3 invasion joseki

Re: Cutting point in 3-3 invasion joseki

Re: Cutting point in 3-3 invasion joseki

Re: Cutting point in 3-3 invasion joseki