Re: A simple notation, again

From: Bob Badour <>
Date: Mon, 16 Jul 2007 14:36:20 -0300
Message-ID: <469bac76$0$8868$>

David Cressey wrote:

> Using the notation [A B C] for <NOT> (A <AND> B <AND> C), etc.
> The following [ A [B]] means "A implies B" for Boolean algebra. What is
> the corresponding thing for Relational Algebra?
> Also, I'm trying to come up with a bracket notation for a "literal
> relation", like literals for simple datatypes like numbers and character
> strings.
> I'm toying with this:
> [["David" "Cressey" 1]
> ["Marshall" "Spight" 2]
> ["Bob" "Badour" 3]
> ["Jan" Hidders" 4]]
> This would represent a relation of order 3 and cardinality 4.
> What I don't like about this is that the binding between attribute values
> and attribute names is
> by position rather than by name, and in fact the attribute names don't even
> appear here. That's unacceptably bad. The symmetry is appealing, but it
> clearly needs improvement.

You omitted names entirely. You would have to extend the syntax to something like:
[[name="David" surname="Cressey" n=1]

  [n=2 name="Marshall" surname="Spight"]
  [surname="Badour" name="Bob" n=3]
  [name="Jan" surname="Hidders" n=4]]
Received on Mon Jul 16 2007 - 19:36:20 CEST

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