Life In 19x19

joellercoaster wrote:Bill (and other players) have mentioned quite a few times the weakness of the kosumi when next to a two-stone wall. For example, the kick at leaving a weakness at R06, and the block of leaving a weakness for Black at N03.

I have a lot of trouble exploiting these, though! For example, if I (as white) were to follow up with at N03, can Black simply not eat the attack by playing at N04? Or am I being too literal-minded?

You seem to be forgetting that at move 34 there are more stones on the board than at move 30. The point of the weakness at n3 on move 30 is you have miai of coming out to the centre at n4 and connecting under at p2. By move 34 black has played the q2 and p2 connection to remove one of those miai so n3 doesn't work any more. But that's no reason to be upset, black took gote to play a fairly small move to defend against the n3 problem so you can just play something bigger yourself. In fact black can play the q2 r2 exchange and then tenuki rather than taking gote to connect, and now if you play n3 he can block at n4 and p2 doesn't connect any more as black o2 is atari, but you can capture q2 in sente to get a very strong corner so can still be happy.

joellercoaster wrote:Bill (and other players) have mentioned quite a few times the weakness of the kosumi when next to a two-stone wall. For example, the kick at leaving a weakness at R06, and the block of leaving a weakness for Black at N03.

I have a lot of trouble exploiting these, though!

I should have illustrated the weakness. The weakness at R-06 persisted for a long time. I have added some variations to my original SGF file at . Take a look.

Just the ponders of a weak player.



(I haven't read Mr Spights comment's yet, but I went to the endgame.)
Try to always think about the power of your moves.

Elom wrote:Just the ponders of a weak player.



(I haven't read Mr Spights comment's yet, but I went to the endgame.)
Try to always think about the power of your moves.

So for moves such as 21, 27 and 33, you say its slow to defend that stone. What then is the purpose of the previous move?

So for moves such as 21, 27 and 33, you say its slow to defend that stone. What then is the purpose of the previous move?

Exactly!

S2W wrote:

So for moves such as 21, 27 and 33, you say its slow to defend that stone. What then is the purpose of the previous move?

Exactly!

That said there can be some value in some cases to playing the hane but not protect the cut in order to take a big point elsewhere. If white responds by taking the lone stone it ends in gote. I think you only want to do this if white is already strong though

Sorry, but were you trying to answer my question? If so, I don't quite understand your quote. Specifically: "...but not protect the cut in order to take a big point elsewhere." I'm uncertain what this means.

I don't know why s2w feels the need to hide his reply (I don't understand why so many people use this annoying feature so often for what should otherwise be just normal replies), but I digress...

The initial hane is good. It defines the border. It (the initial hane) is mostly sente for both white or black. But the followup is gote for you (in both cases, I think).

So, you can afford to give up one stone to take sente elsewhere on the board. There are bigger plays to be had still. If your opponent takes the stone(s), the sequence ends in gote for him, and sente for you. But if you protect it now, it ends in gote for you and sente for him -- he gets the big sente elsewhere plays.

You want to try and keep control of the game by maintaining sente for as long as you can.

Don't just consider the move, or even just the next move, but think also about the move(s) after those too. Think about the followup. Who maintains control at the end of the sequence. There can be an advantage to breaking the sequence to follow it up later.

xed_over wrote:I don't know why s2w feels the need to hide his reply (I don't understand why so many people use this annoying feature so often for what should otherwise be just normal replies), but I digress...

The initial hane is good. It defines the border. It (the initial hane) is mostly sente for both white or black. But the followup is gote for you (in both cases, I think).

So, you can afford to give up one stone to take sente elsewhere on the board. There are bigger plays to be had still. If your opponent takes the stone(s), the sequence ends in gote for him, and sente for you. But if you protect it now, it ends in gote for you and sente for him -- he gets the big sente elsewhere plays.

You want to try and keep control of the game by maintaining sente for as long as you can.

Don't just consider the move, or even just the next move, but think also about the move(s) after those too. Think about the followup. Who maintains control at the end of the sequence. There can be an advantage to breaking the sequence to follow it up later.

But what is the purpose of the hane if you're just going to let your opponent have that stone if he wants it? Why not just play somewhere else to begin with and let him hane for that matter? This is actually something I've been struggling to understand lately. In my recent games (past few months), I've come to this point where I accomplish three things almost every game: I never leave any dead stones anywhere except for like a ko threat or something, I very rarely give up a single prisoner except for when I decide to abandon it far ahead of time which is seldom anyways or of course when a ko breaks out, and I always find a way to connect most if not all of my groups (I've been told to never get surrounded). These three things are almost always the case whether I win or lose, by a little or a lot, doesn't matter. At first I thought these were all good things, however, after being exposed to more higher level games and studying the styles of dan players and pros, I find that they leave dead stones all over the place and often give up over a dozen captures with without an extended ko fight. This has lead me to believe that I play to safe and conservatively and don't take enough risks. I have this bad habit of always feeling like my opponents stones are much safer than mine and that he has far more options to work with. Pretty much every game, there's a moment when I stop and think "how did he build such a great position right before my eyes?!?", however, I'll often go back after knowing the result of the game and see that his position was really no better than mine or sometimes even far worse. So back to my question, I'm trying to learn how to know when to let stones go and this particular example is what I'm talking about. Now I understand perfectly why you wouldn't want to protect that stone and would rather play tenuki. However, I can't imagine what would then be the purpose of the first move to begin with. In other words, why play a move if it's unproductive to play that moves natural follow-up?

xed_over wrote:I don't know why s2w feels the need to hide his reply (I don't understand why so many people use this annoying feature so often for what should otherwise be just normal replies), but I digress...

I do it to add emphasis and ... _{usually just before a stronger player reveals just how bad I am at the game}

That said - I'm a little curious now about your (and others) thoughts on move 19 - to me it seems that it makes a weak white group stronger in that corner and doesn't really get black that much more - in fact it seems to leave some aji behind if black plays away at 21 as white gets the chance to poke at the cut later. Why not just go for the extension straight away?

25 also seems to be settling things a little early - but it seems unlikely that white will be invaded on the left and black is weak in the corner - so ok - but even then black seems cramped afterward.

31 though ... perhaps a stronger player could weigh in on that one ... it looks like white could still live if they tenuki'd to approach the upper right with 32

Joelnelsonb wrote: Sorry, but were you trying to answer my question? If so, I don't quite understand your quote. Specifically: "...but not protect the cut in order to take a big point elsewhere." I'm uncertain what this means.

Sorry - the fault is mine for not being clearer. Say Black is next to play here:

Original position:

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X . |
$$ . . . . . . X X . . |
$$ , . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Now lets say black goes first:

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X . |
$$ . . . . . . X X 1 . |
$$ , . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

After this white gets to play elsewhere

Lets say black plays away and white goes first:

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X 3 |
$$ . . . . . . X X 1 . |
$$ , . . . . . . . 2 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Black gets to play elsewhere

Locally the difference in the two positions is not that big - 4ish points?? (exercise for me to work out later when I don't have a wriggling toddler on my lap). If there are bigger points on the board - which there almost certainly were in your case, black can afford to play elsewhere - Note that even if black's tenuchi (move elsewhere) ends in gote its likely that white will not come back anyway as this point will also be small for white. So both players should leave it until the best moves are worth +/- 4ish points in gote.

This is my poor understanding anyway. Go is hard.

Joelnelsonb wrote: But what is the purpose of the hane if you're just going to let your opponent have that stone if he wants it? Why not just play somewhere else to begin with and let him hane for that matter?
...
So back to my question, I'm trying to learn how to know when to let stones go and this particular example is what I'm talking about. Now I understand perfectly why you wouldn't want to protect that stone and would rather play tenuki. However, I can't imagine what would then be the purpose of the first move to begin with. In other words, why play a move if it's unproductive to play that moves natural follow-up?

maybe my replies aren't helping, I don't know, I replied from memory of reading the thread before. Now I re-read the thread. Maybe these aren't the best examples, and its a concept I'm learning to apply in my games lately as well, so I still may not have the best handle on it myself.

But the general concept is not only sente verses gote, but also a bit of double-sente and double-gote, I think.

If I'm reading the situation right, it comes down to who gets to play the hane first. (I'll try to stick to a general description, because I may not be totally accurate with these specific examples)

The hane is a big play to be sure, and it may be bigger, depending on who gets to take it first.

Ok, let's look at both cases:

1) He plays first. We finish the sequence locally. He keeps sente.
2) You play first. We finish the sequence locally. He gets sente.

In this case, keeping/getting sente means getting to take a really big point in another part of the board. I get behind so quickly in my games because I try to save every stone and am constantly relinquishing sente when I didn't need to. I may take what looks like a big point initially, but by the time it plays out, if it ends in gote for me, my opponent usually gets the next bigest point with his sente afterwards. Enough of those, and I quickly fall behind.

So, how can I turn a gote sequence back into sente? By sacrificing.

I play first, he responds. You need to protect, but if you do, its gote.
So leave it unfinished for now (possible sacrifice). Keep sente and take the next biggest point elsewhere. If its a play that he must respond to (else, it wouldn't be sente, would it?), then its still your turn, and you can come back to finish the gote sequence you previously left unfinished.

That means you got both big plays (no sacrifice at all).

Otherwise, if you finish the gote sequence first, then he get the other big point, and you may have lost out in the overall trade.


Also, maybe you can leave it unfinished for a little bit longer? Take a few more big plays, if there are any.

Go is a game of trading. I'll take this over here, and let you have that. You're offering a trade. See which one he takes. Hopefully your value judgement will be better than his and you'll get the bigger half.

And if he takes your sacrifice, its only one stone. And more importantly, it still ends in sente for you!!
You're opponent doesn't want to take the stone, because its gote for him! Eventually, its value becomes big enough that he will take it, so keep an eye on it (so to speak). You got to know when to hold 'em, you got to know when to fold 'em.

I think that joelnelsonb's question boils down to this.

Click Here To Show Diagram Code

[go]$$B Original position
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . O O . . |
$$ . . . . . . . X . . |
$$ , . . . . . X . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Here is a generalized position in which the moves were made.

Click Here To Show Diagram Code

[go]$$B Black hane and block
$$ . . . . . . . . . . |
$$ . . . . . . . . 2 . |
$$ . . . . . . O O 1 . |
$$ . . . . . . . X . . |
$$ , . . . . . X . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Click Here To Show Diagram Code

[go]$$W White hane and block
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . O O . . |
$$ . . . . . . . X 1 . |
$$ , . . . . . X . 2 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

IIUC, the question is when, in general, or in the specific instances in the game, is it right to make the hane and then not make the connection?

S2W wrote: Sorry - the fault is mine for not being clearer. Say Black is next to play here:

Original position:

$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X . |
$$ . . . . . . X X . . |
$$ , . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X . |
$$ . . . . . . X X . . |
$$ , . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Now lets say black goes first:

$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X . |
$$ . . . . . . X X 1 . |
$$ , . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X . |
$$ . . . . . . X X 1 . |
$$ , . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

After this white gets to play elsewhere

Lets say black plays away and white goes first:

$$W
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X 3 |
$$ . . . . . . X X 1 . |
$$ , . . . . . . . 2 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O X 3 |
$$ . . . . . . X X 1 . |
$$ , . . . . . . . 2 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Black gets to play elsewhere

Locally the difference in the two positions is not that big - 4ish points?? (exercise for me to work out later when I don't have a wriggling toddler on my lap). If there are bigger points on the board - which there almost certainly were in your case, black can afford to play elsewhere - Note that even if black's tenuchi (move elsewhere) ends in gote its likely that white will not come back anyway as this point will also be small for white. So both players should leave it until the best moves are worth +/- 4ish points in gote.

This is my poor understanding anyway. Go is hard.

Your example is not very good because the capture of the 2nd line stone is not only about endgame but also about strength and weaknesses because of the cutting points left behind and the reduction in liberties of the walls of 2 stones. But even if we extend the walls to make the cut not a worry and just focus on the endgame value, your estimate of 4 points is much too small as you should also include the sente privilege followups on the 1st line, making a below worth 14 points gote, not 4 (assuming black can't fight the difficult ko after white takes and then 1st line hanes, if he can and white avoids ko it's 12 points) .

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . O O O O O X . |
$$ . . . X X X X X a . |
$$ , . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Joelnelsonb wrote: But what is the purpose of the hane if you're just going to let your opponent have that stone if he wants it? Why not just play somewhere else to begin with and let him hane for that matter?

Sometimes it has a purpose and a good move. However sometimes (perhaps often) it is bad to make that exchange and then tenuki so it would have been better not to play the hane in the first place. However the reasons why the hane could be a mistake are rather more subtle than the big problem of being slow and taking gote where you shouldn't. So why could hane then tenuki be a mistake. The first idea is one of eyeshape, let's say black hanes as below (I've gone back to the kick shape) and then tenukis, and then white captures at some later point in gote:

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . 2 . |
$$ . . . . . . O O 1 6 |
$$ . . . . . . . X 4 . |
$$ , . . . . . X . 5 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

versus black doesn't hane and white does the gote hane connect

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . O O 4 . |
$$ . . . . . . . X 2 . |
$$ , . . . . . X . 3 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

In the first diagram white has more eyeshape so his group is stronger and more alive. Another way to think about this is if white wants eyeshape he could make the handing connection:

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . 4 . |
$$ . . . . . . O O . . |
$$ . . . . . . . X 2 5 |
$$ , . . . . . X . 3 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

Now if black wants to continue here he would obviously play atari at 5 and white could fight a ko. However it would be very silly of black to do this throw in, but this is exactly what he did, just in a different order, by playing the hane first and then tenuki:

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . 4 . |
$$ . . . . . . O O 5 6 |
$$ . . . . . . . X 2 . |
$$ , . . . . . X . 3 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

There is another subtle difference between those first two diagrams beyond white having better eyeshape: white also has better endgame. If black blocks as below white can fight a ko which is riskier for black so probably he has to pull back and lose 2 points. With the solid connection black can safely block.

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . O . |
$$ . . . . . . O O . O |
$$ . . . . . . . X O . |
$$ , . . . . . X . X 1 |
$$ . . . . . . . . 3 2 |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

If white really wanted this endgame ko and black hadn't played the hane and tenuki then white could connect like this (usually bad as it gives a peep at a). Again we can see that playing the hane first and then teunki is the same as if white played as below and then black was silly and played at b and white captured it.

Click Here To Show Diagram Code

[go]$$B
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . a . |
$$ . . . . . . O O b 4 |
$$ . . . . . . . X 2 . |
$$ , . . . . . X . 3 . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ --------------------+[/go]

However now the ko carries a greater risk for white than before because if black wins the ko it looks like this without a white stone at a as before:

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . . . . . . . . a . |
$$ . . . . . . O O 6 O |
$$ . . . . . . . X . 4 |
$$ , . . . . . X . X . |
$$ . . . . . . . . 3 2 |
$$ . . . . . . . . . . |
$$ 5 . . . . . . . . . |
$$ --------------------+[/go]

So playing the hane and then tenuki means your opponents gote move there becomes better, both in terms of eyeshape and endgame. But what if your opponent didn't want to play a gote move there but perhaps the descent and hane-connect in sente. In that case the hane and then tenuki could be a good move. This is quite an advanced endgame technique, I remember Vanessa Wong 5d, Britain's top woman, missed out on a medal at the WMSG 2012 because she failed to make such a hane in a close endgame.

Another very common reason to make the hane and then tenuki occurs in the kick shape because you want to cover the angle play weakness. So to take the game example, white can invade like this and if black blocks on top with 2 white can connect under which is nice for him to get some territory and take black's base:

Click Here To Show Diagram Code

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

Whereas if black puts in the hane and tenuki first he can capture the one stone to make some territory and eyes because 4 is now atari:

Click Here To Show Diagram Code

[go]$$W
$$ . . . . . . . . . . |
$$ , . . 2 X . O . . . |
$$ . X . 1 . X O . . . |
$$ . . . 6 4 3 X O . . |
$$ . . . . . . 5 . . . |
$$ --------------------+[/go]

As discussed before that hane did make white have more eyeshape in the corner so that's a bad aspect, but the good thing about capturing the invasion stone of 1 to keep the black group strong is a bigger plus because black's group here is weaker than white's.

This corner shape is another place where the angle play (if that's the right name) weakness behind the kick comes up. Here black's corner is surrounded by strong white groups so playing the hane of 1 and then tenuki, so that black can safely gobble up 3 is a good idea (in fact connect for 3 could also be a good idea as it's pretty big, depends how big other moves are).

Click Here To Show Diagram Code

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

Whereas here black's corner is not surrounded, but it is white's group on the lower side that is weak. So now playing hane at 1 then tenuki would be pretty dumb as white would be very happy to capture the 1 stone to make his group alive and strong. Black should not fear white invading at 3-3 here but ensure white doesn't connect to his outside group (e.g. answer at a) and then after white lives in the corner he can strongly attack the outside group (with b for example), 3-3 would be rather an overplay for white now.

Click Here To Show Diagram Code

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