Ontop Protégé blank nodes syntax

[JBPressac]

Hello,
What is the syntax for blank nodes in Protégé Maping Manager ? I would like to use the BIO ontology to declare the date of birth of someone and tried the following:

:person{id} a :Person ; foaf:name {nom_usuel_forme_orthographique_1}^^xsd:string; bio:birth :_birth. 
_:birth a bio:Birth; bio:date {annee_naissance}.

But I have an error: No match found.

I also tried the following without success:

:person{id} a :Person ; foaf:name {nom_usuel_forme_orthographique_1}^^xsd:string; bio:birth [a bio:Birth; bio:date {annee_naissance}].

Thanks,

[ghxiao]

Hi,

Blank node works similarly as for IRIs, the difference is that you need to use _: as prefix. You can construct a BNODE with syntax :{column1}{column2}.

Note that you have to supply a label to BNode, unlabelled BNode [] is not supported by Ontop.

You also need to be careful about the semantics of BNode. It works very similarly to IRI, so you do want your columns to identify the BNode with a RDF Graph. The difference with IRI is that such identifiers are internal to the Graph. When you query the graph, the identifiers are not preserved.

In your example, as far as I understood, id is enough for identify a birth. So you can write a mapping like:

:person{id} a :Person ; bio:birth _:birth_{id} . 
_:birth_{id} a bio:Birth; bio:date {annee_naissance}.