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071008, 16:29 #1Registered User
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 Jul 2008
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 Innsbruck / Austria
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Relational Calculus, which subset of FOL is supported?
Hi all!
It is often stated that relational calculus is a subset of first order logic.
Which "subset" of FOL is supported by the relational calculus in detail? Where can I found some literature to cite?
I really appreciate your help.
Best regards,
Tom

071008, 18:06 #2Resident Curmudgeon
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Wikipedia is your friend, although some truly demented educational institutions (grossly dysfunctional ones at that) refuse to allow Wikipedia citations. Note that encyclopedias had similar problems for almost fifty years after they became available to the public, so this may not change until the old crew at the institution are eventually replaced with somewhat more technologyaware members.
Check out Tuple Calculus and First Order Logic for a good start.
PatP

071108, 01:06 #3Registered User
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 Jul 2008
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Hi Pat!
I know the wikipedia, wapedia etc. articles
http://wapedia.mobi/en/Relational_algebra
http://en.wikipedia.org/wiki/Relational_algebra
stating:
"Codd's algebra is not in fact complete with respect to firstorder logic, he restricted the operands to finite relations only and also proposed restricted support for negation (NOT) and disjunction (OR)"
"Relational algebra actually corresponds to a subset of firstorder logic that is Horn clauses without recursion and negation."
I also know Codd's (original) paper from 1970 (unfortunately I don't have the original one from 1969).
What I'm looking for, is a more "serious comparison" of relational algebra and FOL (i.e. expressive power, limitations).
Best regards,
Tom
Originally Posted by Pat Phelan

071108, 08:27 #4Resident Curmudgeon
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I assume that you are trying to do some homework, I can't think of another reason for asking this question.
Try reading the articles that I cited. While they don't give you a presentation that you can hand in, they give you enough information that you should be able to answer the question as well as enough citations to go find more specific details if you need those details.
PatP

071108, 08:38 #5Registered User
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 Jul 2008
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No, you are wrong ;)
I'm currently writing down my dissertation, and for my "foundations" section I need the information about the relationship between FOL and Relational Algebra.
And unfortunately I couldn't find adequate literature up to now.
Tom
Originally Posted by Pat Phelan

071108, 08:52 #6SQL Consultant
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 Apr 2002
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Originally Posted by tbeer
anyhow, you're probably in the wrong forum... 99.937% of the members here are practitioners, not theorists
but hey, that reminds me, you will surely get wonderful feedback in comp.databases.theory

071108, 09:12 #7Registered User
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 Jul 2008
 Location
 Innsbruck / Austria
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Really?
Thanks for your help, I will check out the mentioned usegroup.
Tom
Originally Posted by r937