(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]

(;AW[ob][dc][oc][id][me][ne][lh][nh][ph][pn][qn][mo][po]AB[pb][pc][md][qd][pe][lj][nj][pj][qo][cp][qp][nq][pq]C[[Written by Jack Jin, jackjin1988@hotmail.com\]

How to choose the direction of attack?]N[YES_DIRECTIONattack-4.sgf]
(;B[lp]C[The first instinct: making territory while attacking.]
;W[lo]
;B[kp]
;W[ko]
;B[jp]
;W[in]SQ[lj][nj][pj]C[If black gets the bottom territory, the marked group in the centre will become very weak.
On top of that, what black builds at the bottom is only about ten points, it's not that big.])
(;B[kn]SQ[qo][qp][nq][pq]C[Compared to black's group in the center, black's marked group in the corner is much more solid and safe.
Therefore this is the correct direction of play.
]
(;W[lp]
;B[jp]LB[fp:A]C[White's group will survive most likely, but black is helping his center group and also builds the A area.])
(;W[ko]
;B[jo]
;W[kp]
;B[ln]
;W[mq]
;B[np]
;W[no]
;B[jp])))
(;AW[pb][qb][jc][nc][qc][cd][hd][jd][qd][de][hf][jf][cg][ch][ih][jh][ci][gi][hi][gk][gm][hn]AB[ob][ec][kc][oc][pc][kd][nd][pd][ee][ke][pe][ef][qf][hg][dh][fh][hh][di][ii][dj][ij][il][em][dp][pp]C[Which direction should black choose?]N[YES_DIRECTIONattack-5.sgf]
(;B[hp]
;W[jn]SQ[ii][ij][il]C[If black attacks from this direction, again the marked group in the center will become weak.
It looks like black is building the lower side, but it is still open: we can't say it's territory yet.])
(;B[jn]C[Better direction.]
;W[hp]
;B[jp]
;W[fp]
;B[dq]C[Like in the previous problem, black gets the outside and makes white live at a small scale. 
Good for black.]))
(;AW[ea][eb][fb][ob][bc][cc][fc][lc][oc][dd][ed][kd][ld][ie][me][ne][ch][oh][ph][qh][oi][bk][ck][dk][ql][bm][pm][an][cn][dn][pn][bo][fo][go][bp][ep][gp][op][cq][fq][pq][rq][gr][or][qr][rs]AB[fa][ga][gb][pb][gc][jc][kc][pc][cd][gd][md][qd][ce][of][pf][cg][dg][qg][rh][bi][di][pi][qi][cj][rl][qm][rm][co][qo][ap][cp][dp][hp][qp][bq][dq][gq][hq][iq][jq][mq][qq][er][fr][hr][rr]N[YESattack-7.sgf]
;B[]C[This is a position from a professional game. White to play. 

Let's see how white benefits by attacking.]
;W[lb]C[This move looks very slow, but it attacks black's base.
if white wants to attack black, white has to remove the base first.]
;B[he]
;W[id]
;B[hf]
;W[ef]C[Splitting the groups!]
;B[eg]
;W[ff]
;B[ih]
;W[fg]
;B[gh]
;W[fh]
;B[bd]C[Black's left side has become weak and black has to spend a move to protect his group.]
;W[hi]C[The peep is a good move.]
;B[hh]
;W[gi]
;B[ii]
;W[ij]
(;B[ki]
;W[jj]
;B[lg]
;W[hd]
;B[ge]
;W[ib]C[Tasty!]
;B[ng]C[White gets some points at the top, and some potential in the center by the attack.

In the beginning white's attack looked unrealistic, didn't it? BUT LOOK WHAT HE GOT!!!! ;-) hihihi])
(;B[jj]C[Black would ideally like to hane, but white will cut.]
;W[ji]C[Aiaiaiaiaiaiai.]))
(;AW[qb][dc][mc][oc][qc][pd][oe][cf][of][qg][qh][ri][qj][rj][sj][ck][rk][nn][qn][rn][mo][oo][po][lp][iq][lq][kr]AB[fc][hc][kc][rc][qd][pe][qe][pf][og][pg][pi][qi][pj][pk][qk][no][qo][ro][cp][ep][np][pp][gq][mq][pq][lr][mr]N[YESattack-8.sgf]
;B[]C[This attack is all about finding the key point in black's shape.  
Another surprising attack, it's hammer time! (white to play).]
(;W[ni]C[This looks like a keypoint, but it's not.]
;B[oi]C[When black plays the bamboo, white has to spend one more move here.]
;W[nj]
;B[mg]C[So black can escape easily.])
(;W[nj]C[This is the keypoint!]
;B[ni]
;W[mi]
;B[nh]
;W[mj]C[White's outside is much stronger than the previous diagram.]
;B[lg]C[Black still goes out, but white is happy.]))
(;AW[nb][ec][nc][pc][qc][rc][cd][dd][fd][md][ge][me][df][ef][mf][of][mg][bh][fh][ci][gj][ck][on][qn][dp][rp]AB[eb][fb][fc][lc][mc][gd][hd][jd][nd][od][pd][qd][ce][cf][lf][bg][dg][qg][dh][ph][di][ej][pj][jp][np][pp]N[YESattack-10.sgf]
;B[dl]
;W[cl]C[Black is under attack on the left side, but he can regain control. What to do?
Hint: cut when you can!]
;B[gi]C[Although it looks risky, with deep reading, black cuts white!]
;W[fi]
;B[fj]
;W[gk]
;B[hi]
(;W[gg]
;B[fl]
;W[dj]
;B[ei]
;W[gl]
;B[dn]
;W[cm]
;B[ih]C[Now let's evaluate the position:
White has three weak groups (g13, n13 and g8), but black only has one weak group.
Black has gained back control. ])
(;W[el]C[Looks beastly, but black can manage it.]
;B[dm]
;W[dk]
;B[fl]
;W[fk]
;B[ek]
;W[em]
;B[gl]LB[hk:B][en:A]C[Black makes miai of A and B.]))
(;AW[ga][bb][hb][ib][jb][pb][ac][cc][dc][gc][hc][kc][nc][bd][cd][dd][fd][gd][jd][od][be][de][ee][he][bf][cf][ch][fh][ih][bi][fi][hi][pi][bj][ej][pj][gk][pk][qk][cl][dl][hl][dm][hm][dn][hn][co][go][ro][ap][bp][cp][dp][ep][ip][lp][rp][aq][hq][iq][kq][mq][nq][hr][lr][or][pr]AB[ca][ea][ab][cb][db][fb][gb][ob][qb][ec][fc][ic][qc][ad][ed][hd][id][pd][fe][ge][ie][df][ff][if][pf][dg][eg][fg][gg][qh][di][ei][qi][cj][qj][bk][ck][hk][ik][bl][il][cm][im][qm][bn][cn][rn][bo][ho][io][lo][mo][qo][hp][jp][mp][op][qp][bq][cq][dq][fq][gq][oq][pq][rq][ar][cr][qr]C[Sometimes we can overplay when there's a weak group which is not alive.
White to play! ]N[YESattack-11.sgf]
;B[]C[This example comes from a top pro game, it's white's turn.

At the moment black is a little ahead on points, but the big group of black on the left is not alive yet, let's see why.]
(;W[hf]
;B[hg]
;W[an]C[Locally black's group is not 100% alive yet.]
;B[am]
;W[ao]
;B[bm]
;W[ak])
(;W[pg]C[White played here in the game. A normal move. However, white will soon go berserk.]
;B[ph]
;W[of]
;B[pe]
(;W[oh]C[This would be a normal follow up. However, it is too easy for black in this case.]
;B[qg]
;W[og]
;B[kf]C[Black is ahead and it will be hard for white to catch up in the endgame.])
(;W[hf]C[Playing here immediately is good timing!]
;B[hg]C[Black needs to block, it's good timing.]
;W[qg]C[Now we see the 'overplay' of white.
Normally this move is too much, but with black having a weak group, white will welcome the fight!

]
(;B[og]C[This would be risky for black.]
;W[oh]
;B[ng]
;W[rg]
;B[rk]
;W[lg]
;B[ao]C[If black defends his weak group, he will be captured on the right side.]
;W[nh]
;B[nf]
;W[oe]
;B[lf]
;W[mg]
;B[mf]
;W[kf]C[Black has 3 liberties and white has 4.])
(;B[gj]C[In the game black made his group alive immediately.]
;W[hj]
;B[ao]
;W[oh]C[But it gave white points on the right side. The game became close on points again.]
;B[rg]
;W[rf]
;B[qf]
;W[og]
;B[rh]
;W[oc]
;B[pc]
;W[nb]
;B[pa]
;W[rj]C[A close game!]))
(;W[qg]C[This would be too eager. The timing is off.]
;B[og]
;W[oh]
;B[ng]
;W[lg]
;B[nh]
;W[hf]SQ[ic][hd][id][ie][if]C[When white plays here now, black can sacrifice the marked stones.]
;B[am]LB[ie:A]SQ[pg][qg][pi][pj][pk][qk]C[Black has gained on the right side, so he can sacrifice A.]))))
