Non-computability.

According to Roger Penrose, humans can perform non-computable feats, such as dealing with Gödel questions. He uses this as a foundation to claim that the human mind cannot be expressed in terms of classical processes, and as such must be party to the only other (known) game in town: Quantum Mechanics.

Now, I haven't had the patience to sit through all of his arguments yet, though I slowly make progress. My understanding is that a large part of his stance is that an algorithm cannot usefully deal with a Gödel question, or equivalently, with the halting problem, while a human can.

My objection to this is that such problems always demand a certain quality of response when asked of UTMs: failing to respond forever is not acceptable as correct, nor is providing any response other than one that yields a truth when taken in combination with the question. This much is fine, however, when it is time for the human to answer, he is permitted the liberty of rejecting the question on the grounds that it is inherently unanswerable.

Obviously I am interested in artificial intelligence, and also find his assertion to be simply a self-serving one with a contrived philosophical backdrop for foundation. If anyone knows of, or can think of, a more sophisticated argument than the one above (or expose my flaws in my assessment of it) I would like to hear it.

Apologies for bringing up a largely philosophical question, my only excuse is that I cannot trust any other board with the question.

1. Use perl -ne 'print if /mailto:(?!sage)/' and do that all in one step. Why fork two processes? grep's PCRE mode sucks anyway.
2. Point irrelevant if not using grep. Aside from that, your solution is broken, because the existence of the word "sage" anywhere will cause the line to fail to display.
3. The canonical form of an md5sum is 32 hexadecimal characters, but good point anyway, you're thinking outside the box and that's a good thing; sure, maybe it was base 32 or base 64 encoded instead of base 16. /mailto:(?!sage")/ it is, then.

And of course the real solution is to extract the e-mail fields using an HTML parser, and pipe through sort -u. As already stated, searching for a precomputed hash is a terrible! solution because there is a good chance that the input you use is different than that used to create the md5sum you're searching for. Capitalization chance is possible, although unlikely, that this might be different than advertised. Punctuation might be different -- are the quotation marks included? Line endings could certainly be different. Did you use echo or echo -n? If there is a newline, is it \r\n or \n?