Footsweep shape question.

peppernut · #1

I have a local shape question after a footsweep. We can come to the shape where we have a head-of-two situation, but white has a kosumi already on the board:

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

If it were white to move, the hane at the triangled point is the shape move. Black's hane would be vulgar, so I think black can play at the triangle square himself, or make a 1 point jump. Regardless which is better - black "owes" a move here for local shape.

What happens if black already has the following marked stone:

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

It seems like black can just tenuki here. But then :w1:

is sente for White (I think), and a to be it looks like an inefficient, silly shape for black. What did White lose? Well the sansan invasion, but when White chose the footsweep he already stengthened Black, so that probably wasn't White's plan anyway. The approach on the upper side is still possible, as is a 2-4 invasion. Seems like White just strengthened his side for free.

Instead if Black shouldn't tenuki, a 1 point jump seems right. but it's still kind of overconcentrated, and the footsweep becomes sente.

It makes me wonder why I don't see more of these footsweeps after Black plays the original 3rd line move to threaten White's side. Intuitively I feel like I am missing something, but I can't see it.

lovelove · #2

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

White's hane is not sente and is also a bad exchange. Black's response is not in a bad shape, it is a very solid shape. White needs to extend, or black's atari at white's extension point will be painful.

Black usually don't play this way if there is no helping stone around for white. Marked points on the next diagram are black's usual response for the footsweep.

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

lovelove · #3

Footsweep usually appears with the Chinese fuseki.

Click Here To Show Diagram Code: [go]$$Bm1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . a . . . . O . . O . . X . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . 2 . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 4 5 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 3 . . . . . , . . . . . , X X . | $$ | . . . . . . . . . . . . . . . . X O . | $$ | . . . . . . . . . . . . . . . X . O . | $$ | . . . . . . . . . . . . . . O O O . . | $$ | . . O . . . . . . . . . . X X O . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . O . . . . . X . . . X . , O . . | $$ | . . . . . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . . X X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Bm1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . a . . . . O . . O . . X . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . 2 . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . X . . . | $$ | . . . 4 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 3 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . , . . . . . , X X . | $$ | . . . . . . . . . . . . . . . . X O . | $$ | . . . . . . . . . . . . . . . X . O . | $$ | . . . . . . . . . . . . . . O O O . . | $$ | . . O . . . . . . . . . . X X O . . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . O . . . . . X . . . X . , O . . | $$ | . . . . . X . . . . . . . . . X O . . | $$ | . . . . . . . . . . . . . . . . X X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

W L17 stone prevents black responding around "a" for the footsweep.

ez4u · #4

A couple of pro cases. As always, YMMV. :salute:

Click Here To Show Diagram Code: [go]$$Wc Shen Jing - Zhang Xuan, 1996-05-22 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . O . . X . . . . . . X . . . . . . | $$ | . . . O . . . X . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . O . O . . | $$ | . . 0 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X . . . | $$ | . . . , . . . . . , . . . . O O O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . X . X . X . . | $$ | . . . . . . . . . . . . . . X . . . . | $$ | . . O . . . . . . . O . . O O X . . . | $$ | . . . 5 . . . . . . . . . . . . . . . | $$ | . . . O 4 . . X . , . . . . O , X . . | $$ | . . . . 3 X . . . . X 8 O . . O O X . | $$ | . . 7 . 1 2 . . . . . . 9 . . . . X . | $$ | . . . . 6 . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Bc An Cho-yeong - Kang Tong-yun, 2006-10-13 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . O 1 . . . . . . . . . . . X . | $$ | . . . . 6 X . . . . X . O . . O O X . | $$ | . . . O . 8 9 X . , . . . . O , X . . | $$ | . . . . . 0 . . . . . . . . . O X . . | $$ | . . O . . . . . . . . . . O O X X . . | $$ | . . . . . . . . . . . . . . X O . . . | $$ | . . 5 . . . . . . . . . . . X . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . 3 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . X X . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . 4 . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . X . . . . . | $$ | . . . O . . . . . , . . O X . X O . . | $$ | . . . . . 2 . 7 . . . . X O X . O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

peppernut · #5

Thanks, this is interesting. Really helpful to see that Black's shape isn't overconcentrated, and white needs an extra move there at the end.

I wasn't clear I think about the original sweep. In the game that it happened, I had the corner and I was the one on the receiving end of the sweep:

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

The exchange 2 and 4 for 3 is good for Black I believe, since it help black strengthen his corner,

If 6 and 7 are also fine for black, and good shape, and most of all that White needs to fix at 8, then that explains further why we don't see a footsweep in such positions.

lovelove · #6

peppernut wrote:

...
then that explains further why we don't see a footsweep in such positions.

Footsweep is usually seen in modern pro games with similar situation on the diagram below.

Click Here To Show Diagram Code: [go]$$Bcm1 Marked position for black's next response $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . O . . . . . . . . . | $$ | . . . O . . . . . , . . . . . , . . . | $$ | . 2 . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . B B . . . . . . . . . . . . . . . | $$ | . . . B . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Loons · #7

A joseki. NB the footsweep can also lead to hard variations.

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

Footsweep shape question.

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