A joseki with greater inside thickness
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RobertJasiek
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A joseki with greater inside thickness
My comment on this joseki has been that the black group, which is mainly on the inside, has the thicker shape so that the slightly disadvantageous territory/influence ratio can be tolerated.
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tchan001
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Re: A joseki with greater inside thickness
I would think that normally joseki is shown with the move orders rather than just commenting on the final results.
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RobertJasiek
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asura
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Re: A joseki with greater inside thickness
RobertJasiek wrote:[go]$$B
My comment on this joseki has been that the black group, which is mainly on the inside, has the thicker shape so that the slightly disadvantageous territory/influence ratio can be tolerated.
I'd like to ask a general question about your method to evaluate josekis (or if it's a joseki).
As I understand it you assign values for territory, influence, etc.
When you have all the single values can you then compute a value for the whole (e.g. by adding or multiplying them) ?
With "value for the whole" I mean something that a bigger value implies a better result.
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SoDesuNe
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Re: A joseki with greater inside thickness
tchan001 wrote:I would think that normally joseki is shown with the move orders rather than just commenting on the final results.
Note: Black does not need to answer
at 
but can extend to 
. But after W , Black must be able to cut at 'a'.-
RobertJasiek
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Re: A joseki with greater inside thickness
asura, as soon as the local territory count T and the influence stone difference I are known, calculate |T/I|, i.e., take the absolute of the quotient. Simply speaking, values from 1.5 to 3.5 are ok; for greater or smaller values, there must be a compensation for the player having a disadvantageous value. Note: if the stone difference is not 0, more theory is applied.
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Bill Spight
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Re: A joseki with greater inside thickness
SoDesuNe wrote:tchan001 wrote:I would think that normally joseki is shown with the move orders rather than just commenting on the final results.
Note: Black does not need to answer
Thanks, SoDesuNe.
The position did not ring a bell with me.My first thought upon seeing this position was, That's joseki? It looks good for White to me. And it turns out that Suzuki-Kitani say that it is somewhat favorable for White.
My second thought was, Why didn't White push at "a"? The modern sequence has White making that play. Guess I'm not over the hill yet, eh?
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asura
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Re: A joseki with greater inside thickness
Not sure this is the question, but the reason for white making the 14 for 15 exchange before playing 16 is that if he plays 16 for 17 first, then black can hane at A (instead of 15) after white push at 14.Bill Spight wrote:My second thought was, Why didn't White push at "a"? The modern sequence has White making that play. Guess I'm not over the hill yet, eh?
@Robert: For a quotient the range between 1.5 and 3.5 seems quite big. So the main application is to exclude bad variations quickly but not so much to find the best variation inside this range based on the value of this quotient?
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RobertJasiek
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Re: A joseki with greater inside thickness
There are different types of josekis etc., so there is also quite a range of values. (If one side makes territory in the corner, the ratio can be even bigger.) Yes, you might say that it is a first filter of detecting and discarding the truely mediocre and the bad variations. Afterwards, it is still an independent task to choose the best joseki / almost-joseki / variation in a given positional context.
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schawipp
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Re: A joseki with greater inside thickness
RobertJasiek wrote:asura, as soon as the local territory count T and the influence stone difference I are known, calculate |T/I|, i.e., take the absolute of the quotient. Simply speaking, values from 1.5 to 3.5 are ok; for greater or smaller values, there must be a compensation for the player having a disadvantageous value. Note: if the stone difference is not 0, more theory is applied.
I have just a beginner's question: For the black territory, I would count approx 15 points (depending on the endgame(?)). However I'm not sure how the number I for influence is determined. Could you give a numerical example for this position?
Another aspect may be the aji of the dead C17 stone, which seems to be at least good for three successive ko threats (e. g. B18, C19 and E19 if black replies on B17, D19 and C17, respectively). If there is a big ko fight going on elsewhere, white has the potential to gain about 15 points here (the three black stones + a few points of eliminated corner territory). Is that also considered in the numerical evaluation?
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SoDesuNe
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Re: A joseki with greater inside thickness
I don't know RobertJasiek's method but I like one John Fairbairn presented in Games of Honinbo Shuei vol. 3. It was proposed by Abe Yoshiteru 9-dan und looks like this: (n*(n+1))/2.
n are the number of stones from the third line, which build the wall. The idea is to also count forcing moves which would add stones to the wall.
This Joseki would therefor give White at least 15 points ((5*6/)2), with the - exchange, White has 21 points ((6*7/)2). For Black I would count 13 points without the exchange and 15 with it. So it's clear why e.g. Suzuki-Kitani say, White is favourable.
n are the number of stones from the third line, which build the wall. The idea is to also count forcing moves which would add stones to the wall.
This Joseki would therefor give White at least 15 points ((5*6/)2), with the
- exchange, White has 21 points ((6*7/)2). For Black I would count 13 points without the exchange and 15 with it. So it's clear why e.g. Suzuki-Kitani say, White is favourable.-
leichtloeslich
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Re: A joseki with greater inside thickness
(n*(n+1))/2.
n are the number of stones from the third line, which build the wall
It might worthwhile to note that
n(n+1)/2 = 1+2+3+...+(n-1)+n = sum of first n integers
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SoDesuNe
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Re: A joseki with greater inside thickness
leichtloeslich wrote:(n*(n+1))/2.
n are the number of stones from the third line, which build the wall
It might worthwhile to note that
n(n+1)/2 = 1+2+3+...+(n-1)+n = sum of first n integers
Possibly wortwhile.
Speaking just for myself, though: What the ♥? : D
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RobertJasiek
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Re: A joseki with greater inside thickness
The 1 black and 6 white influence stones with significant outside influence are marked. The influence stone difference is 1 - 6 = -5.
Black has, I'd agree, 15 points of current territory. Counting White's current territory is trickier; I count 8 points; this makes the territory count 15 - 8 = 7 points.
Then the ratio is | 7 / (-5) | = 1.4.
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Abe's formula is only a rule of thumb, which amounts to drawing a sector line and counting the intersections inside the created imagined triangle. Instead, determining territory should rely on imagined reduction sequences.
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John Fairbairn
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Re: A joseki with greater inside thickness
Abe's formula is only a rule of thumb, which amounts to drawing a sector line and counting the intersections inside the created imagined triangle. Instead, determining territory should rely on imagined reduction sequences.
There are several things wrong with this, all showing RJ has not read Abe's book - usually a good reason for not criticising or caricaturing it.
First, Abe counts the value of the thickness, not the territory, and so the extension stone does not come into his equation. Ultimately, the value of the thickness has to come down to territory points, but not necessarily in their own vicinity. Therefore his method is not so much a means of evaluating a local exchange (though it can do that) but of providing help in evaluating the game as a whole.
Second, his method cannot be characterised as drawing a sector line dividing a rectangle because the point is that he allows wraparound and irregular walls facing two or even three directions (and also allows for intersection of walls).
Third, although with an entirely difference emphasis he does allow imagined sequences to influence the count. You'll have to read the book to see how.
As a general point, I think we need to remember the hoary chestnut of the difference between precision and accuracy. If I understand RJ's methodology correctly, he is concerned primarily with precision, that is repeatability of his results. Even if he achieves this, they may not be accurate or too local. Abe's method probably has very low precision but he must regard it as being accurate enough to publicise it, and he is recommending it as a whole-board measure. If go is like a dart board where you are given six arrows and you need a 20 to start, using RJ's type of method seems to suggest you might be able to score triple 18 six times of six - close but not close enough, and you would never be able to start. Using an Abe type method, you may drop one dart in your foot and pitch another into someone's beer, but the rest are dotted around the top half of the board and - hey presto - one hits the 20! Game on!
If that happens consistently and pals decide to set up a pub darts team, the sometimes errant tosser is much more likely to be picked over the metronome. Since go, like life, is in practice essentially a probabilistic game where accuracy does better than precision over the long run, pros will presumably always favour the accuracy of rules of thumb (which of course they can tweak on the basis if experience).