Re: Relation Definition

Jan,

>> For the authorative ones that real database theorists use see the
>> definitions in the Alice book:

I apologize if I missed the obvious. But where in the Alice book did you find the definition you just stated?

>> No. Of all the formal definitions of the relational model I have seen his
>> is probably the clumsiest.

In what way does your definition any less clumsy than what is in Date's book? Date defines a relation as having a header consisting of a set of n named, typed attributes and set of n-dimensional tuples where each dimension value of the tuple corresponds to a named, typed attribute.

Offering formalism for relations based on infinite disjoint sets of symbols -- attributes, constants, variables and relation names by themselves offer no practical use unless a real world interpretation is assumed. Thus in the simplest possible terms, rows represent real world entities, column values represent their properties and relational operations answer the questions about them. Given Date has an entire career explaining how theory can be practical and his explanations occasionally informal, I see nothing clumsy in his definition.

What does your definition additionally offer w.r.t Date's definition? Meanwhile, I can see you ignored the typed perspective altogether though.

-- 
Anith