What are the fundamentals?

Gotraskhalana · **#101**

Knotwilg wrote:

The examples induce a new concept: "ja choong soo" or "removing your own liberties" with the specific example of allowing "hane at the head of two". Minue even devotes an entire chapter to this concept, with lots of examples.

http://senseis.xmp.net/?HaengmaTutorial ... aChoongSoo

BTW, this part was really immediately useful for me. Despite knowing a simple example of hane at the head of two, there were several examples that would simply not have alarmed me during a game.

Cassandra · **#102**

Knotwilg wrote:

If the frequency of a certain move in a certain position tells nothing about it being right or wrong in general, then why is it played so often or rarely in pro games? The move will not always be right but it makes sense for anyone to inspect regular moves in regular positions first, before moving on to the irregular.

I believe AlphaGo is based precisely on frequency of occurrence, not as a decisive argument, but as a working argument.

Good point! Of course, frequency matters.
What else is the basis for a rule of thumb?

To give an example:
In tsume-go, I am sure that "Think twice before giving atari!" is a valid rule of thumb.
(It's not "Never start with an atari!", because there are exceptions.)

Other shape issues are by far more "regular", so these should be considered first. Only after the "regular" moves do not lead to success, the time has come for studying an "irregular" atari.

Gotraskhalana · **#103**

John Fairbairn wrote:

Absolutely. And that brings up another way of looking at "what are the fundamentals" that may be more useful in practice, even if not rigorous: candidate moves.

...

Here's an example

RobertJasiek · **#104**

Knotwilg wrote:

If the frequency of a certain move in a certain position tells nothing about it being right or wrong in general, then why is it played so often or rarely in pro games?

A certain move in a certain position is played often in pro games because it is

1) fashionable or

2) good.

Certain other moves in the position are rarely played because they are

1) unpopular,

2) good but not recognised as such or

3) bad.

Quote:

The move will not always be right but it makes sense for anyone to inspect regular moves in regular positions first, before moving on to the irregular.

I suspect you mean regular = currently frequently played in pro games.

There are different approaches to good move choice, among them:

1) First consider every conceivable move (e.g., make a Local Move Selection), filter the seemingly less interesting moves, then choose among the allegedly most interesting candidates.

2) Consider all frequent moves. Also consider some "suitable" selection of rare moves. Choose among considered moves.

Quote:

I believe AlphaGo is based precisely on frequency of occurrence, not as a decisive argument, but as a working argument.

AlphaGo's input is a tremendous sample of moves in positions. This makes it more likely that the input correlates to frequency.

AlphaGo's "thinking" might also involve decision arguments encoded in a network so that we cannot identify it as such.

AlphaGo's playing choice and output includes both frequent are rare moves. (I have not considered its rare moves as "new", but every pro commentator has.) Since AlphaGo does play rare moves, you cannot use well AlphaGo to justify that rare moves should not be considered.

***

Be careful how you measure frequency of shapes. Standard mistakes are including too many empty intersections or ignoring stones (e.g., thickness) in the farther and far positional environment. E.g., frequency does not explain a rare presence of remote great thickness.

John Fairbairn wrote:

The types of move that they both include in their list will presumably be the easiest aka the most fundamental.

Such as moves that maintain connection? Function does not equate frequencies of shapes. The function is the most fundamental - a list with a selection of only specific shapes is not.

Cassandra wrote:

What else is the basis for a rule of thumb?

Why do you care? Replace rules of thumb by principles! The basics of correct go theory are the basis of correct principles.

Knotwilg · **#105**

(Robert, I won't respond to your answer, but I appreciate it. I think it will lead us too far.)

Responding to John's exercise:

Bill Spight · **#106**

John Fairbairn wrote:

Here's an example where both higher ranked and lower ranked players can compare themselves to an even higher ranked player, a pro, in picking 5 candidate moves (and then making a final choice, of course - Black to play). I think we can all agree that this sort of position is very common and, both from that point of view and others, fundamental.

Obviously this only works if enough people here offer their list of candidates.

Incidentally, this comes from a Japanese game in which one player favoured a thick (atsui) style for a reason I had never come across before: his name was Atsushi. Calling someone "thick" over here does haven't quite the same flavour...

Edit: My response hidden out of courtesy.

Edit: Additional comment.

Cassandra · **#107**

RobertJasiek wrote:

The function is the most fundamental ...

Over 300 years ago, Inoue Dosetsu Inseki strongly recommended the study of "shape".
For those who know, everything else would shine through the stones.

skydyr · **#108**

For the exercise:

RobertJasiek · **#109**

Cassandra, OC shapes should - also - be studied.

Knotwilg · **#110**

To cover more candidates tackling"fundamentals", I'd like to suggest my own article at SL: "Basic Instinct".

http://senseis.xmp.net/?BasicInstinct

It covers 8 situations which occur very often and gives the "first candidate to inspect".

1. extend to get out of an atari
2. hane against an attachment
3. hane at the head of two stones
4. against a diagonal attachment, step up
5. block the angle play (resulting in the same position as 4)
6. connect against a peep
7. block the thrust
8. step up from a bump (less frequent situation)

I've tried to back up all "instincts" with arguments that find their root in the fundamentals of liberties, connectivity and efficiency.

Originally I had also added "extend from a crosscut" but it met with a lot of criticism as there are so many different situations that involve a crosscut, that making the extension (of the weakest stone) your first instinct would not do justice to the thought process required.

Luckily, we can find Minue's last installment, before abandoning his series, to treat the cross-cut in depth:

http://senseis.xmp.net/?HaengmaTutorial ... utPosition

Fedya · **#111**

John Fairbairn wrote:

Here's an example where both higher ranked and lower ranked players can compare themselves to an even higher ranked player, a pro, in picking 5 candidate moves (and then making a final choice, of course - Black to play). I think we can all agree that this sort of position is very common and, both from that point of view and others, fundamental.

Obviously this only works if enough people here offer their list of candidates.

Incidentally, this comes from a Japanese game in which one player favoured a thick (atsui) style for a reason I had never come across before: his name was Atsushi. Calling someone "thick" over here does haven't quite the same flavour...

I'll have a go at it:

daal · **#112**

Here's my contribution to science

Calvin Clark · **#113**

John Fairbairn wrote:

Obviously this only works if enough people here offer their list of candidates.

John Fairbairn · **#114**

Here is the answer to the Five Candidates question. I detected a couple of suspicions that there was a trick answer. There isn't, though I did have a little bit of an ulterior motive.

Here are the five candidates posited by Mimura Tomoyasu in a book on the "rules" of thickness (not one of those books in my "Slew").

I have been trying to convey recently (and have been surprised at the strong, even testy, resistance to the idea) that the word "thick" is being bandied about in a rather misinformed way here. I have already shown an example of a case where a pro said a position regarded as thick by amateurs is not really thick at all, and in fact may even be thin. Uberdude has contributed another possible example. This is another pro example.

Mimura has an amateur pupil (Mr Thickness) say, "I think this is perfect thickness" but responds by saying, "If only this were a single slab of thickness, it would be a different matter, but it has a notch in it so it's not strong to any very high degree."

In other words, it's not proper thickness and several things follow from that: it needs finishing off (and therefore there is an urgent move required here), and standard thickness proverbs such as "play away from thickness" don't really apply. In particular, once you understand this is not pukka thickness, moves elsewhere don't even have to be considered. A move on the lower side is imperative.

Actually Mimura dismissed A instantly - he only mentions it because the move appeals to amateurs. It doesn't help the thickness - it's trying to use the thickness before it really is thickness. You can't spoil the ship for a ha'porth of tar. The White move he suggests in answer to Black A is B. Black is then under attack.

Even when an amateur realises he has to finish off the thickness he will probably still be greedy and choose the territorially greediest extension C. Mimura's suggestion as White's answer to that is sartorially interesting: A. Rather than a cap he calls it a beret. First, though, he will force (click to see the extra moves).

The other wide extension is B. I'll add that and two possible two moves. This leaves a White slide to A, but Mimura says that with his thick style that's not the sort of move he fears. We can see that instead of mixing thickness and territory, Black is being consistent here in going for thickness. Consistency is usually very highly commended by pros, even to the extent of giving up a few points (at least in handicap games).

The other variation he shows is invasion by White.

Black gets thickness. Mimura says he likes this sort of shape. At first blush it may seem that this thickness also has defects and so is not proper thickness. Mimura doesn't address that question, but I have no problems with such shapes. White's invading group is taken out of the game, is subject to more thickness-making forcing moves, and the putative Black defects now are in the open centre where they can't really do any harm.

D and E are also acceptable to Mimura. In the case of E, White cannot sensibly cap as he will be attacked now that E has turned the almost-thickness into proper thickness. One reason the cap is bad is shown in the variation moves - the wall deprives White of the ladder move he tends to rely on when capping.

In the case of D, below, Black's centre-facing strategy gets a boost:

Mimura mentions that the shape on the left side is a joseki. It appears also as such in 21st Century Dictionary of Basic Joseki (Volume 1, page 219). There it is given with the move at D to finish it off, but Mimura has extended that to demonstrate E and B are acceptable, too. It seems worth mentioning that josekis are often shown with just the purely corner moves and a statement that e.g. Black takes territory and White gets thickness. In other words, it's easy to get the impression that the joseki and the thickness are finished, but in reality they are not - it's just that there's usually a range of finishing moves to consider, left as an exercise for the reader. As Yogi wisely said, "It ain't over till it's over."

The fundamental point, it seems to me, is that unless you learn to define thickness properly, you can't get into the rather simple, but boy how powerful, way of thinking that Mimura illustrates here.

Gotraskhalana · **#115**

I find this discussion very interesting, especially, as I don't even have the thickness definition problem, but have explicitly instructed not to play so close to my "wall".

But does anyone want to comment why E10 clearly does not need to be considered at all? I think that it is a big issue at my level to know when a contact interaction is over.

skydyr · **#116**

Gotraskhalana wrote:

I find this discussion very interesting, especially, as I don't even have the thickness definition problem, but have explicitly instructed not to play so close to my "wall".

But does anyone want to comment why E10 clearly does not need to be considered at all? I think that it is a big issue at my level to know when a contact interaction is over.

The problem with E10 is that it doesn't affect white's group on the left, so white will immediately respond with a move on the bottom to cramp the area that E10 sought to expand black's control over.

RobertJasiek · **#117**

John Fairbairn's joseki example:

Thickness is connection, life and potential for making territory. Before an extension, the wall is connected and alive but connection is only 0-connection (Black cannot answer a white peep by a remote tenuki and remain connected), life is weak because, if attacked, the wall must run and the potential for making territory is weak because, if attacked, the wall loses much of its potential for making territory. Therefore, without extension, the wall lacks stability: there is a great difference of the wall's potential between Black starting and reinforcing with an extension versus White starting and attacking with a checking extension. Black's extension is required to provide eyespace for the wall, stabilise its connection, stabilise its life and stabilise its potential for making territory. Only an extension develops the wall's full local potential for making territory.

AlphaGo might sometimes disagree because of having a more global perception of potential for making territory. It might be happy with the weakest form of thickness of being connected and alive at all. E.g., L11 would be an indirect extension transporting influence from the wall to a global distribution and preparing a fight if White tries to profit by attacking the wall.

Bill Spight · **#118**

skydyr wrote:

Gotraskhalana wrote:

I find this discussion very interesting, especially, as I don't even have the thickness definition problem, but have explicitly instructed not to play so close to my "wall".

But does anyone want to comment why E10 clearly does not need to be considered at all? I think that it is a big issue at my level to know when a contact interaction is over.

The problem with E10 is that it doesn't affect white's group on the left, so white will immediately respond with a move on the bottom to cramp the area that E10 sought to expand black's control over.

And, if White were to play at E-10, it would hardly affect Black's group. In addition, it has no potential for development in the top left quadrant, because of the presence of Black stone in the top left corner.

I think that SDKs shoud consider it, and quickly reject it. If a DDK made the move I would commend them for having thought of it.

Bill Spight · **#119**

RobertJasiek wrote:

AlphaGo might sometimes disagree because of having a more global perception of potential for making territory. It might be happy with the weakest form of thickness of being connected and alive at all. E.g., L11 would be an indirect extension transporting influence from the wall to a global distribution and preparing a fight if White tries to profit by attacking the wall.

Interesting that you mention L-11. That is also a play that is worth considering, IMO.

It may be optimal play, and AlphaGo's choice, offering the best winning chances against quasi-random play. But against a strong human opponent, I think that K-04 may well offer the best winning chances.

Uberdude · **#120**

A little late to the party, but here is my thinking on the position before I saw John's answers.

First instinct is k3, the/a standard joseki move. Black's wall doesn't have eyeshape and has the f4 peep so should extend to make a base. There might be fancier slightly better moves, but this can't be bad. Next thought is noticing black got the d8 push and white obbediently extended rather than resisting with the hane or turn on lower side (black's top left corner stone makes the latter less appealing). I've heard differing opinions on this push from strong players, but if white only extends then I think black can be slightly happy. So it's interesting to see that shape appear in this book. In fact that extra push might mean he can extend a bit further.

But John was talking about thickness so then I consider d9 pushing again. e10 would be a knight's move to get ahead, but it's not thick (has a cutting point and no pwerful followup as didn't take a white liberty) so white would easily tenuki it to play around k3 and reduce the power of the wall. But d8 he will probably answer with hane and maybe black can connect to the 4-4 with a huge wall if white just keeps on extending as below. White gets a big territory, black gets a big wall, I think we can tick the "thick style" for this way (but even so black's wall still has some cuts/peeps so it's not super-duper thick and white can use these in his operations). I'm not sure yet who this result is good for, but if it's black then white could consider 4 as double hane, 6 as hane, 8 as hane, or it might also be good to tenuki at some point when black's followup isn't too severe and wedge the top side (e.g. for 12).

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

Click Here To Show Diagram Code: [go]$$Bm11 $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 8 . . . . . . . . . . . . . . . . | $$ | . 9 5 6 . . . . . . . . . . . . . . . | $$ | . 0 4 X 7 . . . . , . . . . . , X . . | $$ | . . . 2 3 . . . . . . . . . . . . . . | $$ | . . . O 1 . . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . , . . . . . , . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O O X . . . . . , . . . . . O . . . | $$ | . . X O X . . . . . . . . . . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Click Here To Show Diagram Code: [go]$$Bm21 $$ +---------------------------------------+ $$ | . . . 6 . . . . . . . . . . . . . . . | $$ | . . O 1 4 5 . . . . . . . . . . . . . | $$ | . X X O 2 3 . . . . . . . . . . . . . | $$ | . O O X X . . . . , . . . . . , X . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . . . . . . . . . . . | $$ | . . . O X . . . . , . . . . . , . . . | $$ | . . O X . . . . . . . . . . . 7 . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O O X . . . . . , . . . . . O . . . | $$ | . . X O X . . . . . . . . . . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Next strategic choice is to approach the lower right corner, but this is probably an overplay. If white answers with the knight's move then black is happy to have got this exchange in sente and then extend on the lower side on the 4th line without worrying about white's 3rd line checking extension:

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . 2 . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O O X . . . . . , 3 . . . . O . . . | $$ | . . X O X . . . a . . . . 1 . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

If L4 as above then you need to see what happens if white later does the standard invasion point of a, the f4 peep should help (if this fails then a gentler reduction such as a one point jump above, or even higher given d8, might be proper).

Click Here To Show Diagram Code: [go]$$Wm4 (maybe 9 can resist) $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . 7 . . . . . . . . . . . | $$ | . O X X . . . . . 4 . . . . . . O . . | $$ | . . O X . . . . 3 . . . . . . . . . . | $$ | . O O X 6 5 . . . , X . . . . O . . . | $$ | . . X O X . . . 1 2 . . . X . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Looks to me like white is getting out and making shape rather nicely here, and the black wall is even feeling a little vulnerable. Maybe black should cap? If white slides then a is simple, but maybe black can go fancy like b? Although the cap is less common against this invasion and feels a bit like you are being inefficient with the wall, as the wall is not actually so strong my first feeling is this might be the better direction. I expect a Korean player would be happy to make the small life inside though (and then he'd probably kill my wall later anyway ;-)

).

Click Here To Show Diagram Code: [go]$$Wm4 $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . O . . | $$ | . . O X . . . . 2 . . . . . . b . . . | $$ | . O O X . . . . . , X . . . . O . . . | $$ | . . X O X . . . 1 . . a . X . . . . . | $$ | . . O O X . . . . . 3 . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Black could also extend to k4. Now I might expect an invasion at a later, or of course gentle reductions from the outside like b if white later builds the right side.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . 2 . . | $$ | . . O X . . . . . . . . b . . . . . . | $$ | . O O X . . . . . 3 . . . . . O . . . | $$ | . . X O X . . . . . . a . 1 . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

But these are all happy dreams, white should probably pincer. Not sure which one, maybe 2 space high or 3 space low (which aims at making 2 space extension base to a and then peeping to both make own eyespace and take the wall's with b-d:

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . d . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O O X c b . . . , 2 . . . . O . . . | $$ | . . X O X . a . . 2 . . . 1 . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

If they follow the old joseki below probably white is happy as black is low and there's still ways to use the pincer stone (e.g. a-c combo, but could be somewhat heavy) though I do worry about it being gobbled up whole.

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . 4 . . . | $$ | . . O X . . . . . . . . . 3 . . . . . | $$ | . O O X . . . . . , 2 . a b . O . . . | $$ | . . X O X . . . . . . . . 1 . . 6 . . | $$ | . . O O X . . . . . 7 c . . . 5 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

So maybe white emphasises the lower side with this slightly trick joseki (don't forget to push at 11 before 13).

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

Click Here To Show Diagram Code: [go]$$Bm11 $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . O . . . | $$ | . . O X . . . . . . . . . X . . 2 . . | $$ | . O O X . . . . . , O . O X . O 1 . . | $$ | . . X O X . . 4 . . . . . X . . X . . | $$ | . . O O X . . . . . . . O O 3 X . a . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Black has miai to attack whichever side white doesn't defend (I think white chooses the lower side here as it also takes the base of the wall) but as black has the top right attacking on the right is nice for him. There is some fun aji in the corner around the cut with a which Andrew Kay is rather fond of.

Or does black go for counter pincer? It feels rather overconcentrated and white's group can get out easily enough and black's approach group is weak too.

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

Another strategic choice would be tenuki, leave the wall to fend for itself. It feels bad, but maybe there is some merit in a fast-paced opening:

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , 1 . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . 5 . . . | $$ | . . W . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . 3 . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O O X . . . . . , . . . 4 . O . . . | $$ | . . X O X . . . . 2 . . . . . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

Like this black builds a nice moyo around the top and right sides, and says "go on! do your worst" with the wall. But if you are going to play like this why make a heavy wall and give your opponent a bunch of solid territory there in the first place? It would be better to leave that area less played. Also white's marked stone poking out reduces black's potential on the top left area. It does remind me a bit of Go Seigen dangling those stones for Kitani though...

So how about other extensions on the lower side? Seeing as black got d8 maybe go one further? And high has a nice feel to it: as it's wider there is more chance of an invasion later so don't try to make territory. White's checking extension of 2 is natural, or else black gets to approach the corner and come down from the 4th to 3rd line and get that overindulgent dream result from when he approach first. White now threatens to invade at a, that shape I posted about previously in the thread. Seeing as the wall is not alive yet such an invasion looks quite a headache for black, so he could pre-emptively play one of the moves against it: the territorial b or influential c. The latter is more consistent, but it feels a little slow as there is not a clear follow-up as white 2 is close to the 4-4. So maybe black could tenuki to the top or right side, but it feels a bit cheeky (though not as much as immediate tenuki).

Click Here To Show Diagram Code: [go]$$B $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . c . . . . . . . | $$ | . O O X . . . . a , 1 . . . . O . . . | $$ | . . X O X . . . . . . . 2 . . . . . . | $$ | . . O O X . . . . . b . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

If black 1 was one to the left then the cap has a follow-up (a) white would defend against with 4 (or high) and then maybe black could more reasonably tenuki:

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

So after all that I need to pick 5. Here they are in order of preference. a and b I both like. c is a lot easier to play against weaker players I can bully. d is really only there because we are talking about thickness, I wouldn't have the confidence to play such an extravagant wall-building style unless I was drunk!

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , e . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . O d . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O X X . . . . . . . . . . . . . . . | $$ | . . O X . . . . . . . . . . . . . . . | $$ | . O O X . . . . . , b . . . . O . . . | $$ | . . X O X . . . . a . . . c . . . . . | $$ | . . O O X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

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