|Table of contents||Table of diagrams
The 3-3 point invasion
The Standard Joseki
The joseki continues
The 3-3 point invasion
Preventing the invasion
Changing the order
don't let white settle in the corner
White shouldn't worry
A more serious attack
A more serious attack
Black shouldn't worry
Many weak players fear the invasion of in this diagram. Playing Black, they have the idea that their corner territory is taken away, and are, in a sense, correct. After , it is White rather than Black who will make territory in this corner.
The 2-2 Point Invasion of a 4-4 point at c is typically incorrect, and can be considered a trick play. The idea behind this move is that Black would end up with a heavy group by trying to kill the invasion.
Nevertheless, Black should welcome this invasion. Black shouldn't see this move as an attack on Black's territory; the 4-4 point is not meant to take the corner, but to make thickness and seek a balance between territory and influence. The white invasion at is separated from the rest of the board by the black stone on the 4-4 point. By playing correctly Black will get a strong position. Because of this, stronger players play only if the position on the edges is such that a white stone at a or b will come under attack.
White, for his part, should resist the temptation of invading here too soon. The general principle is that White should seek to invade at the move before black would protect the area.
To Black will invariably answer with (or Black at , on the other side).
To choose which way to block, the general rule here is to block on the wider side, seeking to maximise the usefulness of the outside strength black is building.
ensures that White's corner will not be too small.
is an important move, preventing white from making progress out into the centre.
White plays at to avoid Black playing at the same point.
Usually crawling along the 2nd line is bad, but is important to prevent Black turning here in sente. White should resist the temptation to continue crawling at a. Every extra point white takes, is far less valuable than the outside strength that Black takes.
This result is regarded as good for Black locally, but is often White's best choice, nonetheless. Later in the game the cut at a might be a problem for Black, see Squeeze for more discussion how and when to defend. See Hovercraft for Black attacks on the corner and the proper defenses.
With the knights jump black can get sente, if the upper side isn't very important.
The usual way to prevent the 3-3 point invasion is a stretch at or a depending on where friendly stones are nearby. The one-space jump at b and the diagonal at c can also be used, though they are seen less frequently.
This shape is also seen in situations like this, where White has played an approach move, with the same intention of preventing the 3-3 invasion
The diagrams above cover the most basic moves, but unsurprisingly, (this is Go, after all) there are more complexities and subtleties that one can investigate:
If black seeks to get more by playing at in the diagram below, then he risks disaster...
here instead of in the joseki ( in this diagram) is overdoing things. After , Black has problems.
White could also attack the black stones at the left with these moves. Either way, White has destroyed Black's thickness, and has good chances of getting even more.
Charles I've seen a pro as White play directly at after here.
W plays the reverse order
Here White swaps the order of play, turning at before playing the hane at .
The danger is that Black may be able to answer with rather than the usual . This lets Black shut White into the corner with (particularly as 'a' is Black's sente). White ends up with a smaller corner than in the joseki, and Black may be in a position to make territory on the left. The disadavantage for Black is the aji of the cut at 'b'.
B tries to kill the invasion
If black is already very strong on the outside, then letting white live small in the corner, overconcentrating the new black wall is a bummer. Instead, black can try to kill the 3-3 invasion by undermining the eyespace in the corner and forcing white to run out into the center where sufficient black resources can deny white outside eyespace and a route to safety. How to undermine the eyespace in the corner?
Follow-ups and/or expansions welcome here.
In fact directly, in reply to is a more refined version of this technique. There are a few contexts in which it is strong.
erikpan: Just a quick question: Is there anything wrong with ? I've had some success with it, admittedly at the 16k-ish level. When black is already not too strong outside it usually seems possible to live small and steal some territory - unless someone can provide some alternative variations for black?
The turn, , is a good play for Black. Not only does it block White in this direction, it threatens a.
There is more detail at 4-4 point 3-3 invasion joseki and the following pages:
mat Very often I ask myself if a 3-3 point invasion still works in the presence of more than one black stone. I've set up a page to discuss which of those work and which don't: 3-3 Point - When Does It Work
BruceWayne You are right normally, but as the description says, if B has a very strong wall such as the marked stones then W will die.