(;
AB[dq][dr][ds][ep][fp][gp][hp][ip][jp][kp][lp][mq][mr][ns][or]
AW[eq][fq][gq][hq][hs][iq][jq][kq][lq]
C[Black plays.

Source:  a Korean dan level problem set.

Also see goproblems.com #222, which copies the problem.];
B[fs]
C[The only move!];
W[lr];B[gs]
C[Again, the only move!

How can such a simple game as go produce such unique cool moves?!];
W[gr]
(;
B[js]
C[The Korean problem set gives this move as a correct play sequence.

But depending on the rest of the board, this move may not be best.];
W[ks];B[is];W[ir]
C[Yes, Black does have a direct ko.  However, Black has no local ko threats with this sequence.]
)
    (;
    B[is]
    C[The Korean problem set also gives this move as correct.
    
But isn't this move always THE best choice?  Given no knowledge about the rest of the board, the following sequence is better than the previous variation.];
    W[ir]
    LB[js:A]
    C[Black still has the huge ko, but now Black also has an important extra local ko threat at A.];
    B[js]
    C[For example, ...];
    W[ks];B[hr]
    C[... and White has to find a 2nd outside ko threat.  So far, Black hasn't had to find even one.]
    )
    (;
    B[ls]
    C[This variation also appears in the Korean "solution", and similarly seems to waste a ko threat.];
    W[ks];B[is];W[ir]
    C[Black has no local ko threats.]
    )
)

