(;FF[4]ST[2]RU[Japanese]AB[qp][iq][nq][pq][ab][bb][pb][bc][cc][pc][ad][cd][qd][be]
[ge][pe][cf][df][ef][ff][hf][if][of][fg][gg][hh][ph][di][ei][gi][hi][pi][fj][hj]
[ck][fk][cl][gl][cm][dm][fm][gn][do][qo][cp][fp]AW[en][pn][qn][po][ba][cb][db][ob]
[dc][oc][dd][gd][hd][jd][ce][de][fe][je][ne][bf][jf][nf][bg][hg][ig][qg][ch][gh]
[ih][qh][ci][qi][cj][dj][ej][gj][qj][bk][dk][ek][dl][el][fl][am][em]PL[B]CR[jn]
[kn][jo][ko][jp][kp]TR[gn]C[This game was played in the Chinese league.  I was watching it on Tygem.  White is one of the top Korean pros in the Chinese league (and has won world championships before), and black is near the top of the Chinese ratings, so this game is between top level players.

Players above double digit kyu will be familiar with the double hane as a powerful shape.  More rare is the 3 step hane. For this to be good, white needs to be ready to give away one stone as not important (usually a ponnuki in a direction which is not so useful).  But I hadn't imagined a 5 step hane.

The sequence starts here.  Black has just played triangle. This activates a lot of black potential around the circled area, and white wants to minimize what black can get here.]
AP[GoGui:1.4.0]CA[UTF-8]PB[Tan Xiao (7P)]PW[Choi Cheolhan (9P)]KM[0]MULTIGOGM[1]
;W[ip]C[White chooses an attachment, typically a good idea for defence in the opponent's area of influence.]
;B[jp]TR[gl][fm][gn][fp]C[This hane resists as strongly as possible, and tries to push white towards black's triangle wall.]
;W[hq];B[hp];W[io];B[gq]TR[ph][pi]LB[jq:A][kp:B]C[Black can choose this way, as the triangled stones break the ladder that follows after A & B.]
;W[jq];B[hr];W[ir];B[hq]C[Black does not have the ko threats to resist, and this ko would be much heavier for black than for white.]
;W[kp]C[White starts the ladder, even though it is not working!  What is the plan?]
;B[jo];W[pf]C[Ah, a ladder breaker...];B[ko]TR[kp]LB[mo:B][jn:A]C[Black needs to break the ladder.  Often A is good shape for coming out, as it gets an extra liberty.  But this move puts more pressure on the stones around triangle, and if black can play B they will make many points at the bottom.]
;W[oe]C[White uses their ladder breaker to cut black.];B[qf];W[pg];B[oa]C[As the corner is now surrounded, white q19 will be absolute sente for white, so black must take this point now before white can get it.]
;W[na];B[pa];W[nb];B[rf]C[Black completes his corner, so white gets sente.];W[lo]
TR[jo][ko][jp]LB[lp:A]C[And now time for the magic of the 5 step hane!  Here is step 4.  This move makes the triangled stones short of liberties.  The cut at A now looks scary.  But... (see varation).]
(;B[ln]CR[nh][oh][ni][oi][nj][oj][pj][nk][ok][pk]TR[ik][jk][il][jl][kl][im][jm]
[km][in][jn]C[So black plays in the center.  Black gains potental in the triangled area and works to reduce what white may gain in the circled area. ]
;W[mn]LB[lp:B][mo:A]C[And white plays another hane. Wow!  Can't black punish all these weak points?  How about the cuts at A or B? See variations if black chooses these.  A is complex.  White has to read very carefully to see this doesn't work for black, otherwise they cannot chose this move.]
(;B[lm]LB[kp:B][lp:C][mo:A]C[So, since A & B don't work well, black just plays calmly in the center.]
;W[mo]LB[lq:A]C[Finally white fixes one of the cut points.  Later black can play A to take the points at the bottom.  And black has sente.  White's sequence has worked, but black is still fine and went on to win this game by 4.5 points.])
(;B[mo];W[lp]TR[kn]LB[km:A][lm:B]C[After cutting, black must defend the double atari at triangle. A is the normal shape for this, but white needs to be sure they have thought about triangle or B (see variations for triangle and B).  When involved in close fighting & life and death, you have to watch out for checking only the good shape move. B is very tricky, but ultimately it still doesn't work for black.]
(;B[km]LB[mp:A][np:B]C[White can think about A & B.  It seems B doesn't work so well (see variation), so A is white's plan.  How does it work out?]
(;W[mp]TR[mo]C[Can they capture the key triangled stone?];B[no];W[np];B[op];W[oo]
;B[nn];W[mm]CR[lo][kp][lp][mp][np]TR[nn][mo][no]LB[kq:A][lq:B][mq:C]C[It's going to be a capturing race between the triangled stones and the circled stones.  How many liberties do the circled stones have?  It seems three, but what happens if black tries to take a liberty at A, B, or C?  See variations.  After looking at the variations you will see white has 4 liberties always.  So black must make 4 liberties in sente with the triangled stones (follow the main line here), and it turns out he cannot do it.]
(;B[nm];W[lm];B[kn]LB[kl:A][nl:B]C[Can white force at A now?  See variation.  It seem actually they can do this, but anyway B right away is good enough.]
(;W[nl]LB[om:A][ml:B]C[Black can consider A or B.]
(;B[ml];W[ll];B[ol];W[mk]LB[kl:B][nk:A]C[Black cannot play the ko now at A, as white has local threats at B, and this ko is too large. Only local threats would do.]
;B[om];W[ok]LB[pl:A][ql:B]C[Now black can try A or B.  A is fairly easy to refute, but how about B?]
(;B[ql]LB[pl:B][rl:A]C[If white plays A, black can connect at B and get 5 liberties, too many!.  So white can only play B.]
;W[pl];B[pm]LB[qm:B][rl:C][pk:A]C[Can white connect at A?  No! Black will get too many liberties after connecting at B.  So white can think about B or C.]
(;W[qm];B[pk];W[pj];B[rl];W[qk]C[Black doesn't have enough threats to imagine ko now..]
;B[pl];W[rm]C[And black only has 3 liberties. White is ok.])
(;W[rl];B[pk];W[pj];B[rm];W[qm];B[rk];W[qk]C[It seems that white can also play this way as black cannot connect and doesn't have ko threats.])
(;W[pk];B[qm];W[rm];B[rl];W[rn]C[Black has sente and 4 liberties, too much.]))
(;B[pl];W[ql];B[pk];W[pj];B[qk];W[rk];B[rl];W[pm];B[qm];W[on];B[ql];W[sl]C[And black is dead.]))
(;B[om];W[kl];B[in];W[ol];B[pm];W[ql]C[And net is simple.  Black can do nothing.]))
(;W[kl]LB[ll:A]C[What if black cuts at A? ];B[ll];W[ml];B[nl];W[mk];B[in];W[nk]
;B[pl];W[ol];B[om];W[ok];B[pm];W[ql]
(;B[qm];W[rm];B[rl];W[pk];B[qk];W[on]C[It seems white can play this way.])
(;B[pk];W[pj];B[qm];W[rm];B[rl];W[qk])))
(;B[kq];W[lq];B[jr];W[lr]C[White has 4.])
(;B[mq];W[kq];B[lq];W[lr]LB[ks:A][mr:B]C[Black can try A or B now. As it turns out, white still gets 3 liberties left either way (with sente), so it counts as 4 originally.]
(;B[mr]LB[jr:A][kr:B]C[After cutting at A or B, black will need a turn to capture.])
(;B[ks];W[kr];B[mr];W[js];B[hs]C[White has 3 with sente, so originally 4.])))
(;W[np]LB[mp:A]C[This looks like a good move for white, but actually after black A, I cannot find a good sequence for white.  It seems white will die.  Please look yourself.]
;B[mp];W[mq];B[no]
(;W[lr];B[mr];W[lq];B[nr];W[op];B[nn];W[mm];B[kr])
(;W[nr];B[op])))
(;B[kn];W[mp];B[no];W[np];B[op];W[oo];B[nn];W[mm];B[nm];W[nl];B[ml];W[lm];B[om]
;W[km];B[jn];W[jm];B[in]TR[nm][om][nn][mo][no]C[And white has 4 liberties with the center stones, so he can proceed to capture the triangled stones like the main line.])
(;B[lm]C[This is very complicated.];W[mp];B[no];W[np];B[op];W[oo];B[nn];W[mm];B[nm]
;W[ml];B[nl]LB[jn:A][ll:B]C[The next move, white has to be very careful.  It may seem good to squeeze with A and then the moves after B, but white will regret it (see variation).]
(;W[nk]LB[ol:A][pl:B]C[Now black might try A or B. ]
(;B[ol]LB[pl:A]C[This is the hardest move for white to handle. A is actually simpler (see variation).]
;W[pl]C[White must play here to restrict black's liberties.];B[ok];W[oj]
(;B[nj];W[mk];B[pj];W[kn]LB[jn:A]C[Cut is natural now, although it seems A is also possible.  Now white is very glad they didn't lose the option of going after these stones.]
;B[jn];W[jm];B[in];W[km];B[ll];W[im];B[hn];W[lk];B[kl];W[jk]C[And white wins.])
(;B[mk];W[ll]C[This is still sente.];B[kn];W[nj];B[kl];W[lk];B[pk];W[qk]
(;B[kk];W[lj];B[pj];W[oi];B[oh];W[nh])
(;B[pj]C[Now white should force to gain a liberty in the center.]
(;W[jn];B[km];W[kk];B[in];W[oi];B[oh];W[nh];B[mj];W[ni]C[Black can go no further.])
(;W[oi]C[If white just plays here...];B[oh];W[nh];B[mj];W[ni];B[lj]LB[jn:A][km:B]
[kk:C]C[Oops, white forgot to force with A, B, C, and now black can capture white in a ladder.])))
(;B[pk];W[qk]TR[lm][ln]LB[mk:B][nj:A][pj:C]C[The crucial point here is black cannot play at A, as white B is sente against the triangled stones. And if black just plays C...]
(;B[pj];W[mk]LB[kn:B][oi:A]C[Now white makes miai of A (capturing the large chain) and B (eventually capturing two stones).]
(;B[ni]C[If black helps these stones...];W[kn];B[jn];W[jm];B[in];W[km];B[ll];W[kk])
(;B[ll];W[oi];B[oh];W[nh]C[Black cannot capture anything or gain more liberties, so he is lost.
]
;B[ni];W[nj];B[mi];W[lk];B[in]))
(;B[nj];W[mk];B[pj];W[kn];B[jn];W[jm];B[in];W[km];B[ll];W[im];B[hn];W[lk];B[kl]
;W[jk])))
(;B[pl];W[jn];B[kn];W[ll];B[km];W[kl];B[jm];W[jl];B[im];W[ol];B[om]
(;W[pm];B[ok])
(;W[ok];B[pm];W[ql]C[And black is caught.])))
(;W[jn];B[kn];W[ll];B[km];W[kl];B[jm];W[jl];B[im];W[nk];B[ol]LB[pl:A]C[To restrict black's liberties white needs to play A now, but it doesn't work.]
(;W[pl];B[ok]
(;W[oj];B[nj]C[If white hadn't played out the forcing moves, black couldn't play this move.]
;W[mk];B[pj];W[oi];B[oh];W[ni];B[nh];W[mi];B[pk]C[This way black has gotten 6 liberties. Game over.])
(;W[nj];B[oj];W[oi];B[oh];W[ni];B[pj]C[Black has gotten 5 liberties. White is lost.]))
(;W[ok];B[pl]TR[lo][kp][lp][mp][np]C[Black has gotten 5 liberties. White triangled stones have died.]
;W[ql]))))
(;B[lp]C[This move does "work".  However...];W[mo];B[kq]TR[nk]C[Black should take to eliminate further forcing moves.  Black has now secured the bottom territory.  ]
;W[lm]TR[nj][oj][pj][nk][ok][pk][nl][ol][pl][om][pm][on]C[But white can play here.  This will give white lots of potental around triangle, and black's potential in the center is mostly gone.  White's gain in the center is worth more than black's capture of territory at the bottom.]))
(;B[lp];W[mp];B[kq]C[Black should take to reduce further forcing moves.];W[ln]CR[oh]
[oi][pi][oj][pj][nk][ok][pk][nl][ol][pl]TR[il][jl][im][jm][in][jn]LB[ln:A]C[This way black's potential around triangle is reduced, and white can get a lot around the circled points.  And the bottom is not even sealed yet!  Not good for black.]))