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 Post subject: Re: Shapes to remember (SDK level)
Post #21 Posted: Mon Dec 16, 2019 1:22 am 
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Position #12.

In this game, I was white, 7k EGF, playing against 2k EGF. This game showed how weak my endgame is: Katago estimates that I was leading by 10 points/91% winrate at move 147, and yet I lost by 15.5 points. :shock:

White to play and make a good endgame move.

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


Katago says that White should start with the exchange a-b, then play c.
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . . . . X . . . . . . . . |
$$ | . . . a b . X . X X O O O . . . . . . |
$$ | . . O X . . O X X O X O . O . . O O . |
$$ | . . O X . X X O O O X O X . O O X X . |
$$ | . O X . . . O . . X X . . . . X . X . |
$$ | . O X . . . . . O . . O O X . X X . . |
$$ | . O X . . . . . O . . . O O X . X X . |
$$ | O X X . X X O . . . . . . Y O O . O O |
$$ | . O X O O X O . . . . d . . . . O X . |
$$ | . O . , X O . . . , . . . . O , X . X |
$$ | . . . X X O . O . O . B . . . . . X . |
$$ | . . X . X O . . . . . . . . c X . . . |
$$ | . . X X O X X . X . . . . . . . . . . |
$$ | . . X O O . . . . . X . . . . . X . . |
$$ | . X X X X X . O O O O . . . . . . . . |
$$ | . X O O O O . O X X O O . . . O . X . |
$$ | . O O X X . O X X X X O . O . . O . . |
$$ | . . . . . X X O O X . X O . . . . . . |
$$ | . . . . . . . . . . X . . . . . . . . |
$$ ---------------------------------------[/go]


My reasoning was that :bc: threatens to enter my moyo, and at the same time to pull out the :bt: stone, so I protected at d. Katago says it loses "5 points". A better way of playing is to make sente moves starting with "c", which threaten to swallow :bc:, and protect the moyo afterwards. There are several lines of play, here is a simple one:

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


Last edited by jlt on Mon Dec 16, 2019 6:10 am, edited 1 time in total.
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 Post subject: Re: Shapes to remember (SDK level)
Post #22 Posted: Mon Dec 16, 2019 2:13 am 
Gosei
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What I learnt from pro games is that in the early endgame it's not so much about points but about life and death. In the late endgame it's easier to calculate what is sente and what is the biggest gote. In the early endgame there are so many mutual implications that this is harder. So one first needs to identify the areas where there is or will be major impact on groups, whether they are immediately sente or not.

Attemmpt:

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


The border plays that jump to the eye are A and B. A s simply large. B may have that particular quality of impacting the life of the corner group. At first glance if Black plays there it will be sente or at least have large follow-ups.

There is aji to exploit at C and D but nothing major and these moves may be kind of miai.

There are cuts at E and F to make something of the center, but it's probably small.

And then there is G. It makes 6 points already, the shape becomes better, and most of all it cuts Black into two groups. Now both of them are alive but later White will have sente moves against both of them.

I'm not sure this is the best move, but when leading it seems good enough to ensure victory.

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 Post subject: Re: Shapes to remember (SDK level)
Post #23 Posted: Mon Dec 16, 2019 3:06 am 
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@Knotwilg: I didn't try all your moves, but according to Katago, "b" is not bad, while "a" and "g" are even worse than the move I played in my game.

Here is the game, in case someone would be interested.



Attachments:
game.sgf [1.96 KiB]
Downloaded 100 times
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 Post subject: Re: Shapes to remember (SDK level)
Post #24 Posted: Mon Dec 16, 2019 6:16 am 
Gosei
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jlt wrote:
@Knotwilg: I didn't try all your moves, but according to Katago, "b" is not bad, while "a" and "g" are even worse than the move I played in my game.


To be fair to myself, I thought B was too trivial to be worthy of exercise, so I looked for something more interesting. With hindsight G is not sente and neither will it bring about much sente against any of the separated groups. B is a sente border play for Black and White has a good follow-up if Black doesn't answer.

Nice endgame exercise!

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 Post subject: Re: Shapes to remember (SDK level)
Post #25 Posted: Thu Jan 02, 2020 8:53 am 
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Position #13: this one should be obvious but both players, IGS 6k, got it wrong.

Black to play. What are the next few moves?

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


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


And then tenuki! Losing sente so early in the game by capturing at T11 is evil!

(In the actual game, Black captured at T11, which is 4-point mistake according to Katago, but then White protected the cut at P10, which is an equally big mistake...)

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 Post subject: Re: Shapes to remember (SDK level)
Post #26 Posted: Thu Jan 02, 2020 9:39 am 
Dies with sente

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Universal go server handle: telegraphgo
I thought this was going to be about black trying this common shape:

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


If white backs off at S8, this is an improvement on the game. So a fight's about to go down! But unfortunately, black doesn't have the strength to do this here. How does white win the fight?

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


Compared to the game variation, black is worse and white is better. It's a disaster. The reason things fell apart was white's one random stone at R14 enabling a ladder that forces black to play 2 as shown instead of at a. The followup at a was black's intent when they extended under like this - preventing it means white is better. This is such a clean example of middlegame fighting shape, I was positive it was close to the game until I opened your hide tag :lol:


This post by TelegraphGo was liked by: jlt
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 Post subject: Re: Shapes to remember (SDK level)
Post #27 Posted: Wed Jan 15, 2020 2:04 am 
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Position #14: this one should be easy. Edit: I forgot to say that it was White to move, thanks dfan.

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


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


Split Black into two weak groups. Yes there is a cut at a, but it is not urgent right now.


Last edited by jlt on Wed Jan 15, 2020 7:30 am, edited 1 time in total.
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 Post subject: Re: Shapes to remember (SDK level)
Post #28 Posted: Wed Jan 15, 2020 6:19 am 
Gosei

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White to move, for anyone was wondering but didn't feel like counting the stones.

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