Re: Relations contain Objects
Date: Thu, 13 Jun 2002 21:45:11 -0400
Message-ID: <tWbO8.266$eR3.41253974_at_radon.golden.net>
"James" <jraustin1_at_hotmail.com> wrote in message
news:a6e74506.0206131735.26c916b2_at_posting.google.com...
> > Silly, you already know that objects equals domains.
>
> An object isn't equivalent to the domain or range.
> An object is equivalent to an element in either domain or range.
Object class equals domain.
Object value equals element in domain.
> > Unfortunately, that does not resemble a relational definition of the
term.
>
> Although my definition was rather simple it does state the essense of
> what a relation is: a set of related things.
Unfortunately, it oversimplifies.
> > Specifically, a relation has a header consisting of a set of N named,
typed
> > attributes and a body consisting of a set of N-dimensional tuples with a
> > value corresponding to each of the named, typed attributes.
>
> Let N = 1
If I have a relation variable of 1 dimension, I can quickly and easily derive a 2 dimensional relation using cartesion product.
What is your product's equivalent operation?
> Although each element has a type, there is no need to consider it at
> the logical level. Is there?
Type is logically very important!
> > They are the same as mathematical relations.
> > Each of the values in every tuple is an object in an OO sense.
>
> Although a tuple has a type, is there is no need to consider it at the
> logical level?
Type is logically very important! For instance, two values of different type cannot be equal and equality is an important logical concept. Received on Fri Jun 14 2002 - 03:45:11 CEST