Faceted Search

I don't know if this is something new, it just seems it was useful for the
kind of interface I was looking for. I was just wondering what would be the
best way to facilitate browsing and search in the application demo I'm
building that renders RDF / Semantic Web contents. I've figured out there
must be a tree hierarchy of categories, roles and instances of data to
which adhere the incoming data parsing so having a common denominator for
different input structures.

Having this structures, browsing through the tree of data, an item (leave
or node) could be 'picked up' as a facet. For example, if the scenario is
"Car Rental" as a category, "Car Model" and "Rental City" as roles and many
models of cars and many cities as instances, what if I could pick a car
model, a city or both and press "Aggregate" and this resulting in root
categories for each specific car rental ("Car Rental 1", "Car Rental 2",
etc) with its roles populated with the corresponding criteria values (the
city corresponding to "Car Rental 1" given its car, etc).

Maybe this sounds dumb. But the question is: how difficult would be to
build such a filter criteria using only RDF datasources. RDF statement
resources are not individualized by their occurrences. An RDF resource is
the same regardless which statements it occurs. And, although I've found a
way to individualize occurrences of, for example, Car Rental(s), I can't
find the way yet to correlate this instances with the instances of their
roles.

Also, I'm restricting my mappings (ontology processing output) to three
levels depth, which seems arbitrary. I could not restrict the graph to any
depth. But I'll keep trying a while with this arrangements. It seems
attractive the correlation of categories, roles and instances with some of
the concepts in the DCI programming model (
https://en.wikipedia.org/wiki/Data,_context_and_interaction) which could
allow for a model driven focused approach of building the client
application, again with the ontology 'common factors' concept in mind.

Source, examples and the demo web application are available in the project
web page:

http://cognescent.blogspot.com
http://sourceforge.net/projects/cognescent/

Regards,
Sebastian