Problem 13369 goproblems.com


Author	BartTM	Created	2010-01-05
Difficulty	5 dan (history)	Source	Problem 13354
AVG solve time	71 sec	Stars	3.5 (10 votes)
User attempts	222 / 753	Collections	N/A
Genre	life and death ⓒ	Your attempts	N/A
Similar problems
Created	2010-01-05
Source	Problem 13354
Stars	3.5 (10 votes)
Collections	N/A
Your attempts	N/A

(;AW[ra]AW[qb]AW[pb]AW[pc]AW[od]AW[oe]AW[pe]AW[qe]AB[pd]AB[qd]AB[qc]AB[rb]AB[oc]AB[nc]AB[nd]TR[ra]C[If White plays S19 in problem 13354 things get complicated. Find the best possible continuation.]AP[goproblems] (;B[sb] (;W[rd] (;B[rc];W[se] (;B[qa];W[pa] (;B[ob];W[sc] (;B[sd]C[Ko, Black takes first.RIGHT]) (;B[oa];W[sa]) (;B[re];W[sa])) (;B[oa];W[ob] (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[na] (;B[sd];W[sc]C[Ko, White takes first]) (;B[ma];W[sc] (;B[oa];W[sa]) (;B[sd]C[Ko, Black takes first.RIGHT])) (;B[sa];W[sc]) (;B[sc];W[sd]) (;B[re];W[rf];B[ma];W[sc];B[sd]C[Yeah, right.RIGHT])) (;B[re];W[rf];B[nb];W[na];B[ma];W[sc];B[sd]C[Yeah, right.RIGHT]) (;B[na];W[nb])) (;B[sc];W[sd]) (;B[sd];W[sc]C[Ko, White takes first.]) (;B[re];W[rf] (;B[ob];W[sc];B[sd]C[RIGHT]) (;B[oa];W[sc];B[sd]C[RIGHT]) (;B[sd];W[sc]C[Ko, White takes first.])) (;B[sa];W[sc])) (;B[pa];W[ob] (;B[nb];W[oa]) (;B[qa];W[oa] (;B[qa];W[sd]) (;B[sd];W[re] (;B[qa];W[sc]C[Ko, White takes first.]) (;B[nb];W[qa]) (;B[na];W[qa])) (;B[nb];W[qa]) (;B[na];W[qa])) (;B[oa];W[nb]) (;B[sd];W[re] (;B[nb];W[oa]) (;B[qa];W[oa] (;B[qa];W[sc]C[Ko, White takes first.]) (;B[nb];W[qa]) (;B[na];W[qa])) (;B[oa];W[nb]))) (;B[sd];W[sc]C[Ko, White takes first.]) (;B[re];W[rf] (;B[ob];W[sc] (;B[sd]C[Ko, Black takes first.RIGHT]) (;B[pa];W[sa]) (;B[qa];W[sa])) (;B[sd];W[sc]C[Ko, White takes first.]) (;B[qa];W[pa] (;B[ob];W[sc];B[sd]C[RIGHT]) (;B[oa];W[sc];B[sd]C[RIGHT]) (;B[sd];W[sc]C[Ko, White takes first.])) (;B[pa];W[ob] (;B[qa];W[oa] (;B[qa];W[sd]) (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[qa]) (;B[na];W[qa]) (;B[sa];W[sc])) (;B[sa];W[sc]) (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[oa]) (;B[oa];W[nb]))) (;B[ob];W[sc];B[sd]C[Ko, Black takes first.RIGHT])) (;B[ob];W[rc]) (;B[re];W[rc])) (;W[qa];B[rc] (;W[rd];B[re]C[RIGHT]) (;W[re];B[ob];W[rd];B[oa]C[RIGHT]) (;W[ob];B[nb] (;W[oa];B[na]C[RIGHT]) (;W[re];B[oa];W[rd];B[na]C[RIGHT]))) (;W[rc];B[rd];W[re];B[sc];W[se];B[sd]C[RIGHT]) (;W[sc];B[sd];W[rd];B[rc];W[re];B[ob]C[RIGHT]) (;W[sd];B[rc];W[rd];B[re];W[rf];B[ob]C[RIGHT]) (;W[re];B[rc];W[rd];B[ob]C[RIGHT]) (;W[se]C[You descended to the first line and so did White. Strange, innocent? Guess you will find out pretty soon :)CHOICE] (;B[rc];W[rd] (;B[qa];W[pa] (;B[ob];W[sc] (;B[sd]C[Ko, Black takes first.RIGHT]) (;B[oa];W[sa]) (;B[re];W[sa])) (;B[oa];W[ob] (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[na] (;B[sd];W[sc]C[Ko, White takes first]) (;B[ma];W[sc] (;B[oa];W[sa]) (;B[sd]C[Ko, Black takes first.RIGHT])) (;B[sa];W[sc]) (;B[sc];W[sd]) (;B[re];W[rf];B[ma];W[sc];B[sd]C[Yeah, right.RIGHT])) (;B[re];W[rf];B[nb];W[na]) (;B[na];W[nb])) (;B[sc];W[sd]) (;B[sd];W[sc]C[Ko, White takes first.]) (;B[re];W[rf] (;B[ob];W[sc];B[sd]C[RIGHT]) (;B[oa];W[sc];B[sd]C[RIGHT]) (;B[sd];W[sc]C[Ko, White takes first.])) (;B[sa];W[sc])) (;B[pa];W[ob] (;B[nb];W[oa]) (;B[qa];W[oa] (;B[qa];W[sd]) (;B[sd];W[re] (;B[qa];W[sc]C[Ko, White takes first.]) (;B[nb];W[qa]) (;B[na];W[qa])) (;B[nb];W[qa]) (;B[na];W[qa])) (;B[oa];W[nb]) (;B[sd];W[re] (;B[nb];W[oa]) (;B[qa];W[oa]) (;B[oa];W[nb]))) (;B[sd];W[sc]C[Ko, White takes first.]) (;B[re];W[rf] (;B[ob];W[sc] (;B[sd]C[Ko, Black takes first.RIGHT]) (;B[pa];W[sa]) (;B[qa];W[sa])) (;B[sd];W[sc]C[Ko, White takes first.]) (;B[qa];W[pa]) (;B[pa];W[ob] (;B[qa];W[oa] (;B[qa];W[sd]) (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[qa]) (;B[na];W[qa]) (;B[sa];W[sc])) (;B[sa];W[sc]) (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[oa]) (;B[oa];W[nb]))) (;B[ob];W[sc];B[sd]C[Ko, Black takes first.RIGHT])) (;B[ob];W[rc] (;B[pa];W[rd]) (;B[qa];W[rd]) (;B[rd];W[re] (;B[sc];W[sd]) (;B[pa];W[sd]) (;B[sd];W[sc])) (;B[re];W[rd]) (;B[sc];W[rd]) (;B[sd];W[rd])) (;B[rd];W[sd] (;B[ob];W[re]) (;B[re];W[rf] (;B[rc];W[sf]) (;B[ob];W[rc]) (;B[sc];W[rc]) (;B[sf];W[rc])) (;B[rc];W[re]) (;B[sc];W[re])) (;B[sd];W[rd] (;B[rc];W[sc]C[Ko, White takes first.]) (;B[ob];W[rc]) (;B[sc];W[rc])) (;B[re];W[rf] (;B[sd];W[rc] (;B[rd];W[sc]) (;B[sf];W[rd]) (;B[sc];W[rd]) (;B[ob];W[rd])) (;B[rc];W[rd] (;B[ob];W[sc] (;B[sd]C[Ko, Black takes first.RIGHT]) (;B[pa];W[sa]) (;B[qa];W[sa])) (;B[sd];W[sc]C[Ko, White takes first.]) (;B[qa];W[pa]) (;B[pa];W[ob] (;B[qa];W[oa] (;B[qa];W[sd]) (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[qa]) (;B[na];W[qa]) (;B[sa];W[sc])) (;B[sa];W[sc]) (;B[sd];W[sc]C[Ko, White takes first]) (;B[nb];W[oa]) (;B[oa];W[nb]))) (;B[rd];W[sd] (;B[rc];W[sf]) (;B[ob];W[rc]) (;B[sc];W[rc]) (;B[sf];W[rc])) (;B[sc];W[rd]) (;B[ob];W[rc]) (;B[sf];W[rc]) (;B[qa];W[rc])) (;B[sc];W[rd]) (;B[qa];W[rc];B[rd];W[sd];B[sc];W[re]))) (;B[rc];W[sb] (;B[sc];W[sd] (;B[sa];W[qa] (;B[se];W[sb]C[Ko, White takes first]) (;B[ob];W[sb]C[Ko, White takes first]) (;B[rd];W[re] (;B[se];W[sb]C[Ko, White takes first]) (;B[ob];W[sb])) (;B[re];W[rf] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[rd];W[sf] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[se];W[sb]C[Ko, White takes first.]) (;B[sb];W[se])) (;B[sb];W[rd]) (;B[se];W[sf] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[rd];W[sb]C[Ko, White takes first.])))) (;B[rd];W[re]) (;B[re];W[rd]) (;B[ob];W[rd]) (;B[se];W[rd]) (;B[qa];W[rd])) (;B[re];W[sc];B[rd];W[rf]) (;B[ob];W[rd]) (;B[sd];W[re] (;B[sc];W[rd];B[sa];W[qa];B[ob];W[sb]C[Ko, White takes first.]) (;B[ob];W[rd]) (;B[rd];W[se])) (;B[rd];W[re]) (;B[se];W[rd]) (;B[qa];W[pa] (;B[sc];W[sd];B[sa];W[qa] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[rd];W[re] (;B[se];W[sb]C[Ko, White takes first.]) (;B[ob];W[sb]) (;B[oa];W[sb])) (;B[oa];W[sb]C[Ko, White takes first.]) (;B[re];W[rf] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[oa];W[sb]C[Ko, White takes first.]) (;B[rd];W[sf] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[se];W[sb]C[Ko, White takes first.]) (;B[oa];W[sb]C[Ko, White takes first.])) (;B[se];W[sf] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[oa];W[sb]C[Ko, White takes first.]) (;B[rd];W[sb]C[Ko, White takes first.]))) (;B[se];W[re] (;B[rd];W[sb]C[Ko, White takes first.]) (;B[ob];W[sb]C[Ko, White takes first.]) (;B[oa];W[sb]C[Ko, White takes first.]))) (;B[ob];W[rd]) (;B[oa];W[rd]) (;B[sd];W[re] (;B[sc];W[rd];B[sa];W[qa] (;B[ob];W[sb]C[Ko, White takes first.]) (;B[oa];W[sb]C[Ko, White takes first.])) (;B[ob];W[rd]) (;B[oa];W[rd])) (;B[rd];W[re]) (;B[re];W[sc];B[rd];W[rf]) (;B[se];W[rd]))) (;B[sc];W[rd]) (;B[rd] (;W[sb] (;B[sc];W[rc]C[Ko, White takes first.]) (;B[rc];W[re]) (;B[sd];W[rc]) (;B[re];W[rc]C[Whiote could also play S14 for a favourable ko.]) (;B[se];W[rc]) (;B[ob];W[rc])) (;W[re]C[In general S15 will be a better defense for White than T18, but it may depend on the situation on the rest of the board.] (;B[sc];W[se] (;B[sd];W[sb] (;B[sa];W[qa];B[ob];W[sb]C[Ko, White takes first.]) (;B[ob];W[rc]) (;B[qa];W[rc])) (;B[ob];W[sd]) (;B[qa];W[sd]) (;B[sb];W[sd])) (;B[sd];W[sb] (;B[sc];W[rc]C[Ko, White takes first.]) (;B[se];W[rg]) (;B[ob];W[rc]) (;B[qa];W[rc])) (;B[sb];W[sd]) (;B[se];W[sf] (;B[sc];W[sd]MA[sb]C[Dead in double ko. If Black retakes at T15 White will play T18.]) (;B[sd];W[sc]) (;B[rc];W[sd]) (;B[sb];W[sd] (;B[rc];W[se]) (;B[ob];W[rc])) (;B[ob];W[sd]) (;B[qa];W[sd] (;B[rc];W[pa] (;B[sb];W[se]) (;B[ob];W[sb])) (;B[sa];W[rc]) (;B[sc];W[rc]) (;B[ob];W[rc])) (;B[rf];W[sd])) (;B[rc];W[sb]) (;B[sa];W[sd] (;B[qa];W[rc]) (;B[sc];W[rc]) (;B[rc];W[sb]) (;B[ob];W[rc])) (;B[ob];W[sd]) (;B[qa];W[sd] (;B[rc];W[pa] (;B[sb];W[se]) (;B[ob];W[sb])) (;B[sa];W[rc]) (;B[ob];W[rc]) (;B[sc];W[rc])))) (;B[re];W[sb] (;B[rf];W[rd]) (;B[rd];W[rc]C[Whiote could also play S14 for a favourable ko.]) (;B[rc];W[sc];B[rd];W[rf]) (;B[sc];W[rd]) (;B[sd];W[rc]) (;B[se];W[rd])) (;B[sd] (;W[rc];B[rd];W[sb]C[White lives (Thanks to Bass)]) (;W[sb];B[rc];W[re] (;B[sc];W[rd];B[sa];W[qa];B[ob];W[sb]C[Ko, White takes first.]) (;B[ob];W[rd]) (;B[rd];W[se])) (;W[rd];B[rc];W[re];B[sb];W[se];B[ob];W[sc])) (;B[se];W[rd]) (;B[ob];W[rd]) (;B[qa];W[rc] (;B[rd];W[sb]) (;B[sa];W[rd]) (;B[ob];W[sb])) (;B[pa];W[rd]) (;B[sa];W[rc]))