RetrogradeAnalysisProblem8 / Attempts

NONE!!! Or are you assuming perfect play?

B5 at W2  

Coconuts: 22 with 4x symmetry. We know because only one white stone sits on the board after five moves that W2 was captured, limiting W2 to the corner and the side. Because we know which move B5 is, it can't be a move to capture, but a move where the white stone was. So that puts us in the corner. Now, W4 can go wherever we want it to, so there are 22 different board points (25 points - 3 taken up) for it. There are four corners and we can move the position into any of them, so we end up with: 22 x 4 = 88. I think that's right!

ferdi: Not bad, but there are some more :-)


unkx80: In this position, given that one White stone must be captured at a, black+circle is the only legal move for B5. After accounting for symmetry, there are 8 such positions.

RetrogradeAnalysisProblem8 / Attempts last edited by ferdi on December 18, 2004 - 10:03
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