I took this hand from the Inaugural Two Worlds Trophy in 1994 as reported by E. Kokish for the now defunct IPBM and gave it to some students. A pair got to six spades and was doubled. They received a heart lead and continuation. There is no mention of how the play went then and there for the 'important' thing was how to get to 6 (only Cohen-Zia got to the slam).
My first thought was that a ruffing finesse was the best line, but then I noticed you can ruff 2 small diamonds in dummy while drawing a trump to check how they behave (2-1), get back to hand while drawing the final trump and then playing the ♦K, which in this case brings out the ♦A and you make your slam. However, how should you play if the third diamond from West is the 10? Is it better to finesse or to try to drop the Ace in East? Does the double lead you in any way? How do probabilities work at this point where diamonds are either 3-3 or 4-2 and neither the Ace or ten were doubleton with East?

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