Block on the wider side

  Difficulty: Intermediate   Keywords: Opening, Joseki, Proverb

 
Table of contents Table of diagrams
The 3-3 point invasion
An example
A second example
Second example played out
Black to play
Block from the wider side
Blocking from the smaller side

Block From The Wider Side

Blocking from the wider side means that you yourself will get more potential for territory

3-3 point invasions under 4-4 points

[Diagram]
The 3-3 point invasion  

This Go proverb is meant for the situation in this diagram: White has just invaded at the 3-3 point below Black's 4-4 point (see 3-3 Point Invasion). On which side should Black block, at a or at b? The general rule is to block where your extension is wider or the potential moyo is larger.

[Diagram]
An example  

In this diagram black+circle is further away than black+square (so it is the wider extension), so Black blocks at B2 rather than a.

[Diagram]
A second example  

Here black+circle and black+square are at the same distance, but if one looks beyond it, the upper moyo still extends further than the left one, so again B2 is the correct move.


Emptyriver- Sorry, but could you explain this a little more. It seems like Black will want to protect the weaker side (the territory on the left side seems less secure) from White's influence.

Jasonred If I'm not mistaken, the joseki does protect the weaker side. Anyhow, influence? what influence? This usually leads to White gaining some territory, and Black gaining influence, no? Of course, this is only joseki at kyu level, but good enough, I guess. Even at kyu level, I wouldn't want to be White in this sequence, as the board was just too open to trade off the territory from san-san invasion for that wall!

[Diagram]
Second example played out  




/Discussion



Checking extensions

[Diagram]
Black to play  

tderz: Blocking from the wider side means that you yourself will get more potential for territory, while the opponent will get less space, even lacking stability.

Black to play: a or b? [10]


[Diagram]
Block from the wider side  

Correct: Black gets a wide extension B1 from his black+circle-shimari and induces the natural corner moves B3+B5.

The white position is cramped, imagine a (later) black move a!

[Diagram]
Blocking from the smaller side  

Incorrect: the black+circle-shimari is devalued, the white+circle extension is less cramped than in the correct diagram and
if Black closes the corner now with a, there are still later "imponderabilities" as b etc.


[10] Source of diagrams (adapted, TD): Guo Juan, Teaching Go at different Levels, Nov. 2002, (advice for 1-5k)


Block on the wider side last edited by 81.107.203.93 on November 29, 2009 - 12:29
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