Problem	12966
Created	2009-08-12
Source	"Learn to Play Go, Vol V"; Janice Kim; page 208.
Rating

Difficulty	7 dan
Average Solve Time	69 secs
User Attempts	74 / 285
Solve Ratio Rating	3 kyu
	rating history

Given the weakness of the Black group in the corner, what is best for Black here?

(;AB[aa]AB[ba]AB[bc]AB[ac]AB[cb]AB[db]AB[bd]AB[cd]AB[be]AB[ed]AB[fd]AB[fc]AB[gb]AB[ge]AB[gf]AB[if]AB[ie]AB[id]AB[kd]AW[cc]AW[dc]AW[ec]AW[eb]AW[ga]AW[dd]AW[ce]AW[de]AW[ee]AW[fe]AW[bf]AW[cg]AW[ci]AW[fg]AW[gg]C[Black to play, and make the best endgame move. Be careful to save the Black group in the corner.]AP[goproblems] (;B[ha] (;W[ea] (;B[da];W[fb] (;B[hc]C[Correct.RIGHT]) (;B[hb]C[Correct.RIGHT]) (;B[fa];W[gc] (;B[gd] (;W[hc]C[Black can do better as this can lead to a ko.CHOICE])) (;B[hc];W[gd]C[Black can do better than this.CHOICE])) (;B[gc];W[hb]C[Black can do better than this ko.CHOICE])) (;B[fa];W[da]LB[bb:A]LB[ae:B]C[The Black group in the corner is dead. A & B are miai.CHOICE]) (;B[ae];W[fb] (;B[hb]C[Correct.RIGHT]) (;B[hc]C[Correct.RIGHT]) (;B[fa];W[gc] (;B[gd];W[hc]C[Black can do better as this can lead to a ko.CHOICE]) (;B[hc];W[gd]C[Black can do better than this.CHOICE])) (;B[gc];W[hb]C[Black can do better than this ko.CHOICE])) (;B[gc];W[da]C[The Black group in the corner is dead.CHOICE])) (;W[hb] (;B[da];W[fa] (;B[ib];W[hc]C[White wins.CHOICE]) (;B[hc];W[ib]C[White wins.CHOICE])) (;B[ae];W[fa] (;B[hc];W[ib]C[White wins.CHOICE]) (;B[ib];W[hc]C[White wins.CHOICE])) (;B[fa];W[fb] (;B[ea];W[gc]C[Black can do better than this ko.CHOICE]) (;B[gc];W[ea]C[Black must defend the corner, so White gets to play the ko at A first.CHOICE]LB[ga:A]) (;B[ga];W[gc]C[Black can do better than this.CHOICE]) (;B[hc];W[ea] (;B[da];W[ga] (;B[ib]C[Correct.RIGHT]) (;B[gc];W[ia]C[Black can do better than this.CHOICE]) (;B[ic];W[gc]C[Black can do better than this.CHOICE])) (;B[ae];W[ga] (;B[ib]C[Correct.RIGHT]) (;B[gc];W[ia]C[Black can do better than this.CHOICE]) (;B[ic];W[gc]C[Black can do better than this.CHOICE])) (;B[ga];W[da]C[The Black group in the corner is dead.CHOICE]) (;B[ib];W[da]C[The Black group in the corner is dead.CHOICE])) (;B[ib];W[ea]C[Black must defend the corner, so White gets to play A.CHOICE]LB[gc:A]) (;B[da];W[gc]C[Black can do better than this ko.CHOICE]) (;B[ae];W[gc]C[Black can do better than this ko.CHOICE])) (;B[fb];W[ea]C[Black can do better as she must defend the corner, so White gets to play A.CHOICE]LB[fa:A]) (;B[hc];W[ea]C[Black can do better as she must defend the corner, and White gets to play A.CHOICE]LB[ia:A]) (;B[ib];W[ea]LB[hc:A]C[Black can do better as she must defend the corner, and White gets to play A.]))) (;B[fa];W[fb] (;B[gc];W[ha]C[Black can do better than this.CHOICE]) (;B[ea];W[gc]C[Black can do better than this.CHOICE]) (;B[hb];W[ea]LB[ha:A]C[Black can do better as she must defend the corner, and White gets to play A.CHOICE]) (;B[ha];W[ea]LB[gc:A]C[Black can do better as she must defend the corner, and White gets to play at A, which can lead to a ko.CHOICE])) (;B[fb];W[ea] (;B[fa];W[da]LB[bb:A]LB[ae:B]C[The Black group in the corner is dead. A & B are miai.CHOICE]) (;B[da];W[fa]C[Black can do better than this.CHOICE]) (;B[ae];W[fa]C[Black can do better than this.CHOICE]) (;B[ha];W[da]C[The Black group in the corner is dead.CHOICE])) (;B[ea]C[White wins];W[fa] (;B[da];W[fb]C[Black can do better then this.CHOICE]) (;B[fb];W[da]C[Black must save the group in the corner, and White will get to play A.CHOICE]LB[hb:A]) (;B[ae];W[hb]C[White wins.CHOICE]) (;B[ha];W[da]LB[hb:A]C[Black must defend the group in the corner. White then gets to play A.CHOICE]) (;B[hb];W[ha]C[Black can do better than this.CHOICE])) (;B[da];W[fb]C[Black can do better then this.CHOICE]) (;B[hb];W[ea] (;B[ae];W[ha]C[Black can do better than this.CHOICE]) (;B[da];W[ha]C[Black can do better than this.CHOICE]) (;B[ha];W[da]LB[bb:A]LB[ae:B]C[The Black group in the corner is dead. A & B are miai.CHOICE]) (;B[fb];W[da]LB[bb:A]LB[ae:B]C[The Black group in the corner is dead. A & B are miai.CHOICE])) (;B[ae];W[ha]C[Black can do better than this.CHOICE]) (;B[hc];W[ea]LB[ia:A]C[Black can do better as she must defend the corner, and White gets to play at A.CHOICE]) (;B[ca];W[fb]LB[ae:A]LB[gc:B]C[Black must defend at A, so White can play B.CHOICE]) (;B[bb];W[ha]C[Black can do better than this.CHOICE]))