This problem shows a cool difference between Japanese and Ing rule sets. See also problem #13103.
(;AB[hi]AB[ii]AB[ih]AW[gi]AW[gh]AW[gg]AW[hg]AW[ig]AB[ei]AB[eh]AB[eg]AB[fg]AB[ef]AB[ee]AB[fe]AB[ge]AB[gf]AB[he]AB[ie]AW[id]AW[hd]AW[gd]AW[fd]AW[ed]AW[dd]AW[de]AW[df]AW[dg]AW[dh]AW[di]AB[ce]AB[cd]AB[cc]AB[dc]AB[ec]AB[fc]AB[gc]AW[hc]AW[hb]AW[ha]AW[ib]AB[gb]AB[ga]LB[ba:White]LB[da:Black]C[ING rules - who won? (0.5 komi)FORCE]AB[be]AB[ae]AW[cg]AW[bg]AW[bh]AW[bi]AW[ah]AB[ag]AB[af]AW[bf]AW[cf]SZ[9]AP[goproblems]
(;B[ba]C[Wrong, black wins. See correct answer for explanation.])
(;B[da]
(;W[if]C[Correct. Once again, the game depends on the state of the lower right corner. However, this time, if white decides to fill in liberties, black can sacrifice his four stones in the corner by playing triangle. After this, if white continues to fill in liberties, black can create a seki by playing both of the points marked square. Since black is alive in the lower right, he has enough points to win.FORCERIGHT]TR[hh]MA[hi]MA[ih])
(;W[hf]C[Once again, the game depends on the state of the lower right corner. However, this time, if white decides to fill in liberties, the Ing rules allow black to sacrifice four stones in the corner by playing triangle. Please play at the triangle.CHOICERIGHT]TR[hh];AW[if]AW[fh]AW[fi]B[hh]C[(This is a trick to remove the 4 stones. The white stones should appear to not have been away. Just blink at the right moment:)];AW[gg]AW[gh]AW[gi]AW[hg]AW[if]AW[hf]W[ig]C[The 4 Black stones are removed as soon as Black plays the suicide (which Ing rules allow but Japanese rules forbid). Next, White takes another liberty at the squared position. Ignore the circle mark: that is just a hack needed to make this possible]TR[ih]MA[if];B[ih];W[fi]TR[hi];B[hi]C[If white continues to fill in liberties, black can create a seki by playing in the corner. Almost anything will do. Since black is alive in the lower right, he has enough points to win.RIGHT])))
