invalid problem set
Problem 4256
Created 2004-04-14
Source KGS game
Rating
Difficulty 0.6 kyu
Average Solve Time 79 secs
User Attempts
720 / 3352
Solve Ratio Rating 2 kyu
rating history
This is based on a game of mine in KGS. White played 1 and I answered 2. After that I thought white could kill me with 3 and I was ready to resign. However, white did not play 3, so I gratefully played it myself. However, I was wrong: White 3 does not kill anything. Prove it.
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[White]PB[Black]AW[di][aj][bj][cj][ak][dk][ek][fk][al][bl][fl][fm][gn][co][fo][ho][jo][dp][ep][fp][gp][aq][cq][br]AB[bk][ck][cl][dl][el][am][bm][em][cn][en][fn][ao][bp][bq][eq][fq][gq][hq][jq][kq]LB[ao:2][co:3][aq:1]C[Black to play and save all his stones.]
(;B[bo]CR[bo]
;W[dn]CR[dn]
(;B[cp]CR[cp]
;W[do]CR[do]
(;B[cr]CR[cr]
;W[cm]CR[cm]
(;B[dm]CR[dm]
;W[eo]CR[eo]
(;B[cm]CR[cm]
;W[an]CR[an]
(;B[bn]CR[bn]
;W[dq]CR[dq]
(;B[dr]CR[dr]
;W[ar]CR[ar]
(;B[bs]CR[bs]C[RIGHT])
(;B[as]CR[as]
;W[bs]CR[bs]
;B[cs]CR[cs]
;W[er]CR[er])
(;B[er]CR[er]
;W[ap]CR[ap]))
(;B[bs]CR[bs]
;W[ar]CR[ar]
(;B[dr]CR[dr]C[RIGHT])
(;B[cs]CR[cs]
;W[dr]CR[dr])
(;B[as]CR[as]
;W[cs]CR[cs]
(;B[dr]CR[dr]
;W[ap]CR[ap])
(;B[bs]CR[bs]
;W[dr]CR[dr]))
(;B[ds]CR[ds]
;W[dr]CR[dr]
(;B[cs]CR[cs]
;W[es]CR[es])
(;B[er]CR[er]
;W[cs]CR[cs]))
(;B[er]CR[er]
;W[dr]CR[dr])))
(;B[dq]CR[dq]
;W[bn]CR[bn]))
(;B[dq]CR[dq]
;W[cm]CR[cm]))
(;B[dq]CR[dq]
;W[dm]CR[dm])
(;B[bn]CR[bn]
;W[dm]CR[dm]))
(;B[dq]CR[dq]
;W[cm]CR[cm]
(;B[cr]CR[cr]
;W[dm]CR[dm])
(;B[dm]CR[dm]
;W[eo]CR[eo]
(;B[cr]CR[cr]
;W[cm]CR[cm])
(;B[cm]CR[cm]
;W[an]CR[an]
(;B[cr]CR[cr]
;W[bn]CR[bn])
(;B[bn]CR[bn]
;W[cr]CR[cr]
(;B[ar]CR[ar]
;W[dr]CR[dr]
(;B[er]CR[er]
;W[as]CR[as]
(;B[ds]CR[ds]
;W[cs]CR[cs]C[Seki is not good enough])
(;B[cs]CR[cs]
;W[ds]CR[ds]
;B[es]CR[es]C[Seki is not good enough.])
(;B[es]CR[es]
;W[ar]CR[ar])
(;B[bs]CR[bs]
;W[cs]CR[cs]
;B[es]CR[es]
;W[ar]CR[ar]
;B[ds]CR[ds]C[Seki is not good enough.]))
(;B[ap]CR[ap]
;W[bs]CR[bs]
;B[er]CR[er]
;W[ds]CR[ds]
;B[es]CR[es]C[Seki is not good enough.])
(;B[bs]CR[bs]
;W[cs]CR[cs]
(;B[er]CR[er]
;W[as]CR[as]
;B[es]CR[es]
;W[ar]CR[ar]
;B[ds]CR[ds]C[Seki is not good enough.])
(;B[ap]CR[ap]
;W[as]CR[as]
;B[er]CR[er]
;W[aq]CR[aq]C[Two-step ko])))
(;B[dr]CR[dr]
;W[ar]CR[ar])))))
(;B[dr]CR[dr]
;W[cr]CR[cr]
;B[dq]CR[dq]
;W[ar]CR[ar]))
(;B[dm]CR[dm]
;W[do]CR[do]
(;B[cp]CR[cp]
;W[dq]CR[dq])
(;B[dq]CR[dq]
;W[cp]CR[cp]))
(;B[dq]CR[dq]
;W[cp]CR[cp])
(;B[cm]CR[cm]
;W[cp]CR[cp])
(;B[eo]CR[eo]
;W[do]CR[do]))
(;B[cp]CR[cp]
;W[bo]CR[bo])
(;B[ap]CR[ap]
;W[cp]CR[cp]
(;B[bo]CR[bo]
;W[dn]CR[dn])
(;B[ar]CR[ar]
;W[cr]CR[cr]
(;B[bo]CR[bo]
;W[dn]CR[dn])
(;B[dn]CR[dn]
;W[bo]CR[bo])
(;B[do]CR[do]
;W[bo]CR[bo]))
(;B[do]CR[do]
;W[bo]CR[bo])
(;B[dn]CR[dn]
;W[bo]CR[bo])
(;B[bn]CR[bn]
;W[bo]CR[bo]))
(;B[do]CR[do]
;W[bo]CR[bo]
(;B[cp]CR[cp]
;W[ap]CR[ap])
(;B[bn]CR[bn]
;W[cp]CR[cp])
(;B[eo]CR[eo]
;W[cp]CR[cp]
(;B[bn]CR[bn]
;W[dm]CR[dm])
(;B[dm]CR[dm]
;W[bn]CR[bn]))
(;B[dq]CR[dq]
;W[cp]CR[cp])
(;B[ap]CR[ap]
;W[cp]CR[cp])
(;B[dm]CR[dm]
;W[cp]CR[cp]))
(;B[dn]CR[dn]
;W[bo]CR[bo])
(;B[dq]CR[dq]
;W[cp]CR[cp])
(;B[cr]CR[cr]
;W[bo]CR[bo]
(;B[bs]CR[bs]
;W[cm]CR[cm]
(;B[dm]CR[dm]
;W[dn]CR[dn]
(;B[do]CR[do]
;W[eo]CR[eo]
(;B[an]CR[an]
;W[dn]CR[dn]
(;B[cm]CR[cm]
;W[bn]CR[bn]C[Ko])
(;B[bn]CR[bn]
;W[cm]CR[cm])
(;B[ap]CR[ap]
;W[cm]CR[cm])
(;B[ar]CR[ar]
;W[cm]CR[cm]))
(;B[cm]CR[cm]
;W[bn]CR[bn]
(;B[an]CR[an]
;W[dn]CR[dn]C[Ko])
(;B[dn]CR[dn]
;W[an]CR[an])
(;B[ap]CR[ap]
;W[dn]CR[dn]C[Ko])
(;B[ar]CR[ar]
;W[dn]CR[dn]C[Ko]))
(;B[bn]CR[bn]
;W[dn]CR[dn]C[Ko])
(;B[dn]CR[dn]
;W[bn]CR[bn])
(;B[ap]CR[ap]
;W[bn]CR[bn]
(;B[an]CR[an]
;W[dn]CR[dn]C[Ko])
(;B[dn]CR[dn]
;W[cm]CR[cm])
(;B[cp]CR[cp]
;W[an]CR[an])
(;B[cm]CR[cm]
;W[dn]CR[dn]C[Ko])
(;B[ar]CR[ar]
;W[dn]CR[dn]C[Ko])
(;B[dq]CR[dq]
;W[dn]CR[dn]C[Ko]))
(;B[ar]CR[ar]
;W[bn]CR[bn]
(;B[an]CR[an]
;W[dn]CR[dn]C[Ko])
(;B[dn]CR[dn]
;W[cm]CR[cm])
(;B[cm]CR[cm]
;W[dn]CR[dn]C[Ko])
(;B[ap]CR[ap]
;W[dn]CR[dn]C[Ko])
(;B[dq]CR[dq]
;W[dn]CR[dn]C[Ko])
(;B[cp]CR[cp]
;W[dn]CR[dn]C[Ko])))
(;B[bn]CR[bn]
;W[eo]CR[eo]C[Ko])
(;B[an]CR[an]
;W[eo]CR[eo]
;B[do]CR[do]C[Ko. (If black has no good threats he will have to connect at C7, after which white B6 makes the ko severe.)]))
(;B[dn]CR[dn]
;W[bn]CR[bn]
(;B[an]CR[an]
;W[ap]CR[ap])
(;B[dm]CR[dm]
;W[an]CR[an])
(;B[ap]CR[ap]
;W[an]CR[an])
(;B[ar]CR[ar]
;W[an]CR[an])
(;B[do]CR[do]
;W[an]CR[an]))
(;B[do]CR[do]
;W[bn]CR[bn]
(;B[dm]CR[dm]
;W[cp]CR[cp]
(;B[ar]CR[ar]
;W[an]CR[an])
(;B[ap]CR[ap]
;W[an]CR[an])
(;B[an]CR[an]
;W[ap]CR[ap]))
(;B[an]CR[an]
;W[ap]CR[ap])
(;B[cp]CR[cp]
;W[ap]CR[ap])
(;B[dn]CR[dn]
;W[an]CR[an])
(;B[dq]CR[dq]
;W[cp]CR[cp])
(;B[ar]CR[ar]
;W[an]CR[an]))
(;B[bn]CR[bn]
;W[dn]CR[dn]
(;B[dm]CR[dm]
;W[eo]CR[eo]C[Ko])
(;B[ap]CR[ap]
;W[an]CR[an])
(;B[ar]CR[ar]
;W[an]CR[an])
(;B[an]CR[an]
;W[ap]CR[ap])
(;B[cp]CR[cp]
;W[ap]CR[ap]))
(;B[an]CR[an]
;W[bn]CR[bn]
(;B[dm]CR[dm]
;W[eo]CR[eo]
(;B[ap]CR[ap]
;W[dn]CR[dn]C[Ko])
(;B[dn]CR[dn]
;W[do]CR[do])
(;B[do]CR[do]
;W[dn]CR[dn]C[Ko])
(;B[cm]CR[cm]
;W[dn]CR[dn]C[Ko]))
(;B[dn]CR[dn]
;W[ap]CR[ap])
(;B[ap]CR[ap]
;W[cp]CR[cp])
(;B[ar]CR[ar]
;W[ap]CR[ap])))
(;B[ap]CR[ap]
;W[dr]CR[dr]
(;B[ar]CR[ar]
;W[cs]CR[cs]
(;B[cp]CR[cp]
;W[do]CR[do]
(;B[dq]CR[dq]
;W[cr]CR[cr]
(;B[er]CR[er]
;W[bn]CR[bn]
;B[an]CR[an]
;W[cm]CR[cm]
;B[dm]CR[dm]
;W[dn]CR[dn]C[Ko])
(;B[an]CR[an]
;W[cm]CR[cm]
(;B[dm]CR[dm]
;W[bn]CR[bn]
;B[er]CR[er]
;W[dn]CR[dn]C[Ko])
(;B[bn]CR[bn]
;W[dn]CR[dn]
;B[dm]CR[dm]
;W[eo]CR[eo])
(;B[dn]CR[dn]
;W[bn]CR[bn]
;B[dm]CR[dm]
;W[eo]CR[eo]))
(;B[bn]CR[bn]
;W[dn]CR[dn]
(;B[er]CR[er]
;W[cm]CR[cm]
;B[dm]CR[dm]
;W[eo]CR[eo])
(;B[cm]CR[cm]
;W[dm]CR[dm]
;B[er]CR[er]
;W[eo]CR[eo])
(;B[an]CR[an]
;W[cm]CR[cm]
;B[dm]CR[dm]
;W[eo]CR[eo])))
(;B[an]CR[an]
;W[dq]CR[dq]))
(;B[dq]CR[dq]
;W[cp]CR[cp]))
(;B[bs]CR[bs]
;W[cs]CR[cs]
;B[ar]CR[ar]
;W[cr]CR[cr])
(;B[cp]CR[cp]
;W[an]CR[an])
(;B[dq]CR[dq]
;W[cp]CR[cp]
(;B[an]CR[an]
;W[cs]CR[cs])
(;B[ar]CR[ar]
;W[cs]CR[cs]))
(;B[an]CR[an]
;W[cp]CR[cp])
(;B[do]CR[do]
;W[cp]CR[cp]))
(;B[ar]CR[ar]
;W[as]CR[as]
(;B[ap]CR[ap]
;W[dr]CR[dr])
(;B[dq]CR[dq]
;W[cp]CR[cp])
(;B[dr]CR[dr]
;W[cp]CR[cp])
(;B[an]CR[an]
;W[dr]CR[dr]))
(;B[dq]CR[dq]
;W[cp]CR[cp])
(;B[bn]CR[bn]
;W[cp]CR[cp])
(;B[an]CR[an]
;W[cp]CR[cp]
;B[ap]CR[ap]
;W[dr]CR[dr])))
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