Often the browse application we need to treat entities with the same CRM class differently. For instance, there are many man-made objects, but only some of them are works of art.
The AAC's best practice is to use the
P2 has type predicate to add clarifying details.
aac:young_women_picking_fruit a crm:E22_Man-Made_Object ; crm:P2_has_type aac:work_of_art . aac:work_of_art a E55_Type ; skos:prefLabel "Work of Art" .
When linking to an external vocabulary as a type, also include
skos:inScheme to indicate the source of the term.
aac:young_women_picking_fruit a crm:E22_Man-Made_Object; crm:P2_has_type aat:300033618 . aat:300033618 skos:inScheme aat: ; skos:prefLabel "Painting" .
It is not necessary to explicitly type the external vocabulary as an
E55_Type. If needed, this can be inferred through the use of the
We need to decide if we're subclassing entities or adding types.
aac:young_women_picking_fruit a crm:E22_Man-Made_Object; crm:P2_has_type aac:work_of_art.
aac:young_women_picking_fruit a aac:work_of_art. aac:work_of_art rdfs:subClass crm:E22_Man-Made_Object.
(From Rob Sanderson)
Are we doing Linked Open Data for Museums, using CRM as one of the ontologies, or are we doing CIDOC-CRM with its Linked Open Data serialization? If we're doing the former, that CRM happens to have P2_has_type doesn't mean we need to use it, but if we're doing than the latter, we would.
Regular Linked Data would use subClassing and rdf:type for classes (thus at the ontology level), whereas the CRM projection into RDF builds it in to the regular set of predicates (thus at the individual instance level). My preference is for the latter, rather than creating our own little world apart from everyone else. So I would avoid P2 and E55.
To then go to the question, if we had actual subclasses, we would refer from the class definition in the ontology to the AAT term that matches.
This means a huge, badly defined and ever-changing class hierarchy. Check the AAT Objects facet (which is fully half of AAT, some 21k concepts). Trace some of the multi-parented hierarchies. Is a watercolor a subtype of painting, or is that a technique? I'd rather leave it to the terminologists to decide questions like this.
As opposed to a huge, badly-defined and ever-changing concept hierarchy that’s at least 2 steps removed from the actual object?
Otherwise all we need is E1_Entity and just point at the AAT concept for Man Made Object. The current approach says CRM is the only ground truth, and everything else is a local idea with some relationship to a concept in a big old pool of stuff. A not unreasonable and pretty well known big old pool of stuff, of course :)
I'll let the subclassing point go, even though I think it's terrible practice to reimplement classes as concepts.
In ResearchSpace I found that we needed to mark the "top-level" searchable E22 (artworks) somehow. We had other E22, e.g.: