Re: Inverse Regex Library?
Re: Inverse Regex Library?
- Subject: Re: Inverse Regex Library?
- From: "Vincent E." <email@hidden>
- Date: Thu, 17 Jul 2008 18:18:18 +0200
It could also have been:
Word[1247]?[1235789]
or
Word[124578][13579]?
Conclusion:
Don't think a reliable solution for this can exist. It's just too few
information to detect the right pattern.
Even as a human being I'm actually not even 75% sure what's the right
pattern for these words. How should a computer then?
On Jul 17, 2008, at 5:18 PM, Erik Buck wrote:
You ask an interesting computer science question (that's unrelated
to Cocoa).
Surely the following sequence of words would produce Word[1-9]{1,2}
instead of Word[0-9]{1,2} because there is no representative 0 in
the sample ?
"Word1"
"Word2"
"Word5"
"Word8"
"Word11"
"Word19"
"Word23"
"Word45"
"Word77"
Anyway, I think this is an unsolvable problem, and I might start
with an attempted proof of its unsolvability rather than a
solution. Lots of artificial intelligence and/or statistical
pattern recognition could be applied to achieve reasonable results
in general cases. If you have specific cases like letters followed
by numbers you might use a lexer and parser like flex/bison.
Have you considered a "perfect hash" ? What are you really trying
to achieve ?
http://en.wikipedia.org/wiki/Perfect_hash_function
http://www.nist.gov/dads/HTML/minimalPerfectHash.html
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