When White makes a kakari to the 4-4 point with , it is common for Black not to answer in the corner, but play tenuki (or make a pincer on the left side).
If White gets to play a second move here, the most usual choice is a second kakari from the other side with (or a). Such a position is called a double kakari.
After White makes a double kakari, Black will usually react, because after a White play at b, Black just barely lives in the corner while White gets superb influence.[1]
Black a (or c) is the most common way, while Black b is a good alternative for weaker players, because it avoids difficult variations.
Charles Matthews I don't agree that Black b is better for weaker players: in this case fixing the shape with a is more promising. What you can say is that the diagonal play answer at b has experienced a revival in pro games, associated with new thinking about central influence and possible tenuki variations.
After here,
at the 3-3 point is normal; and now Black plays a, b, or tenuki allowing White at a.
The problem with this joseki for a weaker player is that Black at a can leave a black wall, but without a pincer attacking and also with some potential shape problems. Clearly this isn't troubling at pro level, but amateurs can come to grief here.
After Black's main options are at e, f and g. Playing g, which is a move useful in handicap games when Black has a stone already at the circled point to attack
, isn't very forceful here. Black at e is only seen in old games.
Probably is the best idea here, but the bulge play
gives Black some shape difficulties. In games of Hane Yasumasa based on the Chinese opening Black h, White i, Black j was used to build influence for Black on a large scale, treating the cutting point at the circled point as secondary.
This would be a big mistake as it doesn't take advantage of Black's shape problems.
Dieter: This is considered joseki today.
Charles I can't confirm that this is played at all.
When is present, yes, this is played in many pro games.
See also:
[1]
Evand What are the standard continuations if Black plays tenuki again and White plays b? Under what circumstances is tenuki there a reasonable play?
Charles See discussion on the J groups page, under 'Practical application'. But it is considered poor to allow the shutting-in play. Cf. BQM 48 for cases where Black has two pincer stones on the outside but still wants to be a move ahead in the fight after being shut in.
firstian As a beginner, I'm always looking for the "meaning" of a move, so I can think about whether a move makes sense or not, and also how to respond when my opponent doesn't play a book move. I think I understand that either a or c are meant to separate the two stones and develop on one side. What about the meaning of b? For example, in one of my 9-stone handi game, W played:
I think the correct response to is a. But not knowing what
is suppose to do, I have no clue how to develop my corner group. (My guess is that
helps B runs out to the center, but is that it?)
20k guess: leaves two possibilities - live in the corner, bigger than if
hadn't been played (eg with 3-3), or run into the center (eg with b). In a nine handicap game, black probably isn't clever enough to tell which is better. Therefore, treat them as miai and play somewhere else.