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Thu 2012-11-22 14:38 |
By the Curry-Howard Isomorphism, constructive proofs correspond to functions (from correlates of assumptions to correlates of conclusions) - and an alternate proof often corresponds to an alternate function.
The Schroeder-Bernstein construction works for sets in general. But sets of concrete things such as emails are always at most countably infinite. So there's an alternative proof. You can compose the two bijections - quoted emails to integers and then from integers to unquoted emails. This is nonconstructive because I haven't pinned down what those (Godel numbering) bijections actually are, but it might look like a complete mess.
The 103...496th possible email not containing a specific byte sequence ("\nFrom" or whatever) might not have much superficial visual similarity to the 103...496th possible email when that byte sequence is allowed. |
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