John Fairbairn wrote:
There was a thread recently in which I queried whether a shape that others saw as thick (i.e. good) was really potentially weak to a pro's eyes. I couldn't prove it, of course, but said it reflected my observations that pros typically cast aspersions on the strength of groups far earlier than we do, sometimes apparently with x-ray eyes. I had to take quite a bit of stick, even though I was just reporting an impression.
I came across yet another example today, and in some respects it was remarkably similar to Iceberg. It may illustrate why I get this impression.
This was the position:
The context is Sonoda Yuichi demonstrating (in his book I mentioned in the "Slew of books" thread) how to perform positional judgement throughout a game. This was a game of his with Honda Kunihisa.
I'm going to have to omit a lot of the background to his PJ approach, but essentially it consists in establishing the current conditions in terms of a short series of criteria, one of which is to establish which areas still have stones that are not alive. This is applied to the right and lower portions of the current position because of a couple of other criteria I am omitting to do with attacking.
Now, judging by the comments in the iceberg thread, there will be people here who point to the centre Black group as thickness and will say that it is alive (one eye on the side, etc.).
But Sonoda's assessment of areas where stones are not alive is: "Black's group in the centre, Black's group on the lower side, White's single stone on the lower side and Black's single stone on the lower side."
It seems to me that the Black groups are alive in the ordinary sense that each one can survive by responding to an attack. They are not alive in the sense of already having two eyes. I wonder what Sonoda would have to say about the Possible Omission Number.
Quote:
Nowhere does Sonoda refer to this central Black group as thickness, even earlier in the game when this central position was being formed. Equally, he does not specifically say it is weak - he just says it is not alive (though since that is used as a criterion for deciding subsequent strategy, some sort of potential defectiveness is being implied). When the shape was formed, he simply said of Black's play that he had no reason to be dissatisfied, and in the immediate lead-up to the current position he makes a reference to a growing Black moyo from the left side to the centre.
In a nutshell, I think Sonoda is making a different assessment of this group than people here (including me) would make.
No quarrel there. However, I find it hard to think that he does not regard the group as thick for the dual purpose of attacking the orphan White stone and providing safety for the orphan Black stone.
Quote:
Sonoda also has interesting things to say about tactics. One applicable here is that when you have more stones than your opponent you use them orthogonally and if you have fewer you use them diagonally (there is also separate advice to "cut the opponent's diagonals"). Hence the right move here for Black is N4.
IIUC, Wilcox's theory says to play the one space jump (another diagonally related play) because it cuts the sector line between the White stone on L-04 and the White stone on R-06, which N-04 does not do. However, the jump lets White play a peep, which strengthens the White orphan, and N-04 threatens to connect underneath to the Black group to the left.
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John Fairbairn
