In what books (and chapter) can the rule for the ideal distance from a wall be found and, ideally, discussed? I only recall seeing it in a less known book, but it is used in many other books, so this is an important rule, and I would like to learn more about it.

The distance of an extension from a wall and related aspects (when to make or not to make an extension, where to play a checking extension) are discussed with powerful principles in Joseki 1 - Fundamentals, chapter 12.3 (p. 233 - 244). In particular, the principle for the distances of extensions from walls is much better than what you can find in other books, where it is typically the weak and sometimes wrong proverb "n+1 lines from a wall of n stones".

Thanks. If you also know of books you did not write that contain information about this, I am interested too, even if they are less good in your eyes.

I am asking this question because I vastly prefer buying books from SmartGo Books, thanks to their interactive diagrams.

I have looked through the list of SmartGo books and cannot recommend any for the thread subject's question. I cannot recommend any other book for this purpose.

You might read about related topics (connection, haengma, efficiency, reading) without getting a direct answer to your question. For this purpose, among the SmartGo books, Fundamentals Principles comes close. Other, non-SmartGo books come closer. Concerning books by only other authors, read everything about haengma, or study joseki dictionaries and hope to get your enlightening faster than within years (I needed 2 years of autodidactic study for this purpose).

I.e., if you avoid classical books and particular authors, your study is as inefficient as your extensions from a wall;)

I don't think there is such a rule in oriental go, mainly because the concept of a wall is more of a western one. Although the word for wall (heki) occasionally crops up in Japanese texts, for example, it is much, much less common than in western talk, and you will not normally find it in books of technical terms. Beyond the utter beginner level it is very rare. The reason is that Japanese will refer instead to thickness or influence, neither of which may actually look like a wall. The Japanese also have the advantage of being able to distinguish easily between thickness and influence, and between the two kinds of thickness (atsumi and atsusa). Their go is accordingly more refined.

It behoves western players to learn to stop trying to create walls. If you try to create thickness instead you will find you are more efficient. You are then essentially creating buildings (or fortresses) instead of just walls. It's useful to remember Laozi's point that what makes a wall useful is the holes in it (for doors and windows).

Since a wall is not a usual concept in Japanese and thickness is by its nature a chaotic shape, the idea of a computable extension does not really arise.

Another point is that it is bad go to extend from a position simply to try to map out territory. There are bigger imperatives such as making a base, checking the opponent's expansion or making pincers, all of which affect the size of an extension profoundly.

The notion of simply surrounding territory does exist, and is called kakoi in Japanese, but it is rather advanced and has not been dealt with properly anywhere in English AFAIK (or even in Japanese in book form, but it's mentioned mostly in advanced game commentaries). It does not really involve walls (it's based on jimoyo - a kind of moyo).

What you are referring to as the proverb is more of a tactical idea which goes back to the ancient Chinese book Xuanxuan Qijing, so it's already at least about 1,000 years old. There the advice is to "if you stand on two, extend three" and "if you stand on three, extend four". "Stand" here is a technical term for a nobi move that extends towards the centre from a stone or stones anchored on the third line. This creates only a mini-wall. Also, rather than an ideal extension it is usually taken as a reference to an upper limit for the extension. There is also the point that in ancient Chinese go it was important to keep your stones well connected because of group tax.

Within its limitations this ancient proverb has proved its usefulness also in strategic situations, too, and the most accessible version is in Takagawa's Vital Points of Go (Chapter 1). This is a classic text for western players and still I think available (either because of a reprint or because someone in the US found a crate of old stock - I forget the details). The English is a little dated and maybe confusing ("stand" is made to be "stop" here, and "confrontation" is used for miai, and so on), but it's a gold mine for go theory in general.

I presume you are right that the n+1 command (or weaker forms of it for only special cases) is unpopular in Asia, however, it occurs in some English translations of Asian books nevertheless (I forgot which).

Two kinds of thickness do not show a more, but show a less, refined Asian go understanding of thickness itself. (Compare Joseki 2 Strategy.) 'Using thickness' is a different topic, which has not been covered in great detail in English texts yet; so probably Asian texts would still be more detailed.

The Vital Points of Go does not qualify as a gold mine, even ignoring the dry writing style. Its best part is about tewari but explains too few of its aspects (Compare the aforementioned book again.) If somebody accidentally gets the book, it is worth reading quickly, but the book is not interesting enough for the trouble of trying to buy it.

This is very interesting, thanks.

So, it seems hard to find references to this "n+1 spaces from n-stone wall" proverb. I was looking for such references because, if my memory serves well, Yilun Yang justifies some extensions by writing that they are "ideal", and it often seems that it is only because they follow the proverb, so I got curious about it.

Anyway, it is reassuring to see that it is at best a rough guide, so that there is not so much theory to learn about it, hopefully.

Standard counter-example to the "proverb":

Click Here To Show Diagram Code

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

This is the correct extension (if on the 3rd line). Instead, White a is refuted by Black b, threatening the connection.

This invokes an interesting topic that applies in martial arts, zen and probably many other eastern things that become popular in the west. Do some oriental teachers tailor their teaching to the western audience?

I think the answer is unequivocally yes, but will leave aside whether this is a good or bad thing (though it's certainly commercially astute).

I think the best known example is Zheng Manqing (Cheng Man-ching) in taiji. He is on record as treating his oriental and western students quite differently, and being "amused" by the attitudes of his western students. But it is his "western" style that he has become famous for. I was talking recently to a female Chinese martial arts grandmaster and she said people in China were very scathing about this style of taiji. They call it "noodle taiji" because he goes all super-floppy, a style which obviously appealed to the hippies and others of the 1960s counterculture who were more interested in getting in touch with their feelings than with getting embroiled with a live opponent. I have also seen called Zheng's style referred to as tofu taiji for the same reason.

I think we see the same process of adaptation by popularisation with the zen and tao writings of Alan Watts, although he personally has a sound basis. The most egregious case are books like "The Tao to the Executive Loo" or the "Book of Changes for Brothel-keepers" which may be popular with a western audience but are a travesty of the oriental originals, and seem written by people whose nearest contact with China is the local takeaway.

I have not read much, if anything, by Yang Yilun but I know he's popular with American students. Perhaps they can tell us: is there any sense in which he may be tailoring to a western audience? And if so, is that a good thing?

The first volume of Improve your Intuition has a section on how far to extends. There's a general rule to make a three space extension from two stones, and a four space from three stones, but there are exceptions, like the one Robert gave, and it's doubtful whether it generalize to a n-n+1 rule. Apart from that, the strength of the position you're extending toward is important. If on the opposite corner is a lone 4-4 enemy stone, you can extend further than if there was a shimari, and if there's a shimari, you can extend further than if there was a very strong position due to whatever joseki was played in that corner.

Oh, dear. Somebody forgot to tell Shusaku, Shuho, Shusai and a host of 9-dans.

Nice extreme example from Iwamoto vs Fujita:

Let me fix your all-too-certain words:

This more modest extension of only 3 spaces from a 3 stone wall, rather than the 4 spaces you might expect, is usually the best response. That's because extending further makes black b, which is a big point both players would like to get in the future, almost sente as it threatens an invasion to separate the wall from the extension, and if white answers it is rather sad to give black such an important point in sente rather than gote. Of course it is possible to extend further if you have a good plan to deal with that knight's move.

John's example provides one such global position, white answers the knight's move on the top side which is a double purpose play extending from his top right approach and reducing the potential the knight's move developed.

In the Iwamoto vs. Fujita game, C10 remains a mistake, although the left side follow-up to G14 can be delayed due to global considerations of first playing in more valuable regions. After White 14, C10 at C11 would be a better placement because a) C11 connects the three white stones and b) C11 fulfils essentially the same purpose as C10 towards the lower left side and corner. The major difference of C10 is that it gives Black to option to invade above and makes it necessary for White to reinforce the gap above if the string of three white stones shall develop its full potential. Black P3 played in the lower left corner, e.g. at C4, would exhibit the weakness in White's shape more clearly. As much as White should reinforce, he cannot do so because of then creating overconcentration of almost having played one stone too many on the left side. The example game proves that Kageyama was not the only "amateurish professional";)

From memory: I remember him using in cases where a line closer would mean you didn't have a base and a line further meant you were too thin and open to invasion and your opponent could attack profitably here if given the chance. There may be more advanced/nuanced examples that I'm forgetting.

I'm guessing Workshop Lectures is your best bet, but I haven't gone through them.

Among the first go books I ever bought was a set of small books about the basics, published by the Nihon Kiin. One of them provided an extensive discussion of the proverb in question. As John Fairbairn indicates, it is not about walls in general, but about standing walls of stones connected linearly with the bottom stone on the third line. The main point of the discussion was that, unless the opponent had stones in the vicinity, an invasion of those walls plus the indicated extension was not a good idea. Generally the invasion could be killed. I have not seen any other book that went into such detail, and those little books are long out of print.

Pro games show frequent violations of the proverb, usually by making closer extensions, particularly in the presence of opposing stones, and sometimes by making wider extensions, or no extension at all. (Walls with eye shape do not require an extension, and the proverb does not apply to them, but sometimes even linear walls do not get an immediate extension.)

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

Visualize whirled peas.

Everything with love. Stay safe.

Except when restricting one's view artificially like allegedly for the proverb, there is no need to avoid consideration of walls of any shape (needing an extension for eyespace at all).

Another example of an amateurish professional, this time Honinbo Shusai:



In 270 examples of this three-stone wall opening, White extends with a three-space gap only about 90 times, so it is the commonest single choice but nowhere near a majority choice. Which means, I suppose, most pros are amateurs... (or worse: "Japanese 9-dans").

Also, the three-space choice actually has by far the worst winning ratio (about 42%). The best is the knight's move into the centre (60%).

Tenuki is very common, and this opening, with or without tenuki, illustrates some very interesting aspects of go strategy that normal joseki evaluation criteria completely miss. One is that this wall-based group is not just resilient when attacked, but usually manages to stave off the opponent's attack without incurring any significant collateral damage. There is a class of josekis to which this applies, the most notable examples being when a low approach to a komoku is attacked with a widish pincer and the pincee then jumps out to the fifth line above the pincer. It seems that it is the angle of egress into the centre that counts for much.

The other strategic aspect of this three-stone wall is that it conveniently fits into a well known sacrifice strategy where it can be sacrificed because the opponent will have to use far more than three stones to capture it. This no doubt is why it is often treated with tenuki. In general straight walls of stones are often considered for sacrifices because they are, in one sense, inefficient in that they can be difficult to turn into true thickness.

This opening is still being played and so merits some study. Even by professionalish amateurs.

:)

Such reminds me of my 9-7 openings when I play forcing moves against corners and then tenuki. Such strategies have been becoming more popular also among European 4d+ for the last two years. Single stone forcing moves were played also by others.

However, your professional examples differ: the forcing moves install a heavy group while we European amateurs prefer light groups (typically only 1 or 2 stones). A heavy group cannot be easily discarded permanently by tenuki. Therefore, we see some soon extension in the pro examples you have shown thus far.

Again, I am not convinced by White's strategy (C10 at C11 is at a better place). Do we see such examples as intentional hamete in no-komi games, which hope for Black's suboptimal exploitation of the aji?

Kombilo search among 70179 GoGod games, ignoring 2 unfinished games. Pattern without fixed colour:

Click Here To Show Diagram Code

[go]$$W
$$ ----------------
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . . X . . .
$$ | . . X X . X . .
$$ | . . O O O . . .
$$ | . . . . . . X .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . . . . . . .
$$ | . . O , . . . .
$$ | . . . . . . . .[/go]

1807-08-22a: Nagasaka Inosuke - Kadono Matsunosuke (B), 143g
1914-06-08a: Nagahama Hikohachi - Kogishi Soji (B), 33a
1917-12-12: Fujita Toyojiro - Iwamoto Kaoru (B), 11b
1925-04-00b: Honinbo Shusai - Segoe Kensaku (B), 17b
1928-00-00a: Go Seigen - Wang Youchen (W), 42f-
1929-11-07b: Takahashi Shigeyuki - Hashimoto Utaro (B), 15c
1991-12-06a: Kim Heui-chung - Kim In (B), 14d-
1993-12-28b: Yang Keon - Kim Seung-chun (B), 27h
2004-12-26b: Chang Hao - Ch'oe Ch'eol-han (B), 59e

Summary:
- no komi games: 6 wins by the attacker, 0 wins by the defender
- komi games: 2 wins by the attacker, 1 win by the defender
- total: 8 wins by the attacker, 1 win by the defender

Conclusion:
The four-space extension wins in 11% of the games and loses in 89% of the games if the attacker plays the keima punishment.