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 Post subject: Shapes to remember (SDK level)
Post #1 Posted: Fri Aug 30, 2019 2:49 am 
Lives in gote
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In this thread I will post a few positions that occurred in my games, in which the best move (according to LZ) doesn't require reading to be found, but didn't cross my mind (I am 4k on KGS and on Fox).

Here, White should play at "a". If White doesn't, Black has some forcing moves that threaten to surround White while building influence.

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


Here, Black is surrounded. Playing at "a" secures the group while building a large corner.
Click Here To Show Diagram Code
[go]$$
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . . . . X . . . . . X . X O . . |
$$ | . . . X . . . . . O . X . . . X O O O |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . O . . O . . O . . . . . . . . . |
$$ | . . . . O . . . . . . O . . . O . X . |
$$ | . . . X X X . . . . . . . . . . X . . |
$$ | . . X . . . . X X X X . . . . O O X . |
$$ | . . . , O X X O O O O O . . . O X . . |
$$ | . . X O . O O X . . . . . . . O X . . |
$$ | . . . a . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


This post by jlt was liked by: Bill Spight
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 Post subject: Re: Shapes to remember (SDK level)
Post #2 Posted: Fri Aug 30, 2019 3:04 pm 
Judan

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I'm guessing in the first diagram black's previous move was approach at bottom left, and it should have been a? But o4 is not efficient then...

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 Post subject: Re: Shapes to remember (SDK level)
Post #3 Posted: Sat Aug 31, 2019 1:48 am 
Lives in gote
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The previous move was indeed approach on the bottom left. Instead of that move, LZ157's main line is the following, but I don't understand the purpose of the exchange :b1: :w2:.

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

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 Post subject: Re: Shapes to remember (SDK level)
Post #4 Posted: Sat Aug 31, 2019 3:27 am 
Lives with ko

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It's similar to peeping a tiger mouth: having a black stone here for free gives black better options later while not helping white much.

Forcing moves are an advanced concept. SDK players tend to play many sente moves, because they see them as forcing moves and thus good. But often they are aji-keshi and thus bad.

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 Post subject: Re: Shapes to remember (SDK level)
Post #5 Posted: Sat Aug 31, 2019 5:24 am 
Honinbo

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jlt wrote:
The previous move was indeed approach on the bottom left. Instead of that move, LZ157's main line is the following, but I don't understand the purpose of the exchange :b1: :w2:.

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


It's a case of get it while you can. If Black waits until White plays at a, White will not respond at :w2: to :b1:. In fact, Black will not play at 1 in that case.

The exchange, :b1: - :w2: is also why White does not play :w4: at a. It does not accomplish so much, now.

I would be happy to find :b1: in this position. :)

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 Post subject: Re: Shapes to remember (SDK level)
Post #6 Posted: Sun Sep 01, 2019 11:30 am 
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Position 3 : this one should have been obvious, and yet I missed it :oops:. White to play.

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



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


(and not D17, otherwise F18 would be sente. Then maybe Black is dead ?)

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 Post subject: Re: Shapes to remember (SDK level)
Post #7 Posted: Sun Sep 01, 2019 1:09 pm 
Gosei

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Yay, I got one! Further discussion hidden so as not to spoil.
By the way, this sort of pulling back to make a hane-connection one point (or more) farther back but with much better shape is something that I was never really taught explicitly, but often shows up in make-the-proper-move problems.

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

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

Here it's pretty clear why it's better for tactical reasons, but even when there isn't a clear tactical refutation to the greedier move, the shape move is generally much better.

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 Post subject: Re: Shapes to remember (SDK level)
Post #8 Posted: Fri Sep 06, 2019 9:02 am 
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Black to play.

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


Hint:
Where to invade on the left side?

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


The answer is to invade at :b1:. I invaded at "a", thinking that the upper group is weaker than the lower one, but this is wrong because of the stone :bt: that can help the invading stone.

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 Post subject: Re: Shapes to remember (SDK level)
Post #9 Posted: Sun Sep 08, 2019 11:28 am 
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Position #5: LZ proposes several moves but I didn't find any of them. White to play.

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


The upper white group can't escape easily. Better extend eyespace with sente moves first, and then
capture the two black stones.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . 3 1 O . X X 5 O X X O . |
$$ | . . . . . . 4 2 X . O . O O . X O O . |
$$ | . . . X . . . . . , . . . . . X X O . |
$$ | . . . . . . . . . . . . . . X . X O . |
$$ | . . . . . . . . . . . . . . . X O O . |
$$ | . . . . . . . . . . . . . . X . X O . |
$$ | . . . . . . . . . . X X X . X . X O . |
$$ | . . . . . . . . O O O O O O O X . X O |
$$ | . . . , . . . . . X O . O X X X O O . |[/go]


Another sequence considered by LZ: sacrifice the group to get moves in the center.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . 2 O . X X . O X X O . |
$$ | . . . . . . . . X 6 O 9 O O . X O O . |
$$ | . . . X . . . . . 5 4 8 . . . X X O . |
$$ | . . . . . . . . . 1 7 . . . X . X O . |
$$ | . . . . . . . . 3 . . . . . . X O O . |
$$ | . . . . . . . . . . . . . . X . X O . |
$$ | . . . . . . . . . . X X X . X . X O . |
$$ | . . . . . . . . O O O O O O O X . X O |
$$ | . . . , . . . . . X O . O X X X O O . |[/go]


This post by jlt was liked by: Bill Spight
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