Remember those adverts that begin "8 out of 10 housewives prefer X" and you always wonder about the other two? In my case I give them a little cheer, but still...

In that light, consider the joseki below. Go to Black 19. This and White 18 are not really part of the joseki.



The question now is how should White connect?

In a game I am looking at, White, a 3-dan, plays A. In eight other known pro games White plays at B seven times. The one other case is at C.

In the present game, Murashima Yoshikatsu, then 5-dan and a very good commentator, highlights A for an extensive comment. He remarks that its idea is to have an effect on Black's corner, but this is really so far into the future, and speculative even then, he recommends regarding B as the joseki. This B applies more pressure to the Black group to the left. In addition, it gives White an option to play a two-step hane with D, E, F without worrying about being cut off. C he describes as "extraordinarily bad". Despite that, a 9-dan pro (Takagi Shoichi) did play it. Speculating as to why, perhaps he regarded it as good because it had the effect of Black having committed the cardinal sin of peeping at a bamboo joint? His was the latest game (1986). Is this the latest thinking?

However, several other interesting things emerge from this opening.

First, Murashima made no mention of potential ko threats (B leaves one) or of two ugly empty triangles. My hunch is that amateurs would have latched on to those aspects first. I did. Does this mean I/we are perhaps too obsessed with trivia?

Second, White 12 is regarded as very important in this joseki. It is useful to consider why.

Third, it is very difficult to evaluate this kind of joseki in any sort of numerical way. There is no obvious split between influence and profit, and it seems very hard to imagine turning White's stones into thickness. How do we go about evaluating it? (The joseki books talk about White mitigating the effects of Black's pincer.)

Fourth, for the language mavens, Murashima twice uses joseki in its common, though not prime, meaning of "(recommended) best move" when it has never or rarely been played before.

But surely the most interesting point is that two out of nine pros preferred margarine and the 9-dan of the two played an "extraordinarily bad" choice.

Isn't Takagi Shoichi know for his individualistic approach to Go. So it wouldn't surprise me if he was well aware everyone else thought B was better, but thought he'd be different just because he likes to. C does also have another minor plus of taking a liberty off the black peeping stone which could come in handy at some point; for example if white gets a stone at m16 and then n16 then after black n17 the o17 cut is now an atari (which is admittedly pretty speculative, but not as much as taking a liberty off the corner with A I feel). Though I agree the plus of B allowing that two-step hane is bigger.

P.S. Yes I would notice the empty triangle, but that would only encourage me to play it as I take particular pleasure in playing good empty triangles and showing the much-maligned empty triangle some love

I like 'B'. The black stones on top could become a weak group.

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be immersed

From the standpoint of White's shape, there is hardly any difference between A, B, and C. (Did Takagi make the bamboo joint to avoid bad shape? Gack! Surely not.) But it seems to me that B is the shape point, because it prevents Black from playing there to make a Tiger's Mouth. (One common mistake in the West, I think, is regarding shape in terms of the configuration of one's own stones, instead of efficiency in the local region.)



It is difficult to evaluate any joseki numerically. People do it, though. I do too, with a margin of error of 4-5 points. Whoop-de-do!

I don't think that we can really evaluate this joseki without evaluating the White counter-pincer, and that depends on what is in the top left, at the least. Much of the influence of the White stones on the P file has been transferred to the counter-pincer. I think that falls under the heading of mitigating the effects of the Black pincer. In addition, Black has been forced low in the top right. is an important move for accomplishing that.

My concern, as White, would be to avoid becoming heavy.

It seems obvious to me that in terms of influence, B is better than A and A is better than C. I can even put numbers on the differences, with an error of much less than 4 points. By my calculations, B is about 0.2 points better than A and 0.9 points better than C. That is in line with Murashima's "extraordinarily bad" assessment. (Yes, friends, a 0.9 point loss to par is extraordinarily bad. It is like Takagi playing an amateur shodan move. Yes, amateur shodans play extraordinarily badly, from the perspective of a pro.)

Why did Takagi play C? Perhaps he had thoughts of playing O-17, as Uberdude suggests. Perhaps the influence of B was not important, given the whole board. Just because it may lose a point to par on average does not mean that it is bad on any given board.

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

Visualize whirled peas.

Everything with love. Stay safe.

Bill, how are these calculations performed?

With an influence function that I developed some years ago. As my remark about its errors indicates, I am under no illusion about its general value. Usually it gives results close to DrStraw's approach.

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

Visualize whirled peas.

Everything with love. Stay safe.

Mitigating the effects...I'll have to remember than next time I have an eyeless group between two opposing groups.
I'm not running, I'm mitigating.

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Help make L19 more organized. Make an index: https://lifein19x19.com/viewtopic.php?f=14&t=5207

I myself have been known to mitigate the whole board.

That's nothing! Sometimes I mitigate my own moves!! Heh...

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- Bantari
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WARNING: This post might contain Opinions!!

The choice among ABC depends on the positional context.

After move 19, it is easy to evaluate the joseki by applying my joseki evaluation method:

The stone difference is 10 - 9 = 1.

The territory count (of 'current territory') is 8 - 4 = 4.

The influence stone difference is 2 - 3 = -1. (In White's favour.)

Territory count and influence stone difference favour different players, as it should be.

The stone difference can be transformed to another white influence stone [imagined to be played elsewhere on the board], giving the modified influence stone difference -2.
The ratio is | 4 / (-2) | = 2.

This value is in the valid range from 1.5 to 3.5 for values denoting josekis.

The weak black and the weak white group are similarly weak, therefore the ratio meaningfully expresses to have a joseki.

Nevertheless, there is the unshown global positional context, which might favour Black, favour White or be equal / fair for both players when choosing this joseki. (The local numerical joseki evaluation does not claim to be a global positional judgement.)

In order to evaluate the joseki, imagine white's P17 were at O16 instead. Would you feel white is better? Would robert's method yield different quantics?
Yet white's shape is much better.
What offsets white's clumsy shape? The fact that black is low?

My method applies to josekis, joseki-like, or almost-joseki sequences because it is calibrated for equal play. It does not apply if one player gets all the good moves and the opponent plays rubbish or the shape is an arbitrary middle game part of the board with no local guarantee of fairness. If you want to let W play where B has a stone, you need to show a new sequence and we can judge if it is meaningful in order to see whether my method is applicable.

Do you have a method which evaluates if a sequence is meaningful?

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- Bantari
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WARNING: This post might contain Opinions!!

Not what I would call a "method". A meaningful sequence consists of meaningful moves, i.e., moves achieving some good purposes such as increasing territory well, increasing influence well, achieving another strategic purpose well or achieving a combination of such aspects well. (This affects also the discussion of choosing among ABC. Maintaining connection is a good meaning but one should also strive to optimise the additional meaning of the move.)

Hmm... so you have a method to evaluate something, but no method to tell you if you can or cannot apply the first method to begin with?

Interesting...

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- Bantari
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WARNING: This post might contain Opinions!!

A pseudometamethod?

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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).

1) It depends on what one calls "a method". For go theory, I am defensive with using the word only for step-by-step advice with very clear specification of each step and of the order in which to proceed from step to step. The joseki evaluation method is clear enough to deserve the attribute "method". The context of having a meaningful sequence, or a position which must have been created by a meaningful sequence, I have not worked out sufficiently precisely yet to deserve the attribute "method". What you see here is that I have not solved the entire go theory yet but I have only reasonably solved part of all go theory. You may scold me for not having solved the whole game yet but only done better than everybody else by reasonably solving the numerical joseki evaluation part;)

2) Although I cannot supply a method yet for judging whether a sequence is meaningful, I have provided lots of aspects and related principles relevant for such a judgement. A meaningful sequence must consist of meaningful moves. A meaningful move is a move achieving good purposes for its player and avoiding clearly inferior "purposes". Aspects for such purposes can be listed: territory, influence, development directions, weaknesses etc etc etc (study strategic concepts, strategic choices, positional judgement, positional context etc). For each such aspect, the player prefers his advantage and the opponent's disadvantage. So there are related principles, such as "a move shall increase the territory count in the player's favour and avoid decreasing it", for every aspect. Furthermore, the combination of all such aspects should be advantageous for the player and disadvantageous for the opponent. Finally, the combination of all such aspects should be as good for the player as possible. Especially concerning this combination, go theory has not evolved far enough for the general case of an arbitrary whole board position. Distinguishing meaningful from bad moves remains in part ambiguous. However, in practice, it often is clear. E.g., playing a neutral stone hardly achieving anything is clearly worse than playing a territory-making, influence-making or own-weakness-eliminating move.

However, when we are not confronted with the general case but have a joseki-like situation, the judgement whether a sequence is meaningful and its moves are close to being as meaningful as possible is much clearer because the most important aspects (stone difference, territory, influence, other major strategic advantages, other major strategic disadvantages) can be judged very well in almost all cases. Besides, these few (classes of) aspects suffice for the local judgement. A meaningful-assessment of these few aspects suffices to feed my joseki evaluation method.

So although the presuppositions of what constitutes a meaningful sequence cannot be described as a method in general case, the lists of relevant aspects and principles relevant for a joseki-like situation are good enough to suggest how future research can work out the combination of these things to develop another method. (Even better: I have provided definitions or sketches for definitions for the low level terms, which would be applied for that other method.)

3) My joseki evaluation method presumes close-to-equality of both players' moves so that it is meaningful to relate one excess move to a) 7 points komi, b) 1 extra influence stone or c) playing of a joseki follow-up. This means that the method requires meaningful, striving-to-be-optimal moves by the players so that is it meaningful to relate every move to one of the optimal ideals (a), (b) or (c). Contrarily, too bad moves must not be related because their value does not equal, and cannot be viewed to approximate, a move of such ideal value. I.e., although there is no method for the general case of any good or bad moves, one can be the more confident the more the moves approach the ideal of having such meaning. One can judge the results (of the aforementioned aspects) also after a sequence of good and bad moves, but one cannot necessarily be sure any longer from my joseki evaluation alone whether the sequence is joseki-like because it measures the results but does not detect whether the result might have been created by also bad moves, of which some might cancel each other.

I have an idea: apply my joseki evaluation method after every move. If it says "balanced" at each moment, then each move can be viewed as "good". This presumes the move sequence is given. (Of course, it does not work when somebody wants to discuss an illegal sequence by rearranging a stone where there is another stone.)

4) Instead of trying to let sound my joseki evaluation method irrelevant because of not also solving the entire go theory immediately, you should appreciate how frequently applicable and meaningful it is in joseki-like situations because, in practice, it is very often possible to distinguish meaningful from meaningless moves. Difficulties arise only when one wants to achieve more and distinguish margerine from butter so as to choose the best joseki move variation in the global positional context.

Robert, as I understand this and a similar earlier remark, you are saying that you assume that some individuals (pros) or a collective of individuals have already "solved" go theory and come up with sequences that are widely agreed to be equal. What you have done is to provide a numerical method, which you regard as superior because it can be applied by non-pros. Pros have used another but opaque method (and were first). Is that right?

A problem I have with that sort of approach is that it's as much like mathematical rigour as a beauty pageant. A group of women (qua opening sequences) who have already been told by friends, relatives, prom nights, etc that they are beautiful (qua evenly assessed joskeis) are put forward for a so-called rigorous evaluation in which a panel uses numbers to grade each contestant. 1-5 for a curvaceous figure, 1-5 for "personality", etc). By and large they end up with a winner that causes little controversy, so they can claim to have "solved" the evaluation of beauty.

But the problem is that the panel is part of the same cultural background as the friends and relatives, so they are not really measuring anything - they are just applying the same (pseudo)cultural norms. In other words, such methods are circular.

I can see the value of your method for a computer. But for a human I have doubts. In fact I could claim you are demeaning josekis, objectifying them as numerical objects. Ban joseki books! Josekis of the world rise up, and burn your bikinis!

Did anyone comment on the second point. W12 seems to be important due to the presence of N15, old coffee for most commenters it seems, but maybe beneficial to others reading this thread.

Click Here To Show Diagram Code

[go]$$W Not played - White shut in
$$ ------------------
$$ | . . . . . . . . .
$$ | . . 1 . . . . . .
$$ | . X O . O . . X .
$$ | . . X O . . . . .
$$ | . . X 3 2 5 B . .
$$ | . . . 4 O 6 . . .
$$ | . . X . . . . . .
$$ | . . . . . . . . .
$$ | . . . . . . . . .[/go]

John,

I am not saying that some would have solved the entire go theory. In reply to Knotwilg, Bantari and DrStraw, I have said that my method should not be depreciated on the grounds that I (nor anybody else) has risen everything of related go theory (and ultimately the entire go theory) to the same standard as my method, and that therefore not everything else should already be called a "method".

I do not regard my method to be superior because of being applicable by non-pros. It is superior because

- it can be applied by non-pros and pros (and, with some extra effort, even programs),
- this is so independently of a consensus of professionals' opinions on what is or is not joseki,
- this is so independently on how frequently applied some sequence has been in (especially professional) games,
- therefore the method is applicable during one's games and one need not wait years until possibly some professionals express opinions, reach a consensus or apply particular sequences sufficiently frequently to allow for empirical data,
- it is applicable to every joseki-like local position (applicability rate ca. 99.75% for josekis that do not necessarily immediately evolve as middle game fights and therefore mainly depend on the positional context)
- AFAIK, it is the only joseki evaluation method systematically relating the stone difference to territory and influence,
- AFAIK, it is the only joseki evaluation method expressing amounts of influence at all and therefore allowing systematically relating influence to stone difference and territory,
- AFAIK, it is the only general joseki evaluation method almost always allowing to distinguish josekis from non-josekis,
- AFAIK, it is the only joseki evaluation method explaining different joseki value types (such as 'ideal equality' or 'territory versus influence) by a common, consistent evaluation scheme.

Professionals have not used only one other "method", but they have been, and are, using a variety of "methods", such as tewari or 'forming a consensus by trial and error'. All such methods have some use, but fail to be generally applicable and achieve the aforementioned advantages.

I do not share your scepticism about numerical approaches. Numbers of stones and their difference are numbers. Amounts of territories and their difference are numbers. Numbers of outside influence stones and their difference are numbers. Komi is a number. The number one of an influence stone elsewhere on the board is a number. The territory per influence ratio is number. My statistics that every ordinary joseki has a ratio between 1.5 and 3.5 relies on numbers that can be checked by recalculating them. I do not care about whether beauty can be expressed in numbers, but I care when numbers can be consistently used in a method. The method and its theoretical foundation let such numbers have good meaning.

The method is not circular. Of course not. You should know better. Study the entirety of my research results and you will notice that I start with the rules, go to the lowest level terms and work my way up to the higher level terms and concepts. There may still be some gaps, but the bottom-up structure is there. My joseki evaluation method applies first move value, stone difference, territory count and influence stone difference, which I have already defined (sometimes formally, sometimes with less rigour). There is no vicious circle.

Your doubts about human applicability are refuted the most easily: I apply, and profit from, my joseki evaluation method in my games or discussion about games. It is straightforward to determine stone difference, territory count, influence stone difference, calculate the ratio, interpret it etc; everybody can do so if only he wants to learn and apply.

Of course, I am not demeaning josekis. Quite contrarily:

- the method appreciates josekis as something so outstanding that it can even be recognised numerically,
- the method is deliberately approximate (exact values are not necessarily required) and flexible (applicable to different joseki types, ackowledging dominating strategic concepts, having a variety of value transformation options) to allow for a variety in josekis existing or to be discovered later,
- the method can be embedded in almost arbitrary global positional contexts.

Of course, my method does not oppose joseki books. Quite contrarily, it confirms, summarises and combines (most of) their assessments. However, my method greatly enriches the scope of what traditional joseki books tell their readers. There are times when I criticise traditional theory as wrong. Traditional joseki theory is not wrong - it is "only" lacking generality of evaluation and consistent discussion of strategic decisions. My method goes beyond traditional understanding to raise joseki understanding to a new level of evaluation.

EDITED