Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]

vc wrote:
>
> What's the (a) formalism for the FDM comparable to the RM (the FDM
> structure/the FDM algebra/FDM constraint definitions). Daplex does not
> quite cut it as an 'algebra'.

Why not? Because it has operations with side effects? That can be easily fixed. You want a logic? Use Description logics.

> Now, IFO, as far as I remember, deals only with the structural part,
> namely, directed graphs representing 'atomic objects', 'constructed
> objects', etc. No algebra/data manipulatation and no constraint
> definition was suggested at the time.

That was done in later work such as "Object identity as a query language primitive" by Abiteboul and Kanellakis.

> Do not know about the rest of the bunch but wonder whether the triple
> <structure, algebra, constraints> has been defined for at least one of
> the abbreviations cited.

LDM (the Logical Data Model) had a logic defined with it.

> I tried to read one of the articles you've referenced
> (http://www.orm.net/pdf/ER96.pdf, "Conceptual query language"), but
> quickly stumbled over the words "semantic" and "conceptual".

:-) Yeah, ORM people like to use those words a lot. I wouldn't worry too much about it. You can understand the query language w/o understanding what those words exactly mean.

>>No. In ORM NOLOTs are abstract. It is more correct to say that the RM is
>>basically ORM restricted to LOTs. A very grave and crippling restriction
>>indeed.

That there is no value representation associated with non-lexical objects.

• Jan Hidders