Re: Clean Object Class Design -- What is it?

>> How is the Lisp model of atoms and lists equivalent to or derived from
 any
>> branch of mathematics?
>
>I am not a Lisp expert, but I will go out on a limb and say that the Lisp
>model, like any logical or mathematical model, has primitive constructs and
>formal rules from which statements of truth or valid expressions can be
>derived. I have added comp.lang.lisp to the distribution in case there is
>some interest from those folks in answering your question.
>
>Why do we need to have a formal model from any particular branch of
>mathematics to be applied in the (decidedly formal) domain of computation?

We don't. We only need to have a useful formal model. Dr. Codd successfully applied a couple different branches of mathematics to the problem of database management. Over the last thirty years, they have certainly proved their worth.

What other formalisms has anyone applied to the problem of database management? How have they proved their worth?

>> Stealing heavily from Chris Date (and Hugh Darwen) again: Think of
 domains
>> (object classes) as the things we want to talk about and think of
 relations
>> as what we want to say about them. I think it is reasonable to want to
 make
>> statements regarding multiple things at once; hence, the tuple. I think
 it
>> is reasonable to want to make the same statement about different
>> combinations of things; hence, the relation.
>
>This sounds fine, except I am not sure why a distinction is made between
>domains and tuples.

Because they are fundamentally different things. One is a statement of fact and the other is a data type. Why do we make a distinction between nouns and sentences?

>It also seems reasonable to want to aggregate things at
>multiple levels and make statements on that basis. Why limit yourself to
 two
>levels?

I haven't limited myself to two levels. Domains can have arbitrary complexity including relation valued attributes. I can derive further statements of fact by combining multiple statements thereby extending a statements to additional aggregates. Received on Sat Aug 04 2001 - 19:52:08 CEST