Hi,
I'm currently playing a game on DGS trying to think through my moves. Reaching the end of the fuseki. I got to the below position (playing White), I really wasn't sure what to play (for information, I already made my move). I'd be glad to have the point of view of stronger players on this situation.
See below a few spot I wondered about playing? Am I missing any other which would make more sense? Which would you select and why?

Thanks,

Click Here To Show Diagram Code

[go]$$c Where would you play as White in this position?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . O . . X . . X . O . O O . . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O X X X . . |
$$ | . . . . . . . . . . . . O . O X O . . |
$$ | . . a O . b . . . , . . . O O O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . c . . . . . . . . e . . . . |
$$ | . . O O . X . . X , . . . . . , X . . |
$$ | . . O X X . . . . . d . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Two others to consider are O4 (better than P5) and C15.

Given that there is no single move to secure white's moyo on the left I think I would be inclined to reduce with O4 and wait to see how black tackles the left. Whatever black does should allow white to secure enough.

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Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

Thank you for your response.
That's interesting. I tend not to know when to shoulder hit (or not) and didn't even consider it.
I would have thought it would give a lot to Black and I would be afraid not to get a proper payback from the territory he would be able to make.
I believe you say it is better than P5 because it does a better job at flattening white, am I correct in stating that?

Click Here To Show Diagram Code

[go]$$c Where would you play as White in this position?
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . O . . X . . X . O . O O . . |
$$ | . . . O . . . . . , . f . . X X X . . |
$$ | . . b . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O X X X . . |
$$ | . . . . . . . . . . . . O . O X O . . |
$$ | . . a O . . . . . , . . . O O O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . e . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . c . . . . . . . . . . . . . |
$$ | . . O O . X . . X , . . . . . , X . . |
$$ | . . O X X . . . . . d . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

I was surprised to learn that White is to move - I'd expected Black sente.

Black is overconcentrated at the right side, White is thick. The left side is wide, the lower side is relatively big but it is contained by the White thickness. As such, the invasion at D doesn't seem urgent. There's a cutting point at the top (F) but it's not very interesting as Black's top right is not vulnerable.

Looking at the left side again, it is so wide that it is even overstretched. Territorial moves like A or B come to mind, but they don't solve the main problem, which is the potential separation of the lower left.

Leaning at C is active but Black may simply ignore and invade, as he's behind.

Therefore, I advocate a calm move like E. Next, B and D are miai for White.
(still looking at C though)

Me too I have a hard time to decide how to develop the left but O4 is still too close to White's thickness I think. If you decide to play the bottom I'd invade.

I like 'd'.

_________________
be immersed

I find this interesting because where you see thickness I see a potential weak or heavy group.

As objective reasons for calling it potentially weak, it does not have any guaranteed eyes at all yet and is bounded by strong Black groups on both sides. If Black plays a move against it, White probably has to defend (or else accept a truly weak group), but his defensive move would be purely that - there is no move to make territory while defending.

I am also influenced in my opinion by a growing realisation that pros see weak groups much earlier than I do. To some extent that must be because they have far more terrifying weapons than I do, and so can go after lions where I can only go after rabbits, but I think also a big part of the reason is that we amateurs tend to think of weak groups as anaemic, weedy clusters that have to live urgently, whereas pros seem to count many groups that allow a powerful forcing move (as is the case here) as weak.

In this particular case, I would also argue that the White group cannot really be regarded as thick because it has no potential to do what thickness normally allows you to do. Black has no weak groups roundabout yet, and White can't even surround any territory with it. There is possible influence in the centre but it is too nebulous and too easy for Black to circumvent.

If you accept that thinking, an invasion at 'd' looks horrendous: it would lead to a splitting attack on two White groups. In that light a shoulder-hit reduction at O4 on the lower side looks more promising. If the reducing group can link up with the White group above it could give him some proper centre thickness. But that seems speculative, and seems to hand the initiative over to Black too readily.

So the right side (and maybe a quiet move there) seems more worthy of attention. This is still fairly open and so can be seen as a virtual territory of three units. Normally the idea is that out of two units of virtual territory, you can expect to get one (the opponent doesn't get much of the other but at least destroys it). With three units it much more problematical to come up with a good plan. The shimari at C15 looks good in that it takes one third of the virtual area at once and reduces what is left to two units. But that means White is looking at not much more than 40 points there and less than 10 in the upper right, with no immediate prospects of more anywhere else (all because of the inefficient White group on the right). Of course he gets the komi as well. Black's lower side can be treated as a three-unit virtual territory where he gets two thirds, so all in all he will at least match White's territory. But has the potential to make some more on the right, and his lower side currently looks easier to grow than White's left side.

On that basis, it seems to me White has to up the stakes, and so a quiet move like C15 or C10 could verge on being a slack move. I too would be looking at F5. It increases the potential value of the left side, overconcentrates Black and heightens the value of a subsequent reducing move. It also extends a helping hand to the right-side White group and has a good follow up around F10. The problem with C15 is that it can too easily turn into gote, so I'd be looking for tesujis to turn this into sente, but even if they don't exist, I think F5 may be enough to keep White in the game. At the very least it's liable to make Black enter the left side at once, and depending on how that goes White might get enough thickness there to exploit Black's potential weakness around M16.

Seems thick to me, but this is more of a feeling than something I can logically articulate.

Either way, I feel comfortable as white in this position, so several options probably work.

_________________
be immersed

I had something like this in mind.

Click Here To Show Diagram Code

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

White has given the lower side to black but has not lost the move at F5. The stones just played work with the group above to make potential territory. Those stones above were sort of meaningless wedged between two strong black positions. And the left side is untouched. White still has sente and so all the options on the left remain. As I said in the first post, the left is too big to finish in one move so now a move at 'a' looks plausible.

_________________
Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

I like DrStraw's final position. Seems reasonable.

It doesn't seem proper for black, but what is white's plan if black resists at ? I suppose the bottom left could be pressured without the direct connection, but I don't see how, exactly.

Click Here To Show Diagram Code

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

_________________
be immersed

The White group on the right side has a half eye in the middle, a strongly connected chain with 7 liberties to it, and can make an eye at the side. If that's not thick, I need to reconsider what thickness is. I agree that if Black adds many moves, then it can become weak.

Looking at Straw's sequence, I agree this doesn't overlap as much in influence as I thought and maintains White's overall thickness while keeping sente too. It's hard to see how White can resist. Added to the difficulty of finding 'the' move at the left side, I tend to agree now.

I also agree the invasion at 'd' in the first diagram would have been greedy.

If White can pull this off in sente, then build the left, I fully agree. As Black though, I would look for any opportunity to tenuki and play on the left side. in your diagram already seems like good timing, as it is an almost pure territory move.

In any case, Black is behind and this is largely due to having made the exchange at the top right, where Black became overconcentrated and White ... thick.

Good question. I did think of that when making the diagram but did not follow through on it because I was just posting quickly. Now I see it on the board my first reaction was to play 'a' and see how black replies.

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Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

But it's not a half eye, is it? White needs two moves to guarantee an eye there.

I too have a hard time not seeing the group as thick, but let me try and imagine the case: this group has a lot of ways to live, but it's still prone to being bullied. No one would look at this board and say they'd be happy to scrounge for an eye on the right side, or spending two otherwise meaningless moves making that center eye an actual eye.

_________________
Occupy Babel!

That's the general argument against allowing a weak group, but here, I'd feel comfortable giving black like 3 free moves in the area. I'll gladly play a Malkovich game from this position with anyone that disagrees

Any group that's not 100% alive can potentially be attacked, but black doesn't have much to gain right now by attacking, IMO.

That's why I'm even comfortable invading at 'd' here, even if it's greedy. Black could totally surround the invading group and I'm still not afraid of dying. At that point, sure, black can get some free attacking moves, but what good are they? Where are black's points?

That being said, I think DrStraws calm shoulder hit is a simpler way to wrap up the game and win, so I like it better.

To have a meaningful discussion, we need an even game to evaluate. From this board position, there are many ways to victory, so most options work.

_________________
be immersed

Interesting observation. I thought this game was fairly even and I would be comfortable taking over either side. If it were blacks move I would say he was definitely ahead.

_________________
Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

Now that lots of people have weighed in, I gave the position to Crazy Stone for fun (2 million playouts). Its top choices are listed in alphabetical order (that is, it thinks a is best), but all four are very close in evaluation. It assesses the current position as approximately W+5.5 (assuming 7.5 komi).

Click Here To Show Diagram Code

[go]$$c White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . O . . X . . X . O . O O . . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O X X X . . |
$$ | . . . . . . . . . . . . O . O X O . . |
$$ | . . . O . . . . . , . . . O O O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . c . . . . . . . . . . . . . |
$$ | . . O O . X . . X , . . . a . , X d . |
$$ | . . O X X . . . . . b . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Thank you.

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Still officially AGA 5d but I play so irregularly these days that I am probably only 3d or 4d over the board (but hopefully still 5d in terms of knowledge, theory and the ability to contribute).

Thank you so much for all those detailed and valuable answers ! Very enlightening!

I'm amazed by how great is this online go community...

P.S. I ended up playing the slack move of C10 (iron pillar) and my opponent invaded at D14 as a result.

As I didn't see anyone make clear the o4 vs p5 difference: p5 is typically used against a shimari that has 2 distant extensions, the idea being you have miai of attaching on whichever side of the shimari black doesn't defend. However here black only has 1 extension which is close, so for sure he would defend the lower side. But then white doesn't have anything particularly good against the r7 stone, for example black can connect up and white didn't achieve much below. As you say the o4 shoulder hit actually flattens black more, pushing him down to 3rd rather than 4th line.

Click Here To Show Diagram Code

[go]$$Wc Cap inappropriate
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . . . O . . X . . X . O . O O . . |
$$ | . . . O . . . . . , . . . . X X X . . |
$$ | . . . . . . . . . . . . X . . . . . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O X X X . . |
$$ | . . . . . . . . . . . . O . O X O . . |
$$ | . . . O . . . . . , . . . O O O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 1 . 3 4 . |
$$ | . . O O . X . . X , . . . 2 . 5 X . . |
$$ | . . O X X . . . . . . . . . X . 6 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

FWIW o4 and c15 were my 2 main thoughts in that position. And regarding John's thoughts that the right side white group is not thick but potentially weak, I would call it thick as it's a big solid chain with no peeps/cuts/other weaknesses (but with little interest in extended discussions of Japanese terms) but also be mindful that in the future it could be attacked as a whole so o4 has a tinge of prophylaxis, extending a helping hand to the white right side group before the stakes are raised (at this point black is unlikely to want to take a big loss on the lower side for some speculative attack of doubtful profit on the white group, but maybe later he would).

I'm intrigued by the view that White's right-side detached iceberg is thick, and especially by the supporting view that it is a solid chain with no reference to its usefulness.

Of course there is always scope for interpretation, but I think "thick" here is being mixed up with "safe" - is this a Jasiek definition?

And I don't think that even "safe" here is an acceptable view. The group as it stands has no guaranteed eye either in the centre or on the side, and is exposed to profitable and strengthening Black ijime (bullying) moves on both side skirts and probably in the centre. That looks like at least 5 or so free points for Black.

To repeat: what's the point of a "thick" group if it can't do the work of any thickness? What's its point if it gives the opponent good, free moves?

It's already been accepted that the White shoulder hit provides some succour for the iceberg above, but how can a group be called thick if it needs help?

A prime requirement for thickness is that it should be a tower of strength, not just a tower. It has to be efficient. Thickness is as thickness does. If it ends up being attacked itself, tant pis, and just avoiding attack doesn't make it thick.

Below is a position from a Japanese book under the heading "Looks thick but is really thin."



This large White group at least really does have a guaranteed eye, and it even has an extension. Yet the text describes it as "unexpectedly thin". It adds that "to an amateur's eyes it appears extremely thick, but Black has two forcing moves at A and B and White does not really have two eyes yet. Despite appearances, the group is actually thin."

One reason pros don't have to count so much to see who is ahead is that they can see inefficiencies like this at a glance and so know who must be behind. Of course, I may be wrong in that this group, like any iceberg may hide 8/9ths of its value below the surface, but it looks to me like enough go-board warming has already taken place.