(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[Baduk]PB[Movies]
;B[pd]
(;W[qc]C[Today we would like to give you some insights into the main weakness of a hoshi-stone: the san-san point. 
Invading a hoshi stone on san-san is usually done when the opponent already has other stones around.])
(;W[dp]
;B[qp]
;W[dd]
;B[oq]
;W[qj]
;B[fc]
;W[cf]
;B[qh]
;W[ec]
;B[jd]
;W[fd]
;B[ql]
;W[fq]
;B[jp]
;W[oj]
;B[ol]
;W[mj]
;B[oh]C[This is the position of a professional game between Hu Yaoyu and Wang Lu played in 2009. Black just played P12 and is building a framework at the top. You are white (Wang Lu) and about to make your move. Where would you play?


]
(;W[qc]LB[jd:1][pd:A][qh:2]C[The move played in the game. 

So how do you know when to simply approach a hoshi stone, and when to invade on 3-3? 
As a rule of thumb you invade on san-san when your opponent has a double wing formation from his hoshi (black 1 and 2). ])
(;W[nc]C[Wrong. ]
;B[pc]
;W[lc]C[White makes a small group at the top, but he has another weak group in the centre.
Black will try to split them and attack them simultaneously.]))
(;AB[jd][pj]C[This is the perfect example of a double wing formation. ]
;W[qc]C[When your opponent has this kind of formation, be sure to play severe and strike at the centre, the san-san!

]
;B[pc]C[Let's have a look at the following standard pattern.]
;W[qd]
;B[qe]
;W[re]
;B[qf]
;W[rf]
;B[qg]
;W[pb]
;B[ob]
;W[qb]
;B[nc]LB[jd:1][pj:2]C[White takes the corner in sente. 

Note the positions of the stones at 1 and 2. 
These two stones originally formed the double wing formation of black. Is black still happy with their placement?
])
(;AB[jd]
;W[qc]SQ[jd]C[When white invades and black has only one high wing stretching from his hoshi (the marked stone), black won't hesitate. ]
;B[pc]C[Black has no other choice and blocks from this side.]
;W[qd]
(;B[qe]
;W[re]LB[pj:A]C[Black can choose to play:

1. Goes back to the sente joseki for white (but now better for black than before because of the absence of A.

2. Aims at taking the corner or to close white in.

3. Special tesuji which needs a favourable ladder for black. ]
(;B[qf]
;W[rf]
;B[qg]
;W[pb]
;B[ob]
;W[qb]
;B[nc]LB[pj:A]C[Like this we return to the same joseki position. White still has sente.

The main difference for black is the absence of a stone at A! 
This result is better for black than when there already is a stone at A. ]
;W[cp]C[If white would play tenuki..]
(;B[pj]C[..would you still play here as black, like in the double wing formation?])
(;B[pk]C[Black could also choose to play further away from his strength. ])
(;B[jj]C[Or maybe you would like to try other huge scale plans?])
(;B[pq]C[Or what about simply leave the incredibly strong group at the top for what it is?]))
(;B[rf]C[White has two possible responses:
Going for the right side with 1, or starting a strong counter attack and aiming for the top with 2.
3 is submissive.
]
(;W[qf]
;B[pe]
;W[rg]
;B[rd]
;W[sf]
;B[rc]LB[lc:A]C[This result is locally even. White gets a ponnuki shape on the outside and keeps sente.
Black gets a very big corner, but the two white captured stones still have a lot of aji. 
This aji makes it easier for white to invade at the top, around A. ]
;W[qb]
;B[rb]LB[nb:A]C[This leaves a lot of aji moves on the top side.
Even if white doesn't get the opportunity to use the aji around A, this exchange still leaves him some benefits in the corner.]
;W[sd]C[This hane for white is big endgame. 
What is the correct answer for black? ]
(;B[pb]C[Wrong. ]
;W[sb]C[This gives white the opportunity to play the clamp in the late stage of endgame. ])
(;B[sb]C[The correct move.]))
(;W[pb]
;B[ob]
(;W[oc]LB[jc:B][jd:A]C[A powerful tesuji. 

Black 1 is the proper move.
2 is a special tactic, but with a high stone at A it's usually wrong. If that stone would be at B, it's a completely different story (will be in episode #12). ]
(;B[pe]
;W[nb]C[Another trade is the result. ]
;B[qb]
;W[oa]
;B[rb]C[Black takes the corner, and white is happy with the top.]
;W[lc])
(;B[od]
;W[qb]
(;B[pf]
;W[nc]LB[jd:A]C[Because black A is high, this is a very dangerous tactic for black. ]
;B[nb]
;W[mc]
;B[mb]
;W[lc]
;B[lb]
;W[kc]LB[qb:A]C[Blacks stones on the second line are isolated, but whites stones at A are not alive yet either: a very complicated fight. ])
(;B[rd]C[Wrong. Black collapses.]
;W[nc]
;B[nb]
;W[pe]
;B[qf]
;W[mc]LB[mb:A][oe:B]C[A and B will become miai for white. ]
;B[mb]
;W[lc]
(;B[lb]
;W[oe]
;B[nd]
;W[me])
(;B[oe]
;W[lb]
;B[rc]
;W[rb]
;B[sb]
;W[ma]))))
(;W[qf]C[Wrong. it's too late for this atari. ]
;B[pe]
;W[rg]
;B[rd]
;W[sf]
;B[rc]LB[ob:2][pb:1]C[The exchange of white 1 for black 2 is very good for black: white destroyed the aji. ]))
(;W[rd]C[Mistake. ]
;B[qf]
;W[pb]
;B[ob]
;W[qb]
;B[nc]C[White can live, but is completely framed in. Black has superior strength. ]))
(;B[rd]C[An interesting probe. 
Black needs a favourable ladder for this to work best.

If white has the ladder, he can extend on the second line at 1. 
If black has the ladder, white can play easy at 2 or more active at 3. 



]
(;W[rf]
(;B[rc]C[The ladder variation.]
;W[qb]
;B[rb]
;W[pb]
;B[ob]
;W[pe]
;B[qf]
;W[oc]
;B[od]
;W[qg]
;B[pf]
;W[oe]
;B[nd]
;W[of])
(;B[qb]C[If white has the ladder, this is the best black can do. ]
;W[rc]
;B[rb]
;W[sd]C[Slightly better for white. ]))
(;W[rc]LB[rf:A]
;B[rf]
;W[sd]
;B[qf]LB[pb:A]C[Black seals white in completely. 
White however has sente.

A is big endgame sente for black.]
;W[dp]
;B[pb]
;W[cn]
(;B[rb]C[If white does not respond, black can make a big ko in the corner. ]
;W[qb]
;B[qa]
;W[ra]
;B[sa]
;W[sb]
;B[sc]C[Black can take this ko first, so white has to find the first ko threat!])
(;B[ra]C[Wrong!]
;W[rb]
;B[sb]
;W[qa]
;B[qb]C[This is also a ko, but here white can take first. ]
;W[sa]))
(;W[pb]
;B[qb]
;W[rc]
;B[ob]
;W[qf]
;B[pe]
;W[rg]C[See the bonus tab for some fun games with this variation. ])))
(;B[qf]C[Will be discussed in episode #12.])
(;B[qb]C[Will be discussed in episode #12.])))
