Re: Stored fields ordered left to right

Dawn M. Wolthuis <dwolt_at_tincat-group.com> schrieb:
> So, where I have seen no instances that cannot be modeled equally well
> with functions as with relations, I have seen many times when a
> flexible function is a much better way to model the propositions.
>
> Take some example propositions:
>
> Hope has a cat named Geneva and a dog named Rugby.
> Shanna has no pets, but did have a dog named Monte who died in 2002.
>
> Given only these statements, I might immediately come up with something like
> this:
>
> a function named PEOPLE and the assignment of an arbitrary (or sequentially
> assigned) id for each person
> PEOPLE("12345") = { "Hope", { ("cat", "Geneva", NULL) , ("dog", "Rugby",
> NULL)} }
> PEOPLE("12346") = ( "Shanna", { ("dog", "Monte", "2002") } }

This is not modeling, because all you've done is associate some lists with each person, without any formal way to reason about what the lists MEAN. I could just as well "model" the first proposition as:

CATS("Geneva") = { {("owner", "Hope")} } etc.

        or even
PEOPLE("12345") = { "has a cat named Geneva and a dog named Rugby" }

Any extra flexibility you get is by delegating more of the semantics/interpretation to the clients of the database. Received on Wed Jan 14 2004 - 07:53:33 CET