Add qualified familial relationships

[acka47]

As already written in #424, we should think about how to add the qualified familial relationships to the JSON data. See also this issue for background: deutsche-nationalbibliothek/gnd-ontology#5

@moinluk asked about it today on fedi, see https://openbiblio.social/@moinluk/116238817833094089.

gndo:hasRelation

It seems that this is used redundantly to the specific agrelon relation properties. Example (snippet):

<https://d-nb.info/gnd/118540238> skos:exactMatch thesoz:concept_10045849;
  gndo:originalScriptNameOfThePerson "ゲーテ, ヨハン・ヴォルフガング・フォン"@ja;
  gndo:familialRelationship <https://d-nb.info/gnd/118695940>;
  agrelon:hasParent <https://d-nb.info/gnd/118695940>;
  gndo:hasRelation _:node1iqff71p6x165539 .

_:node1iqff71p6x165539 agrelon:hasParent <https://d-nb.info/gnd/118695940>;
  a gndo:Relationship .

<https://d-nb.info/gnd/118540238> gndo:familialRelationship <https://d-nb.info/gnd/118540246>;
  agrelon:hasParent <https://d-nb.info/gnd/118540246>;
  gndo:hasRelation _:node1iqff71p6x165540 .

_:node1iqff71p6x165540 agrelon:hasParent <https://d-nb.info/gnd/118540246>;
  a gndo:Relationship .

<https://d-nb.info/gnd/118540238> gndo:familialRelationship <https://d-nb.info/gnd/11871791X>;
  agrelon:hasSibling <https://d-nb.info/gnd/11871791X>;
  gndo:hasRelation _:node1iqff71p6x165541 .

_:node1iqff71p6x165541 agrelon:hasSibling <https://d-nb.info/gnd/11871791X>;
  a gndo:Relationship .

<https://d-nb.info/gnd/118540238> gndo:familialRelationship <https://d-nb.info/gnd/118795163>;
  gndo:hasRelation _:node1iqff71p6x165542 .

_:node1iqff71p6x165542 gndo:familialRelationship <https://d-nb.info/gnd/118795163>;
  gndo:functionOrRoleAsLiteral "Schwager";
  a gndo:Relationship .

<https://d-nb.info/gnd/118540238> gndo:familialRelationship <https://d-nb.info/gnd/118628011>;
  agrelon:hasSpouse <https://d-nb.info/gnd/118628011>;
  gndo:hasRelation _:node1iqff71p6x165543 .

_:node1iqff71p6x165543 agrelon:hasSpouse <https://d-nb.info/gnd/118628011>;
  a gndo:Relationship .

I think, we should leave this out from now and open a separate ticket for this.

[acka47]

EntityFacts chose an interesting approach: It links to the person a relationships exists to and adds a relationship label to the object. This would be incorrect in RDF terms as the relationship label is assigned to the person, not the relation. To mitigate this the property relationship is not part of the JSON-LD context and, thus, omitted when the data is transfomred e.g. into Turtle.

Snippet from example 118540238 in (EntityFacts):

"familialRelationship" : [ {
    "@id" : "https://d-nb.info/gnd/118695940",
    "relationship" : "Vater",
    "preferredName" : "Johann Caspar Goethe"
  }, {
    "@id" : "https://d-nb.info/gnd/118540246",
    "relationship" : "Mutter",
    "preferredName" : "Katharina Elisabeth Goethe"
  }, {
    "@id" : "https://d-nb.info/gnd/11871791X",
    "relationship" : "Schwester",
    "preferredName" : "Cornelia Goethe"
  }, {
    "@id" : "https://d-nb.info/gnd/118795163",
    "relationship" : "Schwager",
    "preferredName" : "Johann Georg Schlosser"
  }, {
    "@id" : "https://d-nb.info/gnd/118628011",
    "relationship" : "Ehefrau",
    "preferredName" : "Christiane von Goethe"
  }, {
    "@id" : "https://d-nb.info/gnd/11854022X",
    "relationship" : "Sohn",
    "preferredName" : "August von Goethe"
  }, {
    "@id" : "https://d-nb.info/gnd/118540254",
    "relationship" : "Schwiegertochter",
    "preferredName" : "Ottilie von Goethe"
  }, {
    "@id" : "https://d-nb.info/gnd/11687256X",
    "relationship" : "Tante",
    "preferredName" : "Johanna Maria Melber"
  } ]

The EntityFacts JSON-LD context document does not contain the property relationship.

I do not think we should follow this approach as it would be the first JSON key that is not mapped to an RDF property.

In the DNB RDF, there are also direct links between person using the agrelon properties in the comment above hasParent,hasSibling, hasSpouse. However, these are not exhaustive and we will need to work with the strings describing the relationship (e.g. "1. Ehefrau", "2. Ehefrau" or "Großonkel" in 118542443 are not covered by agrelon porperties).

Thus, we will have to add a level of indirection to separate relationship and releated person and it should look something like this:

{
   "familialRelationship":[
      {
         "type":"Relationship",
         "label":"Vater",
         "relatedPerson":{
            "id":"https://d-nb.info/gnd/118695940",
            "preferredName":"Johann Caspar Goethe"
         }
      },
      {
         "type":"Relationship",
         "label":"Mutter",
         "relatedPerson":{
            "id":"https://d-nb.info/gnd/118540246",
            "preferredName":"Katharina Elisabeth Goethe"
         }
      }
   ]
}

As the DNB OPAC and the Linked Data Service are currently down, I can not look deeper into how we will get from one to another.

[acka47]

Implementation will not be straightforward as

1. we strive to provide one data structure for people to access and display all familial relationshops
2. the GND RDF provides 3–4 different ways of indicating these (and I missed to make sure in New property and class for qualified relationship statements deutsche-nationalbibliothek/gnd-ontology#5 that there is one way which covers all relationships).

The example from the linked issue illustrates this well:

<https://d-nb.info/gnd/115744126> gndo:familialRelationship <https://d-nb.info/gnd/1018927271>;
  agrelon:hasParent <https://d-nb.info/gnd/1018927271>;
  gndo:hasRelation _:node1ji78aarmx202614979 .

_:node1ji78aarmx202614979 agrelon:hasParent <https://d-nb.info/gnd/1018927271>;
  a gndo:Relationship .

<https://d-nb.info/gnd/115744126> gndo:familialRelationship <https://d-nb.info/gnd/132522136>;
  gndo:hasRelation _:node1ji78aarmx202614980 .

_:node1ji78aarmx202614980 gndo:familialRelationship <https://d-nb.info/gnd/132522136>;
  gndo:functionOrRoleAsLiteral "Halbbruder";
  a gndo:Relationship .

Breaking this down for the hasParent relation between https://d-nb.info/gnd/115744126 and https://d-nb.info/gnd/1018927271:

1. There is one generic familialRelationship statement that does not specify the relationship: <https://d-nb.info/gnd/115744126> gndo:familialRelationship <https://d-nb.info/gnd/1018927271> .
2. There is one direct relationship with agrelon:hasParent: <https://d-nb.info/gnd/115744126> agrelon:hasParent <https://d-nb.info/gnd/1018927271> .
3. There is a relationship as an additional level of indirection, rewritten with a blank node property list it looks like this:

<https://d-nb.info/gnd/115744126> gndo:hasRelation [
  a gndo:Relationship
  agrelon:hasParent <https://d-nb.info/gnd/1018927271> ;
] .

4. Taking a look at the "Halbbruder" relation, we get a fourth way to record a familial relation:

<https://d-nb.info/gnd/115744126> gndo:hasRelation [
  gndo:familialRelationship <https://d-nb.info/gnd/132522136>;
  gndo:functionOrRoleAsLiteral "Halbbruder";
  a gndo:Relationship ] .

Both the reuse of the generic gndo:familialRelationship and the specific agrelon:hasParent in statements about the relationship is problematic as the relationship is not related to the person but two persons are related.

What a shame, I did not notice this earlier. @thoffma, is there any chance to adjust this in the GND RDF? I would imagine something like this for all relations, also the ones where an agrelon property exists:

<https://d-nb.info/gnd/115744126> gndo:hasRelation [
  gndo:relationshipWith <https://d-nb.info/gnd/132522136>;
  rdfs:label "Halbbruder";
  a gndo:Relationship ] .

However, if GND data won't change, we will have to work with how we have and somehow create a uniform relationship data structure out of it, something like I sketched in the previous comment.

[thoffma]

Yes, harmonization would be appropriate here. So that the literal appears in all nodes.

Like this?

<https://d-nb.info/gnd/115744126> gndo:hasRelation [
  a gndo:Relationship;
  agrelon:hasParent <https://d-nb.info/gnd/1018927271> ;
  gndo:functionOrRoleAsLiteral "Vater";
] .

<https://d-nb.info/gnd/115744126> gndo:hasRelation [
  gndo:familialRelationship <https://d-nb.info/gnd/132522136>;
  gndo:functionOrRoleAsLiteral "Halbbruder";
  a gndo:Relationship ] .

Or would it be better to replace also the agrelon vocabulary with the property gndo:familialRelationship inside the bNode?

[acka47]

Or would it be better to replace also the agrelon vocabulary with the property gndo:familialRelationship inside the bNode?

Yes, there should better be only one standard property for linking to the related person. If one needs, one can get the agrelon relationship from the direct links so that it would be redundant.

However, as sketched in my previous comment, I also am a bit uneasy with using gndo:familialRelationship as well as gndo:functionOrRoleAsLiteral on the gndo:Relationship node. This also doesn't fit well with the rdfs:domain defined in the GND Ontology for both properties where gndo:Relationship is not listed:

:familialRelationship
    a rdf:Property, owl:ObjectProperty ;
    rdfs:domain [
        a owl:Class ;
        owl:unionOf (:DifferentiatedPerson
            :Family
        )
    ] .

:functionOrRoleAsLiteral
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:domain [
        a owl:Class ;
        owl:unionOf (:CorporateBody
            :DifferentiatedPerson
            :SubjectHeading
        )
    ] .

So, we are in need of

1. a property that links a gndo:Relationship to the "target" entity of the relation
2. another property (instead of functionOrRoleAsLiteral) for labeling the gndo:Relationship.

As far as I can see, both do not yet exist.

Furthermore, I just noticed that the property gndo:hasRelation does not exist but only
gndo:hasRelationship.

Taken everything into account, it could look something like this (relationshipWith could also be named relatedEntity or similar):

<https://d-nb.info/gnd/115744126> gndo:hasRelationship [
  gndo:relationshipWith <https://d-nb.info/gnd/132522136>;
  rdfs:label "Halbbruder";
  a gndo:Relationship ] .