Life In 19x19

John Fairbairn wrote:

Edit: Widening our scope a little beyond the corner, if we pair on F-03 with on E-02, Black's pincer (I assume), on H-03, is much too close to the Black strength in the corner. Taking the corner has made Black's overconcentration even worse.

There's always a danger that tewari can be too local.

Indeed. But it can give us a local evaluation. If you can do a tewari on the left side as a whole, be my guest.

And the more I look at the aji of C11 after Black's corner capture (and knowing how pros always seem to wrest more from aji than I ever dream of) the more I think White cannot afford to be complacent about a future cut at G9. At the very least, I suspect, White is going to have to contrive to play an extra move on the left side.

To be sure, if Black takes the corner he may be able to gain something from sacrificing the Black stone on C-08. (Not that this Black is capable of such a sacrifice, however. ) But it would have to be enough to overcome the extra stone or two that he has wasted by taking the corner. That is unlikely, even with very good play. (Not counting on Black to play better than White, OC. ) Besides, since White has the move, White might play something like the one space jump to E-14, if the left side is a concern.

The discussion on the aji(?) around C8 reminds me a little bit of the discussion on what is considered "thick" from another thread.

It is a good point that professionals, compared to amateurs, may very well be better at exploiting aji, and also in showing that positions that are seen to be thick are not actually thick.

For this reason, yes, we must question our judgment as amateurs when we think something is thick. We should question our judgment when we think that there is little aji to exploit in a position. After all, we could be wrong- we are only amateurs.

That being said, this does not mean that our judgment is always wrong. Just because pros are good at exploiting aji, it does not mean that we always underestimate the aji that's present.

We cannot base decisions off of this.

Take another example - pros can sometimes kill a group that I think is alive. So I should be careful and avoid being killed. I should be skeptical of my judgement when I believe something is alive.

But it doesn't mean I'm always dead. Sometimes, a shape is just alive.

Similarly, sometimes the aji in a position is not a big deal.

I feel that this is the case in the current discussion about the stone on the left.

Sure, maybe black has a sente move around the area. But that's nothing compared to the value of the hane in the original post. White is essentially alive, and has very little to fear.

Maybe a pro can make use of something I'm not seeing on the left. Maybe not.

But I can't cower in fear just because there's a chance a pro has a different assessment than me.

I'd just play the hane. It really seems huge.

While we're at it, how strong is Crazy Stone on Android?

Bill Spight wrote:While we're at it, how strong is Crazy Stone on Android?

Something like KGS 5d, I think. Might depend on your phone's hardware.

I'd just play the hane. It really seems huge.

Oh, I'd play it, too. But this is a discussion, not a bull ring. It seems more interesting to try to tease out whether we have blind spots, to learn how other people (including pros) think, to open up new horizons, to take the scenic route. Even if you end up with the same decision, you might pick up some useful insights for future positions.

Marcel, better to not play 3. (Wastes ko threat, there is not a black double sente move there, and gives black an opportunity to realise the error of his ways and tenuki. Strangely enough the exchange of 2 for 3 seems to be slightly advantageous for black as it reduces the size of white's follow up there, in sente. Also with your continuation there is a real possibility of white aiming to use the damezumari of the big black wall in his shenanigans with f3, so you don't want to make him gain liberties by taking off the stones).

John Fairbairn wrote:

I'd just play the hane. It really seems huge.

Oh, I'd play it, too. But this is a discussion, not a bull ring. It seems more interesting to try to tease out whether we have blind spots, to learn how other people (including pros) think, to open up new horizons, to take the scenic route. Even if you end up with the same decision, you might pick up some useful insights for future positions.

Yes, I agree that it's good to consider blind spots and alternative ideas. Personally, this is a challenge for me if I don't have a particular reason to believe a particular idea.

So far, the reasons I've heard to not play the hane is that:
1.) There might be aji on the left.
2.) Pros are more wary of aji than amateurs.

So if we want to really have a discussion, let's dig deeper into this aji.

What aji is concerning on the left? Let's evaluate it.

Kirby wrote:What aji is concerning on the left? Let's evaluate it.

For simplicity's sake let's say the below to 5 happens (as white I would be tempted to play 5 at a like Marcel showed and allow the cut as the hane below 4 is so yummy). Then the obvious first aji is aiming to get the stone at 6 in sente.

Click Here To Show Diagram Code

[go]$$Wc Aji?
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 6 . . . . . . . . . . . . . . . . |
$$ | . . . , . . . 5 . , . . . . . , . . . |
$$ | . . 7 O O O . . . . . . . . . . . . . |
$$ | . . X O X X 1 . . . . . . . . . . . . |
$$ | . O O X . . 3 . . . . . . . . . . . . |
$$ | O . O X . 4 a . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , . . . . . O . . . |
$$ | . X O X X O . X . . . . . . . . . . . |
$$ | 2 O O O X . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Then the attach and crosscut could be one way to try to settle the position. The problem is black wants sente to come back and net at a but then he can't hang on to the corner.

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 0 X . . . . . , . . . . . X . . . |
$$ | . . 6 4 7 . . . . . . . . . . . . . . |
$$ | . . O 1 5 . . . . . . . . . . . . . . |
$$ | . 8 3 2 . . . . . . . . . . . . . . . |
$$ | . . 9 . a . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . . . , . . . O . , . . . . . , . . . |
$$ | . . O O O O . . . . . . . . . . . . . |
$$ | . . X O X X O . . . . . . . . . . . . |
$$ | . O O X . . O . . . . . . . . . . . . |
$$ | O . O X . X . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , . . . . . O . . . |
$$ | . X O X X O . X . . . . . . . . . . . |
$$ | X O O O X . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Another problem with the above is the first move wasn't actually sente to kill white on the left, just save the stone, so if the outside 4 stones don't have the g8 cut then white could easily ignore (and 4 might be a tesuji, black saves 5-6 exchange):

Click Here To Show Diagram Code

[go]$$Bc Aji resist
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . 7 . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . 2 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . 5 , . . . O . , . . . . . , . . . |
$$ | . 4 3 O O O . . . . . . . . . . . . . |
$$ | . 6 X O X X O . . . . . . . . . . . . |
$$ | . O O X . . O . . . . . . . . . . . . |
$$ | O . O X . X . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , . . . . . O . . . |
$$ | . X O X X O . X . . . . . . . . . . . |
$$ | X O O O X . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Not so spectacular for black. Of course this is very direct and likely premature. Better to leave it and hope to make it useful later (e.g. if black answer with one space jump on top left corner and then aims to do something on the side).

Uberdude wrote:Marcel, better to not play 3.

I agree. I did that for the analysis of local tewari, not to say that it should be played right away. Sorry for any confusion.

As I suggested above, if the aji on the left side is a concern, how about this?

Click Here To Show Diagram Code

[go]$$Wc Aji?
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . b . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . 3 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . O O O a . . . . . . . . . . . . |
$$ | . . X O X X 1 . . . . . . . . . . . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | O . O X . . . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , . . . . . O . . . |
$$ | . X O X X O . X . . . . . . . . . . . |
$$ | 2 O O O X . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

OC, leaves the cut at "a", but threatens "b".

About this variation:

Click Here To Show Diagram Code

[go]$$Wc Aji?
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 6 . . . . . . . . . . . . . . . . |
$$ | . . . , . . . 5 . , . . . . . , . . . |
$$ | . . 7 O O O . . . . . . . . . . . . . |
$$ | . . X O X X 1 . . . . . . . . . . . . |
$$ | . O O X . . 3 . . . . . . . . . . . . |
$$ | O . O X . 4 a . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , . . . . . O . . . |
$$ | . X O X X O . X . . . . . . . . . . . |
$$ | 2 O O O X . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

:W7: appears to be the proper way to defend, and feels professional. But it's gore. In a real game, I would probably kick to get sente:

Click Here To Show Diagram Code

[go]$$Wc Aji?
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 6 b c . . . . . . . . . . . . . . |
$$ | . d 7 , . . . 5 . , . . . . . , . . . |
$$ | . . . O O O . . . . . . . . . . . . . |
$$ | . . X O X X 1 . . . . . . . . . . . . |
$$ | . O O X . . 3 . . . . . . . . . . . . |
$$ | O . O X . 4 a . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | . X O X . . . . . , . . . . . O . . . |
$$ | . X O X X O . X . . . . . . . . . . . |
$$ | 2 O O O X . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

After black plays 'b' or 'c' or maybe 'd'. I'd have sente to attack the stones.

Admittedly, this feels sloppy.

But why is it bad?

Maybe kick isn't bad, it looks a plausible resistance. But it's indulgent reading if you think black would answer. It is a shape played by professionals e.g. http://ps.waltheri.net/database/game/73974/ move 20 or http://ps.waltheri.net/database/game/37399/ move 63.

Pure chance, but I am in the throes of inputting an old game and a position which shows the above dichotomy in terms that are perhaps simpler for kyu players occurred. It also has the merit of a comment by Honinbo Shusai.



White was Okunuki Chisaku, the likely Honinbo heir ahead of Jowa but he died early. He played at 7-dan strength. Black reached 6-dan (he was Suzuki Chisei who formed half of the world's first husband-and-wife pro couple). So, neither side was a slouch.

First, Chisaku had a choice between playing the White triangle stone or at the Black triangle. He chose the centre over both a base and immediate territory.

But these miai points are not miai now (an interesting idea which I've encountered before: moves can be miai at one point and not miai one move later when one has been played), although Chisei clearly thought they were. Shusai said that Black erred as it allowed White to play A. Black should now have played B, C, A.

Although Shusai did not explain why, I'm sure part of the explanation is that (as I said before) a Tennozan move is rarely bad, i.e. a stake in the centre is very important. So, here, Black has surrendered his stake in the centre, but interestingly White got absolutely no territory in this quadrant (in fact he lost 8 stones on the upper side). He got a measly few points on the right edge but the main effect was that he connected up with his peculiar carpenter's square in the lower right. This combination meant he deprived Black of any territory on the right side and snatched the tasty corner morsel from Black's lips. Although Black got the 8-stone group he struggled to make territory anywhere else, and the apparent thickness on the lower right side netted a mere ten points while White got the whole of the lower side and forced an early resignation.

I think this centre versus corners/sides issue can be visualised as a series of nested boxes, each containing a mystic message and to be opened in turn as you become stronger. The outside box tells us that the dan player realises the centre is important. The next message tells the high-dan player that the centre is even more important then the dan player thinks. The next box tells us that a pro realises the centre is even more important then the high-dan amateur thinks. The next tells us that a top pro realises the centre is even more important than the low pro thinks. The last box tells us that AlphaGo and Go Seigen both know the centre is even more important than the top pros think.

Uberdude wrote:Maybe kick isn't bad, it looks a plausible resistance. But it's indulgent reading if you think black would answer. It is a shape played by professionals e.g. http://ps.waltheri.net/database/game/73974/ move 20 or http://ps.waltheri.net/database/game/37399/ move 63.

Thanks for these examples. I actually expected a reason why the kick was bad, though I am inclined to play it.

I am ofren reluctant to play gote, but sometimes playing gote feels thick and strong (eg. after playing gote and getting a thick shape, there may be a stronger local follow up).

Since you had a different first instinct than me, I was a little curious.

Kirby wrote:

Uberdude wrote:Maybe kick isn't bad, it looks a plausible resistance. But it's indulgent reading if you think black would answer. It is a shape played by professionals e.g. http://ps.waltheri.net/database/game/73974/ move 20 or http://ps.waltheri.net/database/game/37399/ move 63.

Thanks for these examples. I actually expected a reason why the kick was bad, though I am inclined to play it.

I am ofren reluctant to play gote, but sometimes playing gote feels thick and strong (eg. after playing gote and getting a thick shape, there may be a stronger local follow up).

Since you had a different first instinct than me, I was a little curious.

A few years ago at the US go congress, a friend and I were talking to Maeda sensei, and he told us that, apart from the endgame, sente is bad. Now, granted he was addressing this to a 5d player so it shouldn't be taken entirely literally, but his reasoning was basically that sente gains nothing since it's your privilege anyways, and that gote moves are the ones that confer real gains.