Relationship between real-world phenomenon and feature document

[jechterhoff]

Description

Let us assume that the representation of an INSPIRE feature in INSPIRE RDF schemas was split in two resources: 1) containing information about the real-world phenomenon, and 2) containing information about the feature document itself (feature metadata, see issue #22).

When two persistent URIs are assigned for each resource, one for the INSPIRE feature document and one for the real-world phenomenon, it would be useful to link the two resources. It has been proposed to use rdfs:isDefinedBy and foaf:isPrimaryTopicOf:

• :realworldobject rdfs:isDefinedBy :featuredocument.
• :featuredocument foaf:primaryTopic :realworldobject.

The use of rdfs:isDefinedBy follows the convention used in "Cool URIs for the Semantic Web". The use of foaf:primaryTopic for the inverse statement seems to be frequently used in the linked data world; a side effect is that :featuredocument is a foaf:Document, but this should be appropriate.

Whether or not this proposal is appropriate and sufficient needs to be determined. In general, guidance is needed on how a relationship between two resources, one for the real-world phenomenon and one for the feature document, should be established.

[jechterhoff]

The Spatial Data on the Web working group (SDW WG) discusses the addition of another use case and requirement, which would be about finding a way to express that data based on different models are about the same real-world spatial object [1]. (Update 2016-07-19: a new use case has been added)

The problem is that there is no way to express that both batches of data (i.e., resources) are about the same subject and that the two batches of data could complement each other. Properties like owl:sameAs, rdfs:seeAlso, umbel:isLike, bbccore:sameAs and http://schema.org/about are regarded as insufficient or inappropriate.

Discussion in the SDW WG indicates that one or more new properties could be defined.

In report D.EC.2.1 from the study on RDF and PIDs for INSPIRE (prepared as part of the ARE3NA activity), a new property "gcm:models" is used. Such a generic property might be a suitable solution, especially if it does not have any unnecessary implications (like having a specific class as domain or range).

Edit (17 Jan 2017): Should an INSPIRE base ontology define such a "models" property? Without a domain restriction, that property could be used in all RDF resources that represent INSPIRE spatial objects.

[1] https://lists.w3.org/Archives/Public/public-sdw-wg/2016Jul/0031.html

[jechterhoff]

Some considerations on foaf:primaryTopic, in case that the INSPIRE feature was not split in two resources:

• It is a functional property, meaning that a feature can only have one primary topic. If a feature had multiple foaf:primaryTopic declarations, then a reasoner would have to assume that the objects (in this case: the real-world phenomena) are all equal. This may or may not be desirable. Example: an individual abstracts a "monastery". The real-world phenomenon could just be the monastery building, but it could also be the building including surrounding land (that belongs to the monastery). Are these real-world phenomena equal? If they are not, should the individual not be able to reference them both?
• The domain of foaf:primaryTopic is foaf:Document. A foaf:Document is owl:disjointWith foaf:Organization and foaf:Project. A feature that used foaf:primaryTopic could then not be a subclass of foaf:Organization even though in some cases this might be desirable.

Ideally, a property to represent the relationship between a real-world phenomenon and a feature does not have these implications.

[jensscheerlinck]

For the buildings theme, the way it is currently encoded in RDF, the two would coincide. For example the bu-base:Building is a subClassOf the bu-base:AbstractBuilding, where the AbstractBuilding describes the feature document/metadata and Building contains properties that describe the real-world phenomenon.

As such, I believe the use of bu-base:Building would mean that 1) It inherits all attributes of bu-base:AbstractBuilding 2) There is no separate instance of bu-base:AbstractBuilding for this real world object as the instance of bu-base:Building would represent both the real-world phenomenon and its metadata. 3) No explicit relationship between the two is needed.

bu-base:AbstractBuilding
        a                      owl:Class ;
        rdfs:isDefinedBy       <http://inspire.ec.europa.eu/featureconcept/AbstractBuilding> ;
        rdfs:label             "Abstract building"@en ;
        rdfs:subClassOf        bu-base:AbstractConstruction , gsp:Feature ;
        iso19150-2:isAbstract  true ;
        skos:definition        "Abstract spatial object type grouping the common semantic properties of the spatial object types Building and BuildingPart."@en .

bu-base:Building  a            owl:Class ;
        rdfs:isDefinedBy       <http://inspire.ec.europa.eu/featureconcept/Building> ;
        rdfs:label             "Building"@en ;
        rdfs:subClassOf        bu-base:AbstractBuilding , gsp:Feature ;
        iso19150-2:isAbstract  true ;
        skos:definition        "A Building is an enclosed <b>construction </b>above and/or underground, used or intended for the shelter of humans, animals or things or for the production of economic goods. A building refers to any structure permanently constructed or erected on its site."@en .

[jechterhoff]

The draft vocabularies do not differentiate between properties that describe the real-world phenomenon and properties that contain feature metadata (see also http://inspire-eu-rdf.github.io/inspire-rdf-guidelines/#ref_instance_cr_considerations_on_spatial_objects).

@jensscheerlinck: It's not clear to us if your comment contains an actual proposal.