(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[백 Cho Hye Yeon 9p]PB[badukmovies]
(;AW[el][cm][cn][en][bo][fo][bp][cp][cq][eq][gq][er]AB[dj][fj][bk][cl][bm][bn][co][do][dp][bq][dq][dr]
;W[es]C[Today's topic - descent tesuji.
]
(;B[cr]
;W[br]
(;B[aq]
;W[ar]
;B[bs]
;W[ap]
;B[cs]
;W[dn]
;B[as]
;W[eo]C[Black loses a race to capture.
])
(;B[bs]
(;W[ar]C[This is what black wants, but...
]
;B[ao]
;W[aq]
;B[an]
;W[ap]
;B[cs])
(;W[aq]C[White should capture one stone.
]
(;B[ao]
;W[cs]
;B[ds]
;W[dn]
;B[an]
;W[ap]
;B[ar]C[This is ko!
]
;W[as])
(;B[ar]C[Ko is not enough for black.
])))
(;B[ar]
;W[aq]
;B[bs]
;W[as]C[This is not good for black.
]))
(;B[br]C[This is the right move.
]
;W[cr]
(;B[cs]C[However, this move is a hallucination.
]
(;W[ds]
;B[bs]C[Black wants this sequence, but...
])
(;W[bs]C[This is white's resistance!
]
;B[as]
;W[ds]C[Black cannot avoid a ko-fight.
]))
(;B[bs]C[This move is tranquil.
]
;W[cs]
;B[ds]C[White is dead!
])))
(;AW[dm][en][bo][co][do][ap][bp][ep][eq][ar][er]AB[eo][fo][cp][dp][fp][aq][bq][dq][fq][hq][cr]C[Black to play and live!]
(;B[dr]C[Wrong.]
;W[br]C[Black's failure.
])
(;B[bs]C[Wrong.]
;W[dr]
;B[cq]
;W[cs]
;B[ds]
;W[es]C[A ko for the corner.])
(;B[br]C[Wrong, ko again.]
;W[dr]
;B[cq]
;W[bs]C[White is happy!
])
(;B[cs]C[This move is a descent tesuji.
]
(;W[br]
;B[cq]
;W[ds]
;B[fr]C[White is dead due to double self-atari.
])
(;W[dr]
;B[cq]
;W[bs]
;B[fr])))
(;B[cp]C[Here we start with a joseki.]
;W[ep]
;B[gq]
;W[cq]
;B[dq]
;W[dp]
;B[eq]
;W[fq]
;B[fp]
;W[fr]
;B[cr]
;W[bq]
;B[er]
;W[es]
;B[dr]
;W[gr]C[This starts a joseki for which white needs the ladder.]
;B[co]
;W[dn]
;B[br]
;W[hq]
;B[gp]
;W[hp]
;B[gn]
;W[do]
;B[ho]
;W[cn]
(;B[jp]C[Tricky move by black. White to play!
]
(;W[bo]C[Black wants white to play in this way.
And then...
]
;B[aq]
;W[bp]
;B[ir]
;W[hr]
;B[iq]
(;W[ds]
;B[cs]
;W[fs]
;B[ip]C[White is dead!
])
(;W[fs]
;B[ip]
;W[ar]
;B[as]))
(;W[aq]C[This is the descent tesuji!
]
(;B[ar]
;W[bo]
;B[ir]
;W[hr]
;B[iq]
;W[fs]
;B[ip]
;W[ds]
;B[hs]
;W[cs]C[White wins a race to capture!
])
(;B[bo]
;W[ar]
;B[ap]
;W[bn]C[Black is suffocated!
]
;B[bs]
;W[ds]
;B[ir]
;W[hr]
;B[iq]
;W[fs]C[Black is dead!
]))
(;W[ap]C[This is a false tesuji at this point.
]
;B[ar]
;W[bo]
;B[ir]
;W[hr]
;B[iq]C[White is dead.
]))
(;B[bp]C[Black should capture two white stones.
]
;W[bo]
;B[aq]
;W[jp]
;B[io]
;W[lq]
;B[dk]
;W[el]C[This is the variation of jeongseok.
]))
(;AW[em][en][gn][do][go][dp][hp][dq][fq][gq][br][cr][dr][hr]AB[dl][dm][dn][bo][co][eo][fo][ep][bq][eq][hq][iq][er][ir]C[Black to play. ]
(;B[es]C[This is a false tesuji.
]
;W[fr]
;B[ar]
;W[fs]C[Black is dead!
])
(;B[fs]C[If black plays here...
]
;W[gr]
;B[ar]
;W[fn]
;B[cp]
;W[fr]C[Black loses a race to capture.
])
(;B[hs]C[This is the first move. And then...
]
(;W[fs]
;B[fr]
;W[gr]
;B[es]C[Black connects with the influence and white in the corner is dead.
])
(;W[gr]C[White has no choice but to connect, and then...
]
;B[es]C[This is a descent tesuji!
]
;W[gs]C[White should block.
]
;B[ar]
;W[fn]
;B[ds]
;W[fp]
(;B[bs]C[This is a terrible mistake.
]
;W[cs]
;B[cp]
;W[as]
;B[sg]C[Ko!
])
(;B[cp]C[Black should fill the outside liberty!
]
;W[fr]
;B[bs]C[White is dead!
]))))
(;AW[oc][pc][qc][qd][re]AB[pb][lc][nc][nd][rd][oe][qe][qf][qh]C[Black to play - a life & death problem.
]
(;B[ob]
;W[sd]
;B[rf]
;W[rc]
;B[ra]
;W[rb]
;B[sb]
;W[qa]
;B[qb]
;W[sa]C[Black cannot avoid a ko-fight.
])
(;B[sd]C[This is a descent tesuji!
]
(;W[ob]
;B[sb]
;W[rb]
;B[rf]C[White cannot live.
])
(;W[rc]
;B[ob]
;W[sc]
;B[qb]
;W[rb]
;B[ra]
;W[qa]
;B[sa]C[Black kills white!
])))
(;AW[na][pa][mb][ob][mc][pc][qc][md][od][me][mf][og][pg][rg][sg][qh]AB[nb][nc][nd][pd][qd][rd][ne][oe][pe][pf][rf]C[Black to play 
]
;B[oc]
;W[qf]C[At this point! Where can black play?
]
(;B[rc]
;W[rb]
;B[qb]
;W[pb]
;B[ra]
;W[qa]
;B[sb]
;W[sa]C[Black cannot avoid a ko-fight.
Black's failure.
])
(;B[sd]C[The descent tesuji!
]
(;W[rc]
;B[sf]
;W[re]
;B[se]C[Black is alive!
])
(;W[re]
;B[rb]C[And then...
]
;W[rc]
;B[qb]
;W[pb]
(;B[sb]C[The second descent tesuji!
]
;W[qa]
;B[ra]C[Black is alive!
])
(;B[sc]C[This move is a terrible blunder.
]
;W[sb]
;B[sa]
;W[qa]C[Black is dead!
])))))
