[Zope3-dev] [DRAFT] local portlets and perspectives

[Michel Pelletier]

On Wed, 2005-08-24 at 22:25 -0400, zope3-dev-request at zope.org wrote:

> Subject: Re: [Zope3-dev] [DRAFT] local portlets and perspectives

<JM>
> > It is built on the notion of "Perspective" (see the link) and on the
> > idea of querying the catalog using triadic relations instead of joining
> > sets of query results based on dyadic predicates (such as with RDF).

<later said...>
> I think that Michel uses a triple BTree store in zemantic to index all
> three elements (subject, predicate, object), the idea here is the same
> except that relations can be triadic, (which gives 4 elements to index)
> this is why I index the relates with _indexRelates() and the predicate
> with _indexPredicate().

I didn't do a thorough analysis of your code, but I'm beginning to
suspect that the Peirce concept of "perspective" is identical to the RDF
concept of "context" and that the two models are possibly isomorphic.  

I read into the philosophy paper a bit more and got that a triple is a
statement of fact and not an actual realization without the fourth
perspective element which defines the context with which to apply that
fact.  If this is correct then that is essentially exactly what RDF
contexts are for.

I don't mean to imply that it invalidates your experiments!  Your code
is interesting and it may indeed have some feature benefits over rdflib.
I just mean that I suspect, with very little analysis on my part mind
you, that they may be similar if not eventually identical models.

> Also most importantly the elements of the relation are also indexed as
> one unique tuple, which means that I do can a direct lookup in the
> catalog if *all* the elements are specified during the query.

ditto with rdflib, a context as well as a triple pattern can be passed
to the add/remove/query methods of a graph, although this context
information is optional.

-Michel