Attachment on the second line
Once Black attaches at , two common responses for White are a and b.
is a solid line of play. Black gets additional territory and White gets solidity facing the right hand side.
This works well for White when White has stones to the right at a or b. White stones closer than that would yield an overconcentrated shape.
Alex Weldon: If the White stone is much closer (say at c, especially if the ladder towards the upper right is good), or if Black is playing this too early in the game, and White is willing to play lightly, it may be possible to omit . This would make the sequence gote for Black.
If White chooses to capture with the hane at
,
forces White to play
to complete the capture of
.
Black will then roll over top of White with . Black obtains outside thickness, while White gains some territory. For White to resist
by playing
there herself is inconsistent with
.
Velobici: Such is this 10k's understanding. Please correct my errors and enrich this page.
Charles I saw a 4 dan and a 7 dan discuss this, last year. The 4 dan said he'd automatically play above; the 7 dan commented that the 4 dan needed to change his entire attitude to the game. So, who am I to comment?
Actually, this is one of the most basic middlegame joseki. Even so, you have to look at crawl lines to understand the local tactics.
Here is natural resistance.
Black has several choices: at a, at b and possibly some ways to fight out with .
If Black avoids complications, up to is expected.
Clearly here White has played in a territorial way, and Black has gained in influence.
This contact play technique is particularly useful for making shape for cramped groups on the side. It is quite common to reinforce the two-space extension.
In reply to ,
builds strength. White is defending, but now there is a chance of White a to cut in the centre. (From An Yeong-kil-Ch'oe Myeong-hun (B) 2001-06-07.)
Again White plays contact with . This time Black answers solidly with
, to keep up the attack.
In the end strengthens the centre. Here attack and defence are well balanced.
Further examples: