On 07/04/06, Steven Perry <smperry@ku.edu> wrote:

Hi Markus,

This is analogous to the example that Rob and I showed at the Madrid
TAPIR meeting with relationships between records representing people and
records representing the department(s) they work in.  The issue in both
cases is that, with complicated data of multiple types, global concepts
don't always provide enough information for one to answer the kinds of
queries they might like.  To do queries like these, its our feeling that
you have to know information about the different types of objects whose
relationships you want to examine (in other words you have to know the
domain of each property).

Just as an aside, most triple stores that are implemented over databases
process queries using the second approach you outlined below (repeated
self joins on the triple table).  The beauty of this approach is that,
with minor modifications, you have the ability to represent combinations
of ANDs and ORs which allow you to distinguish between mandatory and
optional match conditions independently of what you want to return from
the query.

I'm also looking forward to talking about this and other issues in
Edinburgh; see you next week.

-Steve

Döring, Markus wrote:
> Hello,
> I had a talk with Gregor and the others this week to find out whether TAPIR is suitable for SDD. Apart from the known recusive issue we were concerned about one major search problem I would like to introduce you to:
>
>
> Imagine a simple concept "ontology" with a specimen linked to identifications with a taxon-name and an identifier (person).
>
> If I want to do a combined search on the identifier AND the taxon name I actually have 2 ways of asking the query.
>
>
> 1) use the same identification object to do the AND. In SQL this would be:
>
> SELECT * FROM specimen s JOIN identification i ON xxx WHERE i.taxon_name = "Abies alba" AND i.identifier= "Markus"
>
>
>
> 2) dont require the identifier to have done the identification of the required name, but to be an independent constraint. In SQL you would use an alias of that table:
>
> SELECT * FROM specimen s JOIN identification i1 ON xxx JOIN identification i2 ON xxx WHERE i1.taxon_name = "Abies alba" AND i2.identifier="Markus"
>
>
>
> This gives different results.
> And it is a common query in SDD when searching on characters.
>
> As far as I can see TAPIR cannot handle this, as a TAPIR request doesnt know about the relations between concept. The entities, classes whatever you would like to call it. A loose list of independent concepts really doesnt seem to work. We might need to know about the class relations/multiplicity at least on a high level. In general this could be taken from an XML Schema as well as OWL, RDFS or alike.
>
> Or we could prescribe a TAPIR service what to do in such cases. If a complex AND query is received we could prescribe to resolve that query in way #1 (i think its the more common intention). But then noone would be able to ask questions of type2.
>
> Maybe we could discuss this further in the TAG meeting, Session 4: Integration of Existing Technologies with a Core Ontology?
>
> I do not have an answer yet to that question, but I wanted to spread the problem before the TAG meeting.
>
>
> Looking forward to meet you all in Edinburgh,
> Markus
>
>
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