Re: Role of the Ontology and Expressivity - to discuss on telcon

> This week I commented on the role of the ontology [1] where we should
> consider that we are mapping to the following:
>
>    - existing domain ontology (FOAF, SIOC, etc)
>    - a putative ontology (automatically generating the ontology from the
>    schema/DDL)
>    - a federated ontology: combining different ontologies
>
>
> Eric initially manifested the need to talk about the expressivity [2]. If
> I
> understand correctly the issue of the expressivity is being presented as
> "DIRECT - Recapulating Relational Structure" [3] and TRANSFORM -
> Non-isomorphic transformation [4].
>
> I'm honestly a bit confused with both of these requirements, but this is
> my
> take on them. Eric, please correct me if I'm wrong:
>
> DIRECT: What I understand is that you could essentially automatically
> generate RDF triples (a graph) from the relational data. The top image
> shows
> a graph of relational data and the bottom image shows how the previous
> graph
> can be exposed as RDF (a graph) and it is equivalent (isomorphic) to the
> relational data graph.

We may want to add sentence "This would be useful in directly mapping
relational data to RDF and then dumping the entire database as linked
data."

>
> TRANSFORM: In this section you have taken the previous relational data
> graph
> and put it into the graph structure of two different ontologies. You show
> that if you compare the relational data graph with the two graph
> structures
> of the two different ontologies, then the graphs are different
> (non-isomorphic).

You could just also say "We should allow changes to the RDF automatically
generated from the relational data so that the RDF does not have to be
isomorphic to the graph." but if people feel more comfortable with the use
of domain ontology wording that's fine with me.

>
> IF I UNDERSTOOD THIS CORRECTLY... then
>
> What I was mentioning initial (putative ontology and domain ontology) is
> directly aligned to what Eric is presenting. Essentially, creating a
> putative ontology directly from the sql ddl is equivalent to the DIRECT
> requirement and mapping the rdb schema to an existing domain ontology is
> the
> TRANSFORM requirement. Therefore, I propose that this needs to be
> reworded.
> Honestly, it is very difficult to understand and I think the semantic web
> and database community would both understand that we are talking about
> mapping to an ontology.
>
> Sometimes there doesn't exist a domain ontology that I would like to map
> to,
> therefore I will just use the DIRECT approach. This is what I consider
> "direct mapping", therefore we are totally aligned in our thoughts. On the
> other hand, you do want to map to existing domain ontologies. These
> mappings
> will have a higher level of complexity.
>
> In conclusion, we I propose that we present these requirements as:
>
> The mapping language should be able to expose the relational data as RDF
> without considering a domain ontology
>
> The mapping language should be able to express the mapping between the
> relational schema and a existing domain ontology

+1. If the database community feels better about using "ontology" here
rather than stem and interface graph or isomorphic and non-isomorphic, I'm
all for it, although we should note what it means perhaps using the
isomorphic/non-isomorphic terminology.


Sounds like a formal proposal to me..
>
> [1]
> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2010Apr/0059.html
> [2] http://www.w3.org/2001/sw/rdb2rdf/wiki/Draft_of_Use_Cases#Expressivity
> [3] http://www.w3.org/2001/sw/rdb2rdf/use-cases/#DIRECT
> [4] http://www.w3.org/2001/sw/rdb2rdf/use-cases/#TRANSFORM
> Juan Sequeda
> +1-575-SEQ-UEDA
> www.juansequeda.com
>

Received on Tuesday, 27 April 2010 04:20:46 UTC