Question for Bill

Bill Spight · Post by **Bill Spight** » Wed Jun 14, 2017 11:38 am

John Fairbairn wrote:I'd go further and say that all amateurs should try a sustained period of playing thickly like this, because it teaches patience and so takes you much deeper into the game.

I heartily agree, as you know.

The narabi/nobi complex of moves is often underestimated. It seems to have become more popular around Shin-Fuseki times, interestingly at the same time as Hypermodern chess, and when Nimzovich first propounded his concept of prophylaxis. I read recently that most of Nimzovich's ideas have not really survived into modern chess strategy, but a shining example is prophylaxis. Maybe the same realisation has occurred in go.

Oh, it seems to me that the idea of prophylaxis goes way back in go. Here is an example, from a Castle Game over 300 years ago:

Click Here To Show Diagram Code: [go]$$Bc Dosetsu (W) - Yasui Senkaku, 1698 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . 6 . . . . . . . . . 7 . . . . | $$ | . . 0 , . . . . . , . . . . . , 5 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 , . . . . . , . . . . . , 8 . . | $$ | . . . . 2 . . 3 . . 9 . . . 4 . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

-

was the style in those days. :b9:

is the prophylactic move, preventing a counter-pincer. I think that it was joseki back then, as it occurs in other contexts.

Click Here To Show Diagram Code: [go]$$Bcm11 Low extension $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . O . . . . . . . . . X . . . . | $$ | . . O , . . . . . , . . . . . , X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . 1 3 . . . . . . . . . . . . . . . | $$ | . . . 2 . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 8 . . . . . . . . . . . . . . . | $$ | . . . 4 7 . . . . . . . . . . . . . . | $$ | . . X 5 6 . . . . , . . . . . , O . . | $$ | . . . . O . . X . . X . . . O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Just a bit of the continuation.

was joseki then, but it is too low. :w12:

is a refutation. :b13:

avoids getting pressed down, but then White has :w14:

. I find it interesting that the ancients knew how to take advantage of :b11:

without realizing that it was inferior.

The rest of the game is interesting. I like how White takes the bottom left corner, sacrificing a number of stones.

RobertJasiek · Post by **RobertJasiek** » Fri Jun 16, 2017 1:48 am

A detailed positional judgement, sophisticated analysis or arcane terms for what simply is attack and defense are not needed. Even the roughest count tells us W leads on territory. To maintain his lead, he must defend some of his 3 weak groups. He defends the central weak group so as to also indirectly defend his other two weak groups. If instead he defended one of his other weak groups, he would be indirectly defending only one further weak group. Defending 3 is better than defending 2 weak important groups.

Simple.

John Fairbairn · Post by **John Fairbairn** » Fri Jun 16, 2017 3:47 am

Even the roughest count tells us W leads on territory. To maintain his lead...

But White lost, and there were no special tactical excitements such as kos or captures, and no mistakes were mentioned. Instead, Black said, shortly after this position, "I was confident" and White said, a little later, "I thought the game was close but I just didn't have enough."

Of course White was only a Japanese 9-dan, but I expect he and Black saw the bad aji on the lower side (where White got only 24 points and Black got a huge right corner). The bad aji is exacerbated by the continuing weakness in White's left centre group forcing him to defend in a way that let Black connect his own left centre group at J5.

Uberdude · Post by **Uberdude** » Fri Jun 16, 2017 4:14 am

This position under discussion reminds me of a decision I faced recently in the British Challengers' league vs Andrew Kay:

I was white and black had just connected at the marked point following my invasion of the lower side (full game at http://eidogo.com/1XbHEBGLq ). The two main moves I was considering were a, a prophylactic move for my centre group, and b, solidly completing the lower side shape and in theory meaning the 3-3 is killable but with bad aji along the right side. If I don't play a move there black c is quite annoying: if I then answer at b black can comfortably live in the corner, and if I hane in the corner my 5 stones can get in trouble so I didn't actually gain much from invading the lower side. Taking gote to finish off is I believe usually considered a good result for white who gained a lot of territory, the issue is how much profit can black make from them attacking/bullying the white centre group with the thickness I have him. My initial feeling was to defend the centre group with a move at a, but after some thought I decided I didn't like that as 1) black d was still sente and I couldn't find an answer better than e which felt slack shape (and d is useful for black against white invasion at f later) and 2) wantd to get real profit at lower right. I also thought about white d or attach, but didn't like either. So in the end I played b for cash, daring black to attack, which he did at d and I answered with a fancy-pants attach. I wasn't particularly happy with the shape I got in the game, what do people think would be best or am I already in trouble? Perhaps my invasion of the lower side was not good, or move 36 (e8) should have been one line further at e9.

Click Here To Show Diagram Code: [go]$$Bc British Challengers 2017 round 5: Andrew Simons (me) 4d white vs Andrew Kay 4d black. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O X . . | $$ | . . . . . . . . . O . . O . . O X . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . X . X . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . f . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . d . a . , . . . . . O . . . | $$ | . . . . . . e . . . . . . . . . . . . | $$ | . . X . O . . . . . . . . . . . . . . | $$ | . X . . . . O . . . . . . . . . . . . | $$ | . X O O O . . O . . . . . . . . O . . | $$ | . O X X . X . . . B X X . . . . . . . | $$ | O . O X . . X . . X O X O b . O . . . | $$ | . O O X . . . . . X O O O X . c . . . | $$ | . O X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

RobertJasiek · Post by **RobertJasiek** » Fri Jun 16, 2017 4:51 am

John Fairbairn wrote:White lost, and there were no special tactical excitements such as kos or captures, and no mistakes were mentioned. Instead, Black said, shortly after this position, "I was confident" and White said, a little later, "I thought the game was close but I just didn't have enough."

Of course White was only a Japanese 9-dan,

If we see the game sequence, we can replace such nullarguments and failure to point out mistakes by mentioning some.

but I expect he and Black saw the bad aji on the lower side (where White got only 24 points

24 is expected.

and Black got a huge right corner).

Of course, Black gets something from the still weak W groups.

Bill Spight · Post by **Bill Spight** » Fri Jun 16, 2017 6:18 am

John Fairbairn wrote:
Even the roughest count tells us W leads on territory. To maintain his lead...

But White lost, and there were no special tactical excitements such as kos or captures, and no mistakes were mentioned. Instead, Black said, shortly after this position, "I was confident" and White said, a little later, "I thought the game was close but I just didn't have enough."

In another thread recently, someone asked if pros had something analogous to the value network of AlphaGo, that directly gave a precise positional evaluation, noting that the pros relied upon counting territory a lot. I think that this indicates that the answer is yes, but the evaluation is not all that precise. At least before the endgame.

Bill Spight · Post by **Bill Spight** » Fri Jun 16, 2017 6:56 am

Uberdude wrote:This position under discussion reminds me of a decision I faced recently in the British Challengers' league vs Andrew Kay:

Click Here To Show Diagram Code: [go]$$Bc British Challengers 2017 round 5: Andrew Simons (me) 4d white vs Andrew Kay 4d black. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . O X . . | $$ | . . . . . . . . . O . . O . . O X . . | $$ | . . . X . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . X . X . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . f . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . d . a . , . . . . . O . . . | $$ | . . . . . . e . . . . . . . . . . . . | $$ | . . X . O . . . . . . . . . . . . . . | $$ | . X . . . . O . . . . . . . . . . . . | $$ | . X O O O . . O . . . . . . . . O . . | $$ | . O X X . X . . . B X X . . . . . . . | $$ | O . O X . . X . . X O X O b . O . . . | $$ | . O O X . . . . . X O O O X . c . . . | $$ | . O X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

What do you think of a move at "d"? As you say, it is a natural point for a Black attack and if White plays there, White has follow-ups on the left side.

Uberdude · Post by **Uberdude** » Fri Jun 16, 2017 7:55 am

Bill, I replied in my study journal so we don't derail this thread.

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