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  1. #1
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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

  2. #2
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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 technology-aware members.

    Check out Tuple Calculus and First Order Logic for a good start.

    -PatP

  3. #3
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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 first-order 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 first-order 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

    Quote Originally Posted by Pat Phelan
    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 technology-aware members.

    Check out Tuple Calculus and First Order Logic for a good start.

    -PatP

  4. #4
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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

  5. #5
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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

    Quote Originally Posted by Pat Phelan
    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

  6. #6
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    Quote Originally Posted by tbeer
    And unfortunately I couldn't find adequate literature up to now.
    i thought dissertations were supposed to contain original work



    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
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  7. #7
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    Really?

    Thanks for your help, I will check out the mentioned usegroup.

    Tom

    Quote Originally Posted by r937
    i thought dissertations were supposed to contain original work



    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

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