Re: more on delete from join

From: Marshall <>
Date: Thu, 3 Sep 2009 07:11:39 -0700 (PDT)
Message-ID: <>

On Sep 2, 9:50 pm, "Mr. Scott" <> wrote:
> "Marshall" <> wrote in message
> <quote>
> I guess I see what you mean, but strictly speaking it doesn't seem
> to fit the definition. In abductive reasoning, one knows a -> b, and
> b, but one doesn't know that it was in fact a that implied b. Whereas
> with a view, we do know.
> </quote>
> Do we?
> For an insert into a union view, one knows a -> c \/ b -> c and c, but one
> doesn't know whether it was in fact a or b or both that implied c.
> For a delete from a join view, one knows ~a -> ~c \/ ~b -> ~c and ~c, but
> one doesn't know whether it was in fact ~a or ~b or both that implied ~c.

The mixing of propositional vs. predicate logic terminology, along with the
use of terms that were not intended to describe imperative operations, is too unclear for me to disentangle. If you want to use these terms these ways, I can't stop you, but I don't agree that it's good usage of the terms. But ultimately, what terms we use is of little importance;
it's the semantics that is important. If you wanted to respond to some of my semantic points, that might be interesting.

Marshall Received on Thu Sep 03 2009 - 16:11:39 CEST

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