Problem 13083 goproblems.com


Author	ndkrempel	Created	2009-09-15
Difficulty	7 dan (history)	Source	Li Chang Ho Jingjiang Weiqi Sihuo, volume 6, number 101
AVG solve time	101 sec	Stars	4 (2 votes)
User attempts	30 / 374	Collections	Corner based
Genre	life and death ⓢ	Your attempts	N/A
Similar problems
Created	2009-09-15
Source	Li Chang Ho Jingjiang Weiqi Sihuo, volume 6, number 101
Stars	4 (2 votes)
Collections	Corner based
Your attempts	N/A

(;AW[dp]AW[ep]AW[fq]AW[fr]AW[fs]AW[co]AW[bo]AW[bm]AB[bp]AB[cp]AB[cr]AB[er]AB[es]AP[goproblems] (;W[br] (;B[ar]C[CHOICE] (;W[aq];B[bq];W[as];B[ap] (;W[dq]C[];B[ar]C[Good, a 2-step ko. This is the best result for both, try again to see some other variations.RIGHT]) (;W[ao];B[ar]C[Nearly, but this way gives black more local ko threats.])) (;W[bs];B[bq];W[dq];B[ap]) (;W[bq];B[cq];W[bs];B[dr] (;W[cs];B[aq]) (;W[aq];B[ap]) (;W[ap];B[aq] (;W[as];B[aq] (;W[ar];B[cs] (;W[ao];B[aq]) (;W[aq];B[ao])) (;W[ao];B[cs];W[ar];B[aq])) (;W[ao];B[cs];W[as];B[aq];W[ar];B[aq]) (;W[cs];B[ao])))) (;B[bq]C[CHOICE] (;W[ar] (;B[aq];W[dq] (;B[bs];W[dr]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;B[dr];W[cq]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;B[cq];W[dr]C[Good. Black has a stronger defense - try again to see it.RIGHT])) (;B[cq]C[CHOICE] (;W[cs] (;B[bs] (;W[dr];B[dq];W[ap];B[ds];W[aq]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;W[ap];B[aq];W[dr];B[as] (;W[dq]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;W[eq]C[Good. Black has a stronger defense - try again to see it.RIGHT])) (;W[dq];B[dr] (;W[as];B[ap]) (;W[ap];B[aq])) (;W[as];B[aq] (;W[bs];B[dq]) (;W[dr];B[bs] (;W[ar];B[dq]) (;W[dq];B[ar]) (;W[eq];B[ar])) (;W[dq];B[bs] (;W[ar];B[dr]) (;W[dr];B[ar])))) (;B[dr] (;W[bs];B[aq] (;W[as]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;W[eq];B[ds];W[dq];B[as];W[bs];B[br];W[ar])) (;W[ap];B[aq] (;W[bs];B[ds] (;W[eq];B[as];W[bs];B[br];W[ar]) (;W[ao];B[as];W[bs];B[br];W[ar];B[cs]) (;W[dq];B[as];W[bs];B[br];W[ar])) (;W[ao];B[bs]) (;W[eq];B[bs]) (;W[dq];B[bs])))) (;W[dq];B[dr] (;W[cs];B[bs] (;W[as];B[ap]) (;W[ap];B[aq])) (;W[ap];B[aq] (;W[cs];B[bs]) (;W[bs];B[cs])) (;W[bs];B[cs];W[ap];B[aq])) (;W[ap];B[aq] (;W[dq];B[dr] (;W[cs];B[bs]) (;W[bs];B[cs])) (;W[cs];B[dr] (;W[bs];B[ds] (;W[eq];B[as];W[bs];B[br];W[ar]) (;W[ao];B[as];W[bs];B[br];W[ar];B[cs]) (;W[dq];B[as];W[bs];B[br];W[ar])) (;W[ao];B[bs]) (;W[eq];B[bs]) (;W[dq];B[bs])) (;W[bs] (;B[dq] (;W[eq];B[ds]) (;W[ds];B[cs];W[eq];B[as] (;W[dr];B[br]) (;W[br];B[dr]))) (;B[cs] (;W[dq];B[dr]) (;W[dr];B[as] (;W[dq];B[br]) (;W[br];B[dq])))) (;W[dr];B[dq] (;W[eq];B[ds]) (;W[cs];B[ds];W[eq];B[bs])) (;W[ds];B[dr])) (;W[dr];B[dq]) (;W[bs] (;B[aq] (;W[cs];B[dr];W[as]C[FORCERIGHT]) (;W[dq];B[dr];W[cs];B[ds];W[eq];B[as];W[bs];B[br];W[ar])) (;B[cs];W[dr];B[dq];W[eq];B[ds];W[ap]C[RIGHT]))) (;B[dq];W[ap]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;B[bs] (;W[ap]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;W[dq] (;B[dr] (;W[ap]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;W[cq]C[Good. Black has a stronger defense - try again to see it.RIGHT])) (;B[aq];W[dr]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;B[cq];W[dr]C[Good. Black has a stronger defense - try again to see it.RIGHT])))) (;W[dq];B[dr];W[ar];B[cq] (;W[cs];B[bs] (;W[ap];B[aq]) (;W[as];B[ap])) (;W[ap];B[aq] (;W[bs];B[cs]) (;W[cs];B[bs]))) (;W[bs];B[cs] (;W[dq];B[dr]) (;W[ar];B[aq]) (;W[ap];B[ar]) (;W[aq];B[ap]) (;W[dr];B[dq])) (;W[cs];B[dr];W[ar];B[aq];W[bs];B[ds];W[dq];B[as];W[bs];B[br];W[ar];B[cs])) (;B[cq]C[CHOICE] (;W[cs];B[bs];W[as];B[ds] (;W[dq];B[bs]) (;W[eq];B[bs]) (;W[bs];B[bq] (;W[ap];B[dq]) (;W[dq];B[ar] (;W[bs];B[ap]) (;W[ap];B[bs])) (;W[ar];B[dq]) (;W[eq];B[ar] (;W[bs];B[ap]) (;W[ap];B[dq]))) (;W[ap];B[bs])) (;W[bs];B[cs];W[dr];B[dq];W[eq];B[ds];W[aq];B[ap];W[ao];B[ar];W[as]) (;W[dr];B[dq];W[eq];B[ds];W[bs];B[cs];W[aq];B[ap];W[ao];B[ar];W[as]) (;W[dq];B[dr];W[cs];B[ap] (;W[ar];B[bs]) (;W[bs];B[ar] (;W[bq];B[aq]) (;W[as];B[bq];W[aq];B[ds])) (;W[aq];B[as];W[bs];B[bq] (;W[ao];B[ar];W[aq];B[ar]) (;W[ar];B[ds])) (;W[as];B[aq])) (;W[ap]C[] (;B[aq] (;W[dq];B[dr];W[cs];B[ao] (;W[an];B[ap] (;W[bs];B[ar]) (;W[ar];B[bs])) (;W[bs];B[ar];W[an];B[ap]) (;W[ar];B[bs])) (;W[cs] (;B[bs];W[as];B[ds];W[bs]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;B[ds];W[bs]C[Good. Black has a stronger defense - try again to see it.RIGHT]))) (;B[ar];W[bs] (;B[bq];W[dq];B[dr];W[cs]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;B[cs]C[CHOICE] (;W[dr];B[dq];W[eq];B[ds] (;W[bq]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;W[aq]C[Good. Black has a stronger defense - try again to see it.RIGHT])) (;W[aq];B[bq];W[dr];B[ao] (;W[dq];B[ap]) (;W[ap];B[dq])) (;W[bq];B[aq] (;W[as];B[aq] (;W[ar];B[aq]) (;W[dr];B[ar])) (;W[dr];B[as] (;W[dq];B[br]) (;W[br];B[dq])))) (;B[aq];W[cs] (;B[dr];W[ao]C[Good. Black has a stronger defense - try again to see it.RIGHT]) (;B[dq];W[eq];B[dr];W[ao]C[Good. Black has a stronger defense - try again to see it.RIGHT]))))) (;B[ap]) (;B[aq]) (;B[bs])) (;W[ar];B[br] (;W[dq];B[as] (;W[cq];B[bq] (;W[bs];B[cs] (;W[dr];B[aq]) (;W[as];B[dr]) (;W[ap];B[aq])) (;W[cs];B[dr];W[bs];B[ap]) (;W[dr];B[cs];W[bs];B[aq])) (;W[bs];B[aq] (;W[cq];B[bq] (;W[cs];B[dr] (;W[eq];B[as]C[This ko is not as good as the correct solution.]) (;W[as];B[ds];W[bs];B[as];W[ar];B[cs])) (;W[dr];B[cs]) (;W[as];B[dr];W[cs];B[ds];W[bs];B[as];W[ar];B[cs])) (;W[cs];B[dr];W[cq];B[bq] (;W[eq];B[as]C[This ko is not as good as the correct solution.]) (;W[as];B[ds];W[bs];B[as];W[ar];B[cs])) (;W[dr];B[cs];W[cq];B[bq])) (;W[aq];B[ap];W[bs];B[dr];W[cq];B[bq];W[cs];B[ds]) (;W[cs];B[dr];W[bs];B[ap]) (;W[dr];B[cs] (;W[bs];B[aq];W[cq];B[bq]) (;W[cq];B[bq];W[bs];B[aq]) (;W[aq];B[ap];W[bs];B[bq]))) (;W[ap];B[bq] (;W[dq];B[as] (;W[bs];B[aq];W[cs];B[dr] (;W[eq];B[as]C[This ko is not as good as the correct solution.]) (;W[as];B[ds];W[bs];B[as];W[ar];B[cs]) (;W[ao];B[ds]) (;W[cq];B[as]C[This ko is not as good as the correct solution.])) (;W[cs];B[dr];W[bs];B[aq] (;W[eq];B[as]C[This ko is not as good as the correct solution.]) (;W[ao];B[ds]) (;W[as];B[ds];W[bs];B[as];W[ar];B[cs]) (;W[cq];B[as]C[This ko is not as good as the correct solution.]))) (;W[aq];B[dq]))) (;W[dq];B[ar] (;W[bs];B[dr];W[cq];B[cs] (;W[bq];B[br]) (;W[br];B[bq];W[ap];B[as])) (;W[dr];B[bs]) (;W[ap];B[bs] (;W[bq];B[cq] (;W[dr];B[aq]) (;W[aq];B[dr])) (;W[dr];B[cq])) (;W[bq];B[cq];W[ap];B[br])) (;W[ap];B[ar] (;W[bs];B[dq] (;W[bq];B[cq];W[br];B[aq] (;W[eq];B[cs];W[dr];B[as] (;W[ds];B[br]) (;W[br];B[ds])) (;W[as];B[aq] (;W[ar];B[cs] (;W[aq];B[ao]) (;W[ao];B[aq])) (;W[ao];B[cs];W[ar];B[aq])) (;W[ao];B[cs];W[as];B[aq];W[ar];B[aq])) (;W[eq];B[br] (;W[cs];B[as];W[ds];B[dr]) (;W[bq];B[cq];W[cs];B[as])) (;W[cs];B[br] (;W[eq];B[as];W[ds];B[dr]) (;W[bq];B[cq];W[eq];B[as]))) (;W[dq];B[bs] (;W[dr];B[cq]) (;W[bq];B[cq] (;W[aq];B[dr]) (;W[dr];B[aq])))))