This problem is quite difficult. If you think you can handle it, you can play without hints [N]; otherwise, choose [S]ome hints to make it only somewhat difficult, or [L]ots of hints for a guided tour. :)
If you aren't sure what to do, I recommend [L].
N.B. There aren't many wrong variations included on the [S] path; you can navigate the other paths for more details.
(;AB[ab]AB[ba]AB[cc]AB[cd]AB[dd]AB[ed]AB[ec]AB[fb]AW[db]AW[af]AW[be]AW[bf]AW[ce]AW[de]AW[ee]AW[fd]AW[fc]AW[gc]AW[gb]AW[ga]AW[gf]C[Would you like (N)o hints, (S)ome hints, or (L)ots of hints?FORCE]LB[ch:N]LB[eh:S]LB[gh:L]AP[goproblems]
(;W[ch];B[eh]C[Ok, good luck!]
(;W[eb];B[cb])
(;W[bd];B[bc])
(;W[bc];B[bb])
(;W[ac];B[cb])
(;W[fa];B[cb])
(;W[ea];B[cb])
(;W[cb];B[eb]
(;W[bb];B[bc]
(;W[fa];B[da])
(;W[ea];B[fa])
(;W[da];B[ea])
(;W[ca];B[fa]
(;W[da];B[ac]C[Tough ko fight for white!])
(;W[ad];B[ac])
(;W[aa];B[ac]C[You made a hard ko fight one step harder ... :(])))
(;W[bd];B[bc])
(;W[bc];B[bb])
(;W[da];B[bc])
(;W[ca];B[bb])
(;W[ea];B[fa])
(;W[fa];B[ea]
(;W[ca];B[bb])
(;W[bd];B[bc])
(;W[bc];B[bb])
(;W[bb];B[bc]
(;W[ca];B[da]C[You made the ko fight harder than it should be.])
(;W[ac];B[ad]C[You made the ko fight harder than it should be.])
(;W[ad];B[ac]
(;W[bd];B[da])
(;W[ca];B[bd]
(;W[aa];B[ae]C[You made the ko fight harder than it should be. :(])
(;W[ae]C[Good work! :) It's now a tricky situation: either player can start the ko, but at the penalty of the other side capturing first.RIGHT])))))))
(;W[eh];B[ch]C[Ok. E18 looks tempting, but it's not the right move. Look towards the corner instead.];W[cb];B[eb]C[Good. Now threaten to connect to one of your outer groups.];W[fa];B[ea];W[bb];B[bc]C[At some point, you'll want to play C19. Not now though. :)];W[ad];B[ac]C[getting close ...];W[ca];B[bd]C[Now, A19 or A15? One makes it messy; the other keeps it simple ...];W[ae]C[Good work! :)RIGHT])
(;W[gh];B[eh]C[Ok. The two stones in the corner are very close to making two eyes. Prevent this, and keep your own stones connected.]TR[ab]TR[ba]
(;W[cb];B[eb]C[Good. Now reduce black's space by threatening to connect to G19. Stay solid ...]TR[db]TR[ga]
(;W[fa];B[ea]C[Now attack the corner -- make it hard for black to unite his stones. Conversely, don't let your own stones get cut.]
(;W[bb];B[bc]TR[bb]TR[be]C[Threaten to connect to B15; this will again reduce black's liberties.]
(;W[ad];B[ac]C[Good work so far. :) Now, time to fill up the eyespace and get a ko fight started.]
(;W[ca];B[bd]C[A19 makes things messy, since black will just fight the other ko at A15. Don't make things messy.]
(;W[ae]C[Well done! :)RIGHT])
(;W[aa];B[ae]C[You made things messy. :(]))
(;W[da]C[This is not great. It makes a seki, and is gote. The good shape move is C19, which also attacks B19.])
(;W[dc]C[This is not great. It makes a seki, and is gote. The good shape move is C19, which also attacks B19.]))
(;W[bd];B[da]C[Doesn't threaten to connect.])
(;W[ac];B[ad]C[Well, that threatened to connect, but it makes the ko fight harder for you. The goal was just to reduce black's liberties.]))
(;W[bc];B[bb]C[You were too aggressive in separating black's stones.]))
(;W[da];B[bc]C[That doesn't threaten to connect.])
(;W[ea];B[fa]C[That threatened to connect, but now white loses time saving E19. You can't afford to give black sente.]))
(;W[bc];B[bb]C[Black can easily keep the white stones separated.])
(;W[eb];B[cb]C[Black will happily sacrifice F18 to save the rest of the group.])))