Life In 19x19

In a recent comment I told CarlJung that he had missed the opportunity to cut a short sector line. Bruce Wilcox, OC, talks about cutting sector lines. I learned the idea early in my go study, as jumping or pushing through a narrow gap. This is often a strong move, and the narrower the gap, the better.

Click Here To Show Diagram Code

[go]$$B The narrowest gap
$$ . . . . . . .
$$ . . . . . . .
$$ . . . X . . .
$$ . . O 1 O . .
$$ . . . X . . .
$$ . . . . . . .
$$ . . . . . . .[/go]

This example illustrates the idea in its most extreme form. connects and strengthens the Black stones while it separates and weakens the White stones. Similarly, would be good for White.

Click Here To Show Diagram Code

[go]$$B Jump and separate
$$ . . . . . . . . .
$$ . . . . . . . . .
$$ . . . . 1 . . . .
$$ . . O . . . O . .
$$ . . . . X . . . .
$$ . . . . . . . . .
$$ . . . . . . . . .[/go]

Likewise, is good, as it cuts a short sector line.

Click Here To Show Diagram Code

[go]$$B Not so strong
$$ . . . . . . . . . . .
$$ . . . . . . . . . . .
$$ . . . . . 1 . . . . .
$$ . . O . . . . . O . .
$$ . . . . . X . . . . .
$$ . . . . . . . . . . .
$$ . . . . . . . . . . .[/go]

is still a good play, but it is not very strong, as a rule.

----

My impression is that this principle is not widely known in the West. I thought I would share.

Wouldn't the strength of the move in the third example be entirely dependent on context? Or perhaps that's what you are saying, that without another good reason to make such a move, it is not very strong just in relation to the two other stones shown?

Maybe You could say its less severe... basically, the vector cut leaves the opponent with 2 groups to defend, but he has only one move. If the cut stones are farther away from another, its less likely that a severe attack can be launched on the neglected stone.

Heh, the way I always describe attacking to new players is:

It's like basketball, if you try to guard too close, they're just going to blow right by you, you don't have time to react to sudden changes.

Likewise here, if someone guards you too close, cut right by them

Bill Spight wrote:In a recent comment I told CarlJung that he had missed the opportunity to cut a short sector line. Bruce Wilcox, OC, talks about cutting sector lines. I learned the idea early in my go study, as jumping or pushing through a narrow gap. This is often a strong move, and the narrower the gap, the better.

$$B The narrowest gap
$$ . . . . . . .
$$ . . . . . . .
$$ . . . X . . .
$$ . . O 1 O . .
$$ . . . X . . .
$$ . . . . . . .
$$ . . . . . . .

Click Here To Show Diagram Code

[go]$$B The narrowest gap
$$ . . . . . . .
$$ . . . . . . .
$$ . . . X . . .
$$ . . O 1 O . .
$$ . . . X . . .
$$ . . . . . . .
$$ . . . . . . .[/go]

This example illustrates the idea in its most extreme form. connects and strengthens the Black stones while it separates and weakens the White stones. Similarly, would be good for White.

$$B Jump and separate
$$ . . . . . . . . .
$$ . . . . . . . . .
$$ . . . . 1 . . . .
$$ . . O . . . O . .
$$ . . . . X . . . .
$$ . . . . . . . . .
$$ . . . . . . . . .

Click Here To Show Diagram Code

[go]$$B Jump and separate
$$ . . . . . . . . .
$$ . . . . . . . . .
$$ . . . . 1 . . . .
$$ . . O . . . O . .
$$ . . . . X . . . .
$$ . . . . . . . . .
$$ . . . . . . . . .[/go]

Likewise, is good, as it cuts a short sector line.

$$B Not so strong
$$ . . . . . . . . . . .
$$ . . . . . . . . . . .
$$ . . . . . 1 . . . . .
$$ . . O . . . . . O . .
$$ . . . . . X . . . . .
$$ . . . . . . . . . . .
$$ . . . . . . . . . . .

Click Here To Show Diagram Code

[go]$$B Not so strong
$$ . . . . . . . . . . .
$$ . . . . . . . . . . .
$$ . . . . . 1 . . . . .
$$ . . O . . . . . O . .
$$ . . . . . X . . . . .
$$ . . . . . . . . . . .
$$ . . . . . . . . . . .[/go]

is still a good play, but it is not very strong, as a rule.

----

My impression is that this principle is not widely known in the West. I thought I would share.

Bill,

Could you direct a new player to some more information on the web about this concept? I'm specifically interested in knowing more about how sector lines relates to and/or differs from cutting.

Wasn't there already a page on senseis about this? I remember something...

cdybeijing, I really recommend picking up Bruce Wilcox's Sector Fights. It's the source material for all of this, and is really good. I'm still working through it, and not that deep yet, but it is very interesting, and kind of explains things that made instinctive sense in a very different way. It's around 30 bucks, but you get a whole lot of content for the price.

Actually, I've also started watching Bruce's games, and they're always really interesting to watch, particularly while thinking about the way he describes sector lines.

redponey wrote:Wouldn't the strength of the move in the third example be entirely dependent on context?

Oh, yes, in go context almost always matters. That is why virtually every go proverb has exceptions.

cdybeijing wrote:Bill,

Could you direct a new player to some more information on the web about this concept? I'm specifically interested in knowing more about how sector lines relates to and/or differs from cutting.

I am pretty sure that I wrote something about this on Sensei's, but I could not find it when I started this thread. {shrug}

As for sector lines, as Chew Terr says, Bruce Wilcox's stuff is probably best. Not too long ago John Fairbairn found an article from the 1960s (IIRC) that mentions sector lines (not by that name, OC), but only in regard to reduction.

Chew Terr, where can you watch Wilcox's games?

It's not his games, it's a software CD: http://webpages.charter.net/suewilcox/Sector.htm

His software is great, but I was saying that his games themselves are interesting and helpful. Lately I've seen him online a lot, so I drop in to observe. His name is something obvious like bwilcox, but I'll check and post it when I get home.

Edit: checked on sensei's, and his kgs name is, in fact, bwilcox.

Ah, forgot that part of the post. :p