Good response to 3-3 invasion

Shawn Ligocki · #1

What's the appropriate response to this invasion:

Click Here To Show Diagram Code: [go]$$Bc $$ --------------- $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . 1 3 4 O . . . $$ | 7 5 2 O . . . . . $$ | . 6 . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Specifically, I did not expect :b7:

, instead I expected this sequence:

Click Here To Show Diagram Code: [go]$$Bc $$ --------------- $$ | . . . . . . . . . $$ | . 7 . . . . . . . $$ | 9 . 1 3 4 O . . . $$ | 8 5 2 O . . . . . $$ | . 6 . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Looking at the game I cannot figure out what I should have done to punish :b7:

, though. This is the best I can read:

Click Here To Show Diagram Code: [go]$$Wcm8 $$ --------------- $$ | . . . . . . . . . $$ | 5 1 3 4 . . . . . $$ | . 2 X X O O . . . $$ | X X O O . . . . . $$ | . O b . . . . . . $$ | . a . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Which seems like Black might die ... but I can't exactly read it out. Especially because of the aji at a and b.

Anyone have any advice on what to do in this situation?

Bill Spight · #2

Click Here To Show Diagram Code: [go]$$Wcm8 $$ --------------- $$ | . 6 . . . . . . . $$ | 5 1 3 4 . . . . . $$ | . 2 X X O O . . . $$ | X X O O . . . . . $$ | . O b . . . . . . $$ | . a . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

looks like it makes seki, at least.

EdLee · #3

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

Bill & Shawn, Locally, how about :w1:

? Globally, it depends on the board ?

( Shawn, :bc:

=

is a common beginner bad habit. )

illluck · #4

EdLee wrote:

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

Bill & Shawn, Locally, how about :w1:

? Globally, it depends on the board ?

( Shawn, :bc:

=

is a common beginner bad habit. )

I don't think that's the answer as then black lives unconditionally in corner (which is better than the ko with correct play) when he made a mistake.

Bill Spight · #5

EdLee wrote:

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

Bill & Shawn, Locally, how about :w1:

? Globally, it depends on the board ?

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

Because of the weakness at "a" in the first diagram, the second is better for Black.

So if White would play :w1:

in the second diagram, it is even better in the first diagram.

Edit:

xed_over · #6

Bill Spight wrote:

(hidden continuation from hidden variation in post #2)
this result is bad for Black.

this phrase puzzles me sometimes... because black lives now, no? You're just saying black could've done better than living? Because in the initial variation, I thought black died. How can black do better than living, if he was previously dead (unless, of course, we're talking about the whole board now -- which is a giant unknown. Maybe the rest of the board is settled, and the outcome of the game now hinges solely on this local position)?

Bill Spight · #7

xed_over wrote:

Bill Spight wrote:

(hidden continuation from hidden variation in post #2)
this result is bad for Black.

this phrase puzzles me sometimes... because black lives now, no? You're just saying black could've done better than living? Because in the initial variation, I thought black died. How can black do better than living, if he was previously dead (unless, of course, we're talking about the whole board now -- which is a giant unknown. Maybe the rest of the board is settled, and the outcome of the game now hinges solely on this local position)?

Well, of course, the whole board matters.

Edit:

We can also compare the position in question with these, where Black also gets the last move.

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

Click Here To Show Diagram Code: [go]$$Bc $$ --------------- $$ | . . . . . . . . . $$ | . 1 . . . . . . . $$ | 3 . X X O O . . . $$ | 2 X O O . . . . . $$ | 9 O . . . . . . . $$ | . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

White gets a play elsewhere in exchange for losing the ko fight. OC, how much that move is worth is a question, but it will generally be less than the value of White's thickness in the hidden position.

Click Here To Show Diagram Code: [go]$$Bc $$ --------------- $$ | . . . . . . . . . $$ | 0 1 . . . . . . . $$ | 3 4 X X O O . . . $$ | 2 X O O . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Black gets a move elsewhere to let White win the ko, and then another to make the comparison with the other positions where Black moves last. Generally, these two moves will more than make up for not living in the corner.

Depending on the rest of the board, there may be situations where the hidden position is not as bad for Black as others that White can choose, but I still think that we can classify it as bad for Black.

Shawn Ligocki · #8

Thanks for the idea Bill, E19 is a cool connection, I've never seen that before and will have to keep it in mind (sort of a reverse monkey jump). It sounds like I have to choose between giving Black aji at B14 or letting Black live.

Here's the whole board position for those interested:

Click Here To Show Diagram Code: [go]$$Bc $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X X O O . . . . . . . . . . . . . | $$ | X X O O . . . . . X . . . . . X . . . | $$ | . O . . . . . . . . . . X . . . X X . | $$ | . . . . . . . . . . . . . . . O O X . | $$ | . . . . . . . . . . . . . . . O . O . | $$ | . . . . . . . . . . X . . . X O X O . | $$ | . . . . . . . . . . . . O O O X X X . | $$ | . . . O . X . . . , . . X X X O O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . X . X . | $$ | . . O O . . . . . . . . . . X O O O . | $$ | . . X . . X . . . . . . . . X O X X . | $$ | . . . X . . . . . , . . . O O X . . . | $$ | . . . . . . . . . O . . . O X X X X . | $$ | . . . . . . . . . . . . . . O O O O . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

In the game I protected the cut and Black lives in gote.

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

SmoothOper · #9

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

Bill Spight · **#10**

Click Here To Show Diagram Code: [go]$$Wcm8 $$ --------------- $$ | . 4 3 . . . . . . $$ | . 2 . . 1 . . . . $$ | . . X X O O . . . $$ | X X O O . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Bill Spight · **#11**

I guess I should have shown this before.

Shawn Ligocki · **#12**

I just chatted with In-seong Hwang 8d and he mentioned this cool move:

Click Here To Show Diagram Code: [go]$$Wc $$ --------------- $$ | . . . . . . . . . $$ | 1 . . . . . . . . $$ | . . X X O O . . . $$ | X X O O . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Now Black is in a lot of trouble. She must defend the cut, but both continuations are dead:

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

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

Of course, there is still aji at a in the first continuation.

:w1:

is a pretty cool move I hadn't seen before (threatens snapback).

leichtloeslich · **#13**

My first instinct:

Click Here To Show Diagram Code: [go]$$Wc $$ --------------- $$ | . . . . . . . . . $$ | 1 . . . . . . . . $$ | . . X X O O . . . $$ | X X O O . . . . . $$ | a O b . . . . . . $$ | . 2 . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Now a and b are kind of miai. Notice that if white b black a, the snapback thingy doesn't work anymore.

Dusk Eagle · **#14**

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

This works if you just want the corner and are okay giving up the outside.

Good response to 3-3 invasion

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