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Shapes to remember (SDK level)
http://lifein19x19.com/viewtopic.php?f=48&t=16894
Page 5 of 5

Author:  jlt [ Wed Apr 07, 2021 2:10 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Further Katago variations on my third hidden diagram.

Suppose that Black plays :b5: at B17, then Katago thinks the only move for :w6: is B16.

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


Click Here To Show Diagram Code
[go]$$Bcm7 :w14: at a or b
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . . 2 . . . . . . . . . . . . |
$$ | . O O O O . . . . , . . . . . X . . . |
$$ | . . . . . . a . . . . . . . . . . . . |
$$ | . . X . X . b . . . . . . . . . . . . |
$$ | . . . 1 . . . . . . . . . . . . . . . |
$$ | . . O 3 O . . . . . . . . . . . . . . |
$$ | . . . 4 5 7 . . . . . . . . . . . . . |
$$ | . . O , 6 . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


Instead of peeping, Black may want to continue jumping.

Click Here To Show Diagram Code
[go]$$Bcm7 Running fight
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X 5 . . . . . . . . . . . . |
$$ | . X X X . . 2 . . . . . . . . . . . . |
$$ | . O O O O . . 4 . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . a X . X . 1 . . . . . . . . . . . . |
$$ | . . . 3 . . . . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . 6 . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


In the above diagram, White may want to connect underneath at "a" for :w8:, this is slightly less good.

In any case, Black cannot push and cut

Click Here To Show Diagram Code
[go]$$Bcm7 bad for Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . 3 2 . . . . . . . . . . . . |
$$ | . O O O O 4 5 7 9 , . . . . . X . . . |
$$ | . . . . . . 6 8 . . . . . . . . . . . |
$$ | . a X . X . 1 . . . . . . . . . . . . |
$$ | . . . . . . 0 . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


White can save the 5 stones with "a" at any time.


Edit: last diagram corrected.

Author:  jlt [ Thu May 13, 2021 2:53 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Really a shape problem.

Position #49, White to play. What is White's next move, and what is the continuation?

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


Answer:

Click Here To Show Diagram Code
[go]$$Wc Katago's answer
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X X O |
$$ | . . X O . . . . . . X X . X . O X O . |
$$ | . . X O . . . . . , . O . X . X O O O |
$$ | . . . O . . . . . . O . O X . X X O . |
$$ | . X . . . . . . . . O O X X X O O O . |
$$ | . . . . . . . . . . . X O O O X X . . |
$$ | . . . . . . . . . . b X . . . O X . . |
$$ | . . . . . . . . . . . 3 . 1 . 2 . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . a . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . O O O . . . , . . . . X , . . . |
$$ | . . O X O X X . . . . . . . . X . . . |
$$ | . . X X X . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White cannot kill the three stones, at least not immediately. :w3: strengthens the three white stones so that White can aim at attacking one of the black groups later. For instance if Black doesn't defend the group on the right, then "a" will be a good point for White. If Black doesn't defend the two stones then "b" will be a good point for White.

Author:  Bill Spight [ Fri May 14, 2021 6:48 am ]
Post subject:  Re: Shapes to remember (SDK level)

Edit: Nevermind. :D

I assume that the following is the correct diagram for the last one in #81..

Click Here To Show Diagram Code
[go]$$Bcm7 bad for Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . X X X . 3 2 . . . . . . . . . . . . |
$$ | . O O O O 4 5 7 9 , . . . . . X . . . |
$$ | . . . . . . 6 8 . . . . . . . . . . . |
$$ | . a X . X . 1 . . . . . . . . . . . . |
$$ | . . . . . . 0 . . . . . . . . . . . . |
$$ | . . O . O . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |[/go]


White can save the 5 stones with "a" at any time.

Author:  jlt [ Fri May 14, 2021 7:33 am ]
Post subject:  Re: Shapes to remember (SDK level)

Yes indeed, there were two :w12: in the diagram, I forgot to erase one. I edited my post according to your comment.

Author:  jlt [ Fri Jun 11, 2021 3:40 am ]
Post subject:  Re: Shapes to remember (SDK level)

Position #50, White to play. Shouldn't be hard but I missed it.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . O . X X X X X . O . . . . |
$$ | . . . O X . O X X O O O . X O . . . . |
$$ | . . O , O . . O O , . . . X . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . X . . . . . . . . . . . . . O X . |
$$ | . . . . . . . . . . . . . . . . O X . |
$$ | . X . O . . . . . , . . . . . , O X . |
$$ | . X O . . . . . . . . . . . . . . X . |
$$ | X . X O . . . . . . . . . . . O O O X |
$$ | . X . . . . . . . X X . X O . O X X . |
$$ | X O O O . O . . O X O X . X O X X . . |
$$ | . X X . . . O O X O O O X . O O X . . |
$$ | . . . X X X O X X X . . X X O X . . . |
$$ | . . O X O O X . X . O O . . X X . . . |
$$ | . O . O O O X . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Answer:

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

Author:  jlt [ Fri Jun 11, 2021 10:56 pm ]
Post subject:  Re: Shapes to remember (SDK level)

Yet another simple move.

Position #51, White to play. There are several possible good moves, the question is how to attack/put pressure on the group K16.

Click Here To Show Diagram Code
[go]$$Wc White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . . . . . . . . . X . . . . . . O |
$$ | . . . O . . O . . X . . . O . O O O X |
$$ | . . . . . . . . . . . . . . . . X X X |
$$ | . . . . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O . . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Answer:

In fact, many good moves are available on the board:

Click Here To Show Diagram Code
[go]$$Wc Possible moves
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . . . . . b a . . X . . . . . . O |
$$ | . . . O . . O . . X . . . O . O O O X |
$$ | . . d . . . . . . . . . . . . . X X X |
$$ | . . e . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . c . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O f . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I am mostly interested in move "a" which attacks Black's shape. Katago expects Black to just answer and then White takes a big point elsewhere.

Click Here To Show Diagram Code
[go]$$Wc continuation of move a
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . O . |
$$ | . . . . . . . . 1 2 . X . . . . . . O |
$$ | . . . O . . O . . X . . . O . O O O X |
$$ | . . . . . . . . . . . . . . . . X X X |
$$ | . . 3 . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O . . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


For move :w3:, White shouldn't make a move around N17: the upper right corner doesn't need to be protected since it is completely alive (for instance, a black move at O18 wouldn't be sente), and since Black has strenghthened his group with :b2:, a white move around N17 won't put a lot of pressure so Black won't respond.

Black can't play :b2: at O18, otherwise we get the following sequence:

Click Here To Show Diagram Code
[go]$$Wc continuation of move a (2)
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . 7 8 6 2 . . . O . |
$$ | . . . . . . . . 1 . 9 X 3 5 . . . . O |
$$ | . . . O . . O . . X 0 b 4 O . O O O X |
$$ | . . . . . . . . . . . . a . . . X X X |
$$ | . . . . . . O . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . c . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . O . . . . . . . . . . . . . . X X . |
$$ | O . O . . . . . . . . . . . . X . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , O . . . . X . . . |
$$ | . X O X . . . . . . . O O O . . . . . |
$$ | . X O . . . . . . . . . X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


and then White a, Black b, White c follow.

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