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Oct 17, 2019 at 7:45 history edited YCor
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Apr 16, 2019 at 2:33 vote accept David G. Stork
Apr 15, 2019 at 23:10 answer added Tony Huynh timeline score: 7
Apr 15, 2019 at 23:03 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 22:58 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 22:51 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 21:52 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 21:39 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 18:01 comment added David G. Stork @MichaelJoyce: Interesting point. I know it wasn't your point, but your alternate recoding doesn't change the answer to my questions, does it?
Apr 15, 2019 at 16:59 comment added Michael Joyce A comment about the trick itself: You can vary where the card identifying the suit appears as follows. After the assistant gives the mystery card to the mark, they add the ranks of the remaining 4 cards modulo 4 and use that number to determine the position of the suit card, which the magician can recover with the same computation. The order of the other three cards is determined by ignoring the suit card. This small addition to the trick makes it much harder for the mark to crack.
Apr 15, 2019 at 8:11 comment added Ilya Bogdanov Clearly, the 5-tuples with exactly one working sequences are exactly those with exactly one pair of cards of the same suit, and they can be counted easily.
Apr 15, 2019 at 7:13 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 6:07 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 5:37 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 4:53 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 4:39 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 4:37 comment added Alex Kruckman I didn't claim that every sequence of four cards was possible (this would be $52*51*50*49$), but rather that the method defines an injective function from hands of $5$ cards to sequences of $4$ cards, the image of which is the set you're trying to count. But based on your edit, I see what I was missing - based on your specification of the method, for some hands the assistant has multiple choices.
Apr 15, 2019 at 4:34 comment added David G. Stork Nope. Can $\spadesuit 3\ \spadesuit 4\ \spadesuit 5\ \spadesuit 6$ ever be an exposed sequence?
Apr 15, 2019 at 4:33 comment added Alex Kruckman Maybe I don't understand the question, but isn't the answer obviously ${52 \choose 5}$?
Apr 15, 2019 at 4:32 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 4:20 history edited KConrad CC BY-SA 4.0
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Apr 15, 2019 at 4:14 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 4:08 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 4:01 history edited David G. Stork CC BY-SA 4.0
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Apr 15, 2019 at 3:48 history asked David G. Stork CC BY-SA 4.0