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Extend examples
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Expand Up @@ -4,7 +4,7 @@ title: CIDOC-CRM in RDF Application Profile

## Background and Motivation

The [CIDOC Conceptual Reference Model (CRM)](https://www.cidoc-crm.org/) is a conceptual data model used in the cultural heritage domain. The [Resource Description Framework (RDF)](https://www.w3.org/TR/rdf11-concepts/) is a graph-based data format. Both CRM and RDF have been created independently for integration of information. RDF is a good fit to express CRM in data and it has been used to do so. The expression of CRM in RDF is not trivial though, so some guidelines are needed. This document is going to provide an application profile to best use CRM in RDF for integration with other data in RDF. The document is going to be compared and aligned with similar recommendations such as @Doerr2020.
The [CIDOC Conceptual Reference Model (CRM)](https://www.cidoc-crm.org/) is a conceptual data model used in the cultural heritage domain. The [Resource Description Framework (RDF)](https://www.w3.org/TR/rdf11-concepts/) is a graph-based data format. Both CRM and RDF have been created independently for integration of information. RDF is a good fit to express CRM in data and it has been used to do so. The expression of CRM in RDF is not trivial though, so some guidelines are needed. This document is going to provide an application profile to best use CRM in RDF for integration with other RDF data within NFDI4Objects. The document is going to be compared and aligned with similar recommendations such as @Doerr2020.

The document is managed in a git repository at <https://github.com/nfdi4objects/crm-rdf-ap>. Contributions and feedback is very welcome!

Expand All @@ -24,7 +24,30 @@ CRM defines abstract types of entities (CRM classes) such as events, measurement

The CRM classes [E61 Time Primitive], [E94 Space Primitive], and [E95 Spacetime Primitive] are both subclasses of [E59 Primitive Value] and of [E41 Appellation], so the latter can be used when a mapping to established RDF data types is not applicable.

- instances of [E61 Time Primitive] are expressed as RDF literals of type `xsd:date`, `xsd:time`, `xsd:dateTime`, or `xsd:dateTimeStamp` if applicable. More complex time values should be expressed using the [Extended Date/Time Format (EDTF)](https://www.loc.gov/standards/datetime/) but there is no established method to express EDTF values in RDF yet.^[See <https://periodo.github.io/edtf-ontology/> for a draft.]
- instances of [E61 Time Primitive] and [E52 Time-Span] eare expressed as RDF literals of type `xsd:date`, `xsd:time`, `xsd:dateTime`, or `xsd:dateTimeStamp` if applicable. More complex time values should be expressed using the [Extended Date/Time Format (EDTF)](https://www.loc.gov/standards/datetime/) but there is no established method to calculate with EDTF in RDF yet.^[See <https://periodo.github.io/edtf-ontology/> for a draft.] CRM includes its own classes and properties to model more complex temporal values so this has not been decided yet.

~~~ttl
@prefix edtf: <http://id.loc.gov/datatypes/edtf/>
@prefix unit: <http://qudt.org/vocab/unit/> .
<x> dc:date "2000?"^^edtf:EDTF .
<TitanticSinking> a crm:E81_Transformation ;
crm:P124_transformed <RMSTitanic> ;
crm:P123_resulted_in <TitanticWreck> .
crm:P4_has_time-span
"1912-04-15"^^xsd:date ,
[
a crm:E52_Time-Span ;
crm:P82_at_some_time_within "1912-04-15"^^xsd:date
] ;
# TODO: add exact time of sinking (02:38–05:18 GMT)
crm:P191_had_duration [
crm:P90_has_value 160 ;
crm:P91_has_unit unit:MIN
]
.
~~~
- instances of [E94 Space Primitive] should be expressed using [GeoSPARQL] Ontology as instance of `geo:hasGeometry`, compatible with various geographic data formats (WKT, GeoJSON, GML...).^[See also CRM Geo draft at <http://www.cidoc-crm.org/extensions/crmgeo/>, defining superclasses of `geo:Geometry`.] CRM Property [P168 place is defined by] should be expressed with RDF property `geo:hasGeometry`. CRM Properties [P171 at some place within], and [P172 contains] can be used as RDF properties to link places ([E53 Place]) to outer and inner geometries but `geo:hasBoundingBox` and `geo:hasCentroid` should be preferred, if applicable.
Expand All @@ -48,6 +71,7 @@ The CRM classes [E61 Time Primitive], [E94 Space Primitive], and [E95 Spacetime
[P168 place is defined by]: http://www.cidoc-crm.org/cidoc-crm/P168
[E52 Time-Span]: http://www.cidoc-crm.org/cidoc-crm/E52
[E53 Place]: http://www.cidoc-crm.org/cidoc-crm/E53
[E41 Appellation]: http://www.cidoc-crm.org/cidoc-crm/E41
[E59 Primitive Value]: http://www.cidoc-crm.org/cidoc-crm/E59
Expand Down Expand Up @@ -93,14 +117,16 @@ Defintion of instances of [E58 Measurement Unit] should be avoided but either ta
Don't use [E42 Identifier] for URIs if these URIs are meant to identify an RDF resource. If a resource happens to have multiple equivalent URIs, choose a preferred URI and use `owl:sameAs` to record aliases.

~~~ttl
<http://www.wikidata.org/entity/Q3018259> a crm:E18_Physical Thing ;
owl:sameAs <http://kbpedia.org/kko/rc/RMS-Titanic-TheShip> .
<RMSTitantic> a crm:E18_Physical Thing ;
owl:sameAs
<http://www.wikidata.org/entity/Q3018259> ,
<http://kbpedia.org/kko/rc/RMS-Titanic-TheShip> .
~~~

instead of

~~~ttl
<x> a crm:E18_Physical Thing .
<RMSTitanic> a crm:E18_Physical Thing .
crm:P1_is_identified_by
[ a crm:E42_Identifier ;
crm:P190_has_symbolic_content "http://www.wikidata.org/entity/Q3018259" ] ,
Expand Down

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