Re: Generalised approach to storing address details

On Dec 11, 11:19 pm, paul c <toledobythe..._at_oohay.ac> wrote:
> Neo wrote:...
>
> >>You think that RM can't handle hierachies after I answered your demand on the *Brothers and Sisters* thread with a simple structure that perfectly met your criterias?
>
> > It is not that RM can't handle hierarchies, ...I would like to know how the RM handles hierarchies, without the aid of
> a builtin such as TTM's TCLOSE that is essentially outside the scope of
> the RM (eg., it seems to me that it does a transformation that can't be
> couched in fundamental RM terms.)

Hi Paul. Remember that hierarchies are just a subset of the big picture given they are composed of binary relations. Given the RM is a generalized model, handling n-ary relations, surely the question is /why would it/ provide support for the special case of diadic relationships? If RM natively supported transitive operation would it still be an algebra? And if it did what would applying transitive closure to a ternary relation mean exactly?

When we draw a hierarchy on paper we are constructing a handy shortcut (google hasse diagrams for their generalization), and if we enumerated the underlying relation mathematically we would end up listing _all_ of the ancestry ordered pairs, not just the local ones. So I reply mu and unask your question. The RM can represent hierarchy more than happily, but it is not imo the responsibility of a generalized data model to handle the extra idiosyncracies and shortcuts of binary relations specifically.

>
> p
Received on Tue Dec 12 2006 - 13:44:20 CET