Re: MV Keys

From: Brian Selzer <brian_at_selzer-software.com>
Date: Wed, 08 Mar 2006 18:49:45 GMT
Message-ID: <dHFPf.45417$Jd.38341_at_newssvr25.news.prodigy.net>


"vc" <boston103_at_hotmail.com> wrote in message news:1141824160.347616.85480_at_i40g2000cwc.googlegroups.com...
>
> Brian Selzer wrote:
> [...]
>> "x is 2" is a sentence; "y is 3" is a sentence.
>> "x is 2 and y is 3" is also a sentence.
>
> You are confused. "x is 2" is not a sentence in the contex of FOL.
> It's a predicate with a free variable which will become a sentence if
> you substitute a constant for x.
>

It isn't? So, what you're saying is the statement, "Joe is 30 years old" is not a statement in FOL? As I said, I'm not a logician, so I don't speak their jargon. I guess I don't speak their language either.

If E(x in X)(x = 2) and E(y in Y)(y = 3) are predicates, would a predicate with an variable that belongs to the cartesian coordinate domain be a statement in second order logic? I'm not being facetious, I'd really like to know.

>
>>Thus a tuple in a relation R{A, B, C} is the
>> set of propositions {A has value 3, B has value 7, C has value 2}. The
>> tuple itself also has a truth value, "A has value 3 and B has value 7 and
>> C
>> has value 2." which is a proposition in conjunctive normal form.
>
> You are confused even more. A relation is simply an interpretation of
> some predicate (which is an element of a FOL language). A tuple is an
> element of such relation.
>
So, you're saying that an element of a relation doesn't have a truth value? Received on Wed Mar 08 2006 - 19:49:45 CET

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