It is currently Sat Feb 27, 2021 8:38 am

All times are UTC - 8 hours [ DST ]




Post new topic Reply to topic  [ 10 posts ] 
Author Message
Online
 Post subject: How is your positional judgement? Game 18
Post #1 Posted: Wed Oct 30, 2019 2:23 am 
Honinbo

Posts: 10660
Liked others: 3586
Was liked: 3337
As always, assume area scoring and 7½ pt. komi.

After :b31: Elf estimates one player's winrate as 93½% with 27.7k playouts. Which player is it?

Click Here To Show Diagram Code
[go]$$Bcm31 White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . O O X X . . . . . X . . O . X . . . |
$$ | . . . O . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . X X . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , X O . . . , . . . . . , . . . |
$$ | . . . X O O . . . O . . . . . O . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Enjoy! :D

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #2 Posted: Wed Oct 30, 2019 2:54 am 
Lives in sente
User avatar

Posts: 1136
Liked others: 91
Was liked: 389
Black has about 45 points of solid territory with two large corners, and no weak groups. White doesn't have many points on the top left, has some potential on the bottom, and one weak group. The shape of the three stones L15 is light, but I feel that White needs to add a defensive move, I don't know where (my kyu-level instinct indicates N12 or J14). Black will attack White and get stones in the center, which will help erase White's potential at the bottom.

So I choose Black.

Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #3 Posted: Wed Oct 30, 2019 3:03 am 
Judan

Posts: 6656
Location: Cambridge, UK
Liked others: 429
Was liked: 3651
Rank: UK 4 dan
KGS: Uberdude 4d
OGS: Uberdude 7d
Black, as most his stones look like ones Elf is reasonably ok with (e.g. distant approach for kosumi in top right better for black). c7 is maybe better at c8 given white played the attachment against corner (and lower side white is nicely efficient), but the top left is not an Elf favourite, c10 is weird, top right stones would be ok were it not for this terrible exchange in which white presumably hoped black would be a chicken and hane under but he didn't and that thick nobi weaknes the top 3 stones:

Click Here To Show Diagram Code
[go]$$Bcm31 White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . O O X X . . . . . X . . O . X . . . |
$$ | . . . O . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . B X . . . |
$$ | . . . . . . . . . . . . . . . W . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , X O . . . , . . . . . , . . . |
$$ | . . . X O O . . . O . . . . . O . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #4 Posted: Wed Oct 30, 2019 4:50 am 
Lives with ko

Posts: 218
Liked others: 23
Was liked: 14
Rank: IGS 3k
KGS: Bki
IGS: mlbki
Alright, let's look at what both players have :

Black :

The lower left corner is rock solid territory. So is the top group. The top right corner is solid and is mostly connected to the two stones lower down the right side. The Q10 stone is not yet isolated, but can't really be called connected. But it's a single stone in a large area, so it's not a burden.

The lower left and top group are worth roughly 20 points, the top right corner has more scope to be reduced but could easily end up being 10+ points. So I give black ~50 points of territory.

White :

The top left group is safe but not entirely connected with the C10 stone. The top side group is a bit loose. It's not exactly safe but it can probably afford to live by sacrificing a stone at worst. Finally white has an enclosed corner with a side moyo.

I think black is better as the board stand but it's white's move, so it depends on what he might be able to do with that. The "simple" option would be to try to secure the side territory, but then black can invade the corner (or get chased out and ruin white's everything), or, possibly even better, play a light reducing move against the side then invade the corner (it depends on how white might resist). Giving black the corner (and maybe 4-5 points there) and white the side, white seems to have maybe 40 points of territory counting the open-skirt, but that's maybe a bit optimistic depending on how much black can reduce.

Black can then bully a bit white's top group and solidify some more territory as a result, before launching an invasion of the left side. Then black should be ahead in territory and white has no way to get more.

So black seems to be ahead to me. There's just too many possibility to erase white's stuff.

Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #5 Posted: Wed Oct 30, 2019 5:35 am 
Lives with ko

Posts: 224
Liked others: 40
Was liked: 94
Rank: 2d
Black has some nice secure territories, and White has weaknesses. In particular, I don't believe White's left side is going to turn into very much territory, and the three stones in the top right are weak. That leaves only the lower side framework, and that is okay but not spectacular.
What happened on the right? We were just talking about elephant jumps, weren't we? This one looks rather badly damaged, and unless White can do something spectacular like descend with the isolated stone and live there, it kind of looks like a wasted move.
So I'm choosing Black, and I don't feel I have too much reason to second-guess myself here.

Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #6 Posted: Wed Oct 30, 2019 7:12 am 
Lives in gote

Posts: 498
Liked others: 1
Was liked: 149
Rank: KGS 2k
GD Posts: 100
KGS: Tryss
I also prefer black.

And what about Katago? He agree, and put white at 32%wr and -7pts (with 40k playouts)

Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #7 Posted: Wed Oct 30, 2019 7:30 am 
Lives with ko

Posts: 131
Liked others: 1
Was liked: 18
Rank: AGA 4 dan
Universal go server handle: telegraphgo
I don't have enough time to give a detailed analysis, unfortunately. It looks like white and black have generally been playing decent moves throughout most of the board. Then, for some reason, W was cautious to a fault in the upper right? W's territories require further moves, B's territories are perfectly strong due to nearby weak W groups. Since B looks a little bigger than W on top of that, I have to take black here.

Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #8 Posted: Wed Oct 30, 2019 7:51 am 
Gosei
User avatar

Posts: 1779
Location: Ghent, Belgium
Liked others: 271
Was liked: 824
Rank: KGS 2d OGS 1d Fox 4d
KGS: Artevelde
OGS: Knotwilg
Online playing schedule: UTC 18:00 - 22:00
No LZ

This one looks almost too easy. Black has good territory in three places AND White has three floating stones at the top. White has a large area for development at the bottom, but it can be reduced from above, invaded at the large knight's, and it's already undercut from the left.


LZ


Top
 Profile  
 
Online
 Post subject: Re: How is your positional judgement? Game 18
Post #9 Posted: Mon Nov 18, 2019 8:16 pm 
Honinbo

Posts: 10660
Liked others: 3586
Was liked: 3337
Game 18

Iwamoto Kaoru (W) vs. Fujisawa Kuransuke, Honibo League, September, 1950 (GoGoD 1950-98-22a)

The komi for the Honinbo Tournament was 4½ pts. at the time.

After :b31: Elf estimates Black's winrate as 93½% (27.7k playouts). Black won by 3½ pts.

Click Here To Show Diagram Code
[go]$$Bcm29 Black is ahead.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . O O X X . . . . . X a . O . X . . . |
$$ | . . . O . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . 3 X . . . |
$$ | . . . . . . . . . . . . . . . 2 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . b . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , X O . . . , . . . . . , . . . |
$$ | . . . X O O . . . O . . . . . O . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Elf thinks that :w30: is a mistake, losing 9% to the attachment at a. For :w32: Elf recommends the attachment at b, but the play from there is complicated, and Elf regards a, which Iwamoto played in the game, as only ½% worse, so I shall show Elf's continuation from there.

Click Here To Show Diagram Code
[go]$$Bcm33 Elf's continuation from :w32:, marked
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . 1 5 . . . . . . |
$$ | . O O X X . . . . . X W . O . X . . . |
$$ | . . . O . X . . X , . 2 . . . , X . . |
$$ | . . O . . . . 7 6 . O . . . . . . . . |
$$ | . . . 3 . . . . . . . . . O . . . . . |
$$ | . 4 . . . . . . . . . . . . X X . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , X O . . . , . . . . . , . . . |
$$ | . . . X O O . . . O . . . . . O . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:b33: is the underneath hane, to which White stands, solidifying his group. :b35: takes kikashi in the top left and then :b37: prevents White from making eye shape on the second line. The variation stops here, probably because the playouts for future play dropped below 1500.

Earlier in the game

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


:w6: is an error that loses 11½% to par, according to Elf. It is not that the ogeima approach is so bad, per se, it is that the 3-3 invasion at a in the bottom left corner is so good. The value of these early 3-3 invasions was not suspected before the advent of AI.

Elf's mainline variation for :w6:

Click Here To Show Diagram Code
[go]$$Wcm6 3-3 invasion
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , X . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 0 . . . . . . . . . . . . . . . |
$$ | . . 9 8 . . . . . . . . . . . . . . . |
$$ | . . 7 6 . . . . . . . . . . . . . . . |
$$ | . . 5 X . . . . . . . . . . . . . . . |
$$ | . . . 3 4 . . . . , . . . . . , . . . |
$$ | . . 1 . 2 . . . . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White invades the bottom left corner and claims territory while Black makes a sizable wall.

Click Here To Show Diagram Code
[go]$$Wcm16 3-3 invasion, continued
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . 4 , . 6 . . . , . . . 2 . , X . . |
$$ | . . O 5 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . 7 . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . 1 . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . O X . . . . , . . . . . , . . . |
$$ | . . O . X . . . . . 3 . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w16: encloses the bottom right corner. Then :b17: makes a two space high enclosure in the top right, which was not popular before the AI era. :w18: extends on the bottom side, reducing Black's influence there. The bots have devalued the sides, but each corner has at least two stones in it. Next, Black plays a kick joseki in the top left corner, another joseki that was not popular before the bot era. Then, :w22: jumps on the third line on the left side, making some territory and forming a 5 space extension from the two White stones in the corner. Dogma at the time was that such extensions are too far. The bots don't care.

Later in the game

Click Here To Show Diagram Code
[go]$$Bcm19 :b21: blunders
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . 0 O X 3 . . . . . X . . O . X . . . |
$$ | . . . 2 . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 9 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , 5 8 . . . , . . . . . , . . . |
$$ | . . . X 4 6 . . . O . . . . . O . . . |
$$ | . . . 7 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Elf says that the natural looking extension, :b21:, loses 19½% to par. :w22: switches to the third line attachment against the Black enclosure in the bottom left corner. :b27: secures territory in the bottom left co[rner. Then :w28: descends in the top leftcorner. Instead of :w26: Elf prefers 27 by 5½%.

Elf's recommended variation for :b21:

Click Here To Show Diagram Code
[go]$$Bcm21 Atari first
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . 1 O X 7 . . . . . X . . O . X . . . |
$$ | . . 6 O . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 8 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , 3 . . . . , . . . . . , . . . |
$$ | . . . X 2 4 . . . O . . . . . O . . . |
$$ | . . . 5 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w26: connects and :b27: extends. White could have played this exchange earlier. Comparing the two diagrams, it seems like the main point playing the atari at :b21: is this exchange.

Ironically, Elf regards the descent at :w28: as a blunder, losing 20%. ;) White has a superior play in the next diagram.

Click Here To Show Diagram Code
[go]$$Wcm28 Third line attachment
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . O X X . . . . . X . . O . X . . . |
$$ | . . . O . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . 9 . 0 . . . . . . . . . . . . . . . |
$$ | . . 1 2 . . . . . . . . . . . . . . . |
$$ | . 3 X a . . . . . . . . . . . . . . . |
$$ | . 7 4 . . . . . . . . . . . . . O . . |
$$ | . 8 . X . . . . . . . . . . . . . . . |
$$ | . . 5 6 X O . . . , . . . . . , . . . |
$$ | . . . X O O . . . O . . . . . O . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:w38: = a

:w28: plays a second third line attachment. :b29: plays the top hane. (If :b29: is at a, :w30: is the same.) After :w30: :b31: pulls back. The peep, :w32:, the crawl, :w34:, and the cut, :w38:, leave White some aji in the corner.

So Black and White traded blunders. Other than that, :w6: missed the 3-3 invasion, which was probably heresy at the time. Other than that, Black took a strong lead because of an accumulation of relatively small errors by White.

Edited typos.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.


Last edited by Bill Spight on Tue Nov 19, 2019 12:21 pm, edited 4 times in total.
Top
 Profile  
 
Offline
 Post subject: Re: How is your positional judgement? Game 18
Post #10 Posted: Tue Nov 19, 2019 12:38 am 
Judan

Posts: 6656
Location: Cambridge, UK
Liked others: 429
Was liked: 3651
Rank: UK 4 dan
KGS: Uberdude 4d
OGS: Uberdude 7d
Bill Spight wrote:
Click Here To Show Diagram Code
[go]$$Bcm19 :b21: blunders
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . 0 O X 3 . . . . . X . . O . X . . . |
$$ | . . . 2 . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 9 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , 5 8 . . . , . . . . . , . . . |
$$ | . . . X 4 6 . . . O . . . . . O . . . |
$$ | . . . 7 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Elf says that the natural looking extension, :b21:, loses 19½% to par. :w22: switches to the third line attachment against the Black enclosure in the bottom left corner. :b27: secures territory in the bottom left co[rner. Then :w28: descends in the top right corner. Instead of :w28: Elf prefers 29 by 5½%.

Elf's recommended variation for :b21:

Click Here To Show Diagram Code
[go]$$Bcm21 Atari first
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . 1 O X 7 . . . . . X . . O . X . . . |
$$ | . . 6 O . X . . X , . . . . . , X . . |
$$ | . . O . . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 8 . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , 3 . . . . , . . . . . , . . . |
$$ | . . . X 2 4 . . . O . . . . . O . . . |
$$ | . . . 5 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:w26: connects and :b27: extends. White could have played this exchange earlier. Comparing the two diagrams, it seems like the main point playing the atari at :b21: is this exchange.

Ironically, Elf regards the descent at :w28: as a blunder, losing 20%. ;)


I remember reading the opinion of Go Seigen (maybe in John's books) that against this bulge shape in the corner of :w20: black should essentially always atari. If we knew White we going to make the heavy empty triangle connection then I'm sure everyone would. But we expect White to counter atari and breaks through the side. That's a joseki too, but that Elf thinks the dumb connection (which teachers would tell you off for) is better than that trade shows we have misevaluated it. I think us humans, even top pros, tend to be too attached to the territory we are building on the top side and lack the flexibility to willingly give that up when White breaks through (but the counter argument is that it's consistent and avoids those stones becoming misplaced). But when that happens black gets good corner profit and the White group isn't thickness but still weak and attackable. Of course Go Seigen was known for his flexibility so was more willing to go for the complicated trade line spurrrd in by the desire to play the strongest local move.

Click Here To Show Diagram Code
[go]$$Bcm19 fighting spirit trade
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 6 . . . . . . . . . . . . . . . |
$$ | . 3 7 X 4 . . . . . X . . O . X . . . |
$$ | . . 5 2 8 X . . X , . . . . . , X . . |
$$ | . . O 9 . . . . . . O . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . X . . . . . O . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


P.S if White wants to get the bulge shape without giving black a good chance to resist then the 2nd line crosscut at d18 is a good tesuji for situations like this with black strong on the top side so you are happy to overconcentrate.


This post by Uberdude was liked by: Bill Spight
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 8 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group