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Old 08-26-2016, 10:22 PM
Indistinguishable Indistinguishable is offline
Join Date: Apr 2007
Posts: 10,512
It's worth noting that there's two basic modes for these tricks: creating an injective [and indeed easily invertible] function, as in trick 1 in this thread (where the trickster can deduce the input from the trickee telling them the output), and creating a constant function, as in trick 2 in this thread (where the trickster can deduce the output even without knowing the trickee's input).

The latter form, though it sounds so unimpressive written out as just "this function turns out to be constant", connects to fond memories for me, as it was what they used to use at the end of some episodes of Square One TV, my first exposure to these tricks as a child (obviously, on TV, the interactivity required for the former couldn't be employed).

Last edited by Indistinguishable; 08-26-2016 at 10:27 PM.