unionOf vs. disjointUnionOf in the RDF mapping

Hi!

The reverse RDF mapping contains the following entry for 'unionOf' in table 6 ("Descriptions"):

  Pattern:
  --------
    _:x rdf:type owl:Class
    _:x owl:unionOf T(SEQ y1 ... yn)

  Description:
  ------------
    ObjectUnionOf( DESC(y1) ... DESC(yn) )

Analogue for 'owl:intersectionOf', 'owl:complementOf', and 'owl:oneOf'.

On the other hand, table 7 ("Axioms") defines the mapping for 'disjointUnionOf' as:

  Pattern:
  --------
    x owl11:disjointUnionOf T(SEQ y1 ... yn) 	 

  Axiom:
  ------
    DisjointUnion( DESC(x) DESC(y1) ... DESC(yn) )

I have several questions:

* Why is 'unionOf' in the "descriptions" table and 'disjointUnionOf' in the "axioms" table?

* Why is there an additional typing triple "_:x rdf:type owl:Class" for 'unionOf', but not for 'disjointUnionOf'?

* Why is there a bNode on the left hand side of 'unionOf' (there's none for 'disjointUnionOf')? AFAICS, this notation makes the RDF graph

  G := {
    ex:C rdf:type owl:Class .
    ex:D1 rdf:type owl:Class .
    ex:D2 rdf:type owl:Class . 
    ex:C owl:unionOf ( ex:D1 ex:D2 ) .
  }

unmappable to Functional Syntax, or at least the unionOf triple doesn't get mapped. Note that G is a valid OWL-1.0-DL ontology, so this would break backwards compatibility.

* Why is the Functional-Syntax expression for 'unionOf' called "ObjectUnionOf"? I mean, why the "Object"? (There is no "Object" for 'disjointUnionOf' expressions.)


Michael

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
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