"ObjectProperty" and "DatatypeProperty"

 While most of the spec. has been tightened up nicely, I'm afraid the names of  the two main OWL Property classes are still terribly confusing, and may  obscure a significant ambiguity.  First off, a natural English speaker's intuition is that something named  "ObjectProperty" would be the class of Properties of Objects, i.e., whose  _domain_ was (a subset of) Object. This is doubly confusing, because in the  RDF spec "object" is defined as the _value_ of a predicate/Property. In fact,  this is actually triply confusing, because in RDF "object" refers to the  value of _any_ Property, specifically including literal values. As if to  admit this problem, the AS&S actually uses "individualvaluedPropertyID" as  the name of the corresponding abstract syntax element. This name is much  better, but unfortunately it is not clear to me that it is entirely accurate  either (see below).  Perhaps even more pernicious is the name "DatatypeProperty", which is used to  refer not even to Properties whose values are rdfs:Datatype's, but rather to  Properties whose values are rdfs:Literal's. The name used in the AS&S  ("datavaluedPropertyID") for the corresponding abstract syntax element is  only barely tolerable; obviously the much more transparent names would be  LiteralValuedProperty and literalValuedPropertyID.  Lost in all this is an apparent ambiguity in the spec. Despite having no  formal definition of the term "object", section 5.2 of the AS&S  (http://www.w3.org/TR/owl-semantics/rdfs.html#5.2) asserts (in the second  table, "Characteristics of OWL classes, datatypes, and properties") that  "Class instances are all OWL objects."  However, section 5.4  (http://www.w3.org/TR/owl-semantics/rdfs.html#5.4) insists that IOT and IOC  must be disjoint. Thus, clearly "OWL objects" must refer to the union of IOT  and IOC, right? Only, returning to 5.2, interpretations of owl:ObjectProperty  asserted to be contained in IOTxIOT. Well, which is it? Are Classes Objects,  i.e., is IOC a subset of IOT, or not?  And if not, then what type of Property are rdf:type, rdfs:range, rdfs:domain,  etc. in the OWL universe? --  Kevin D. Keck http://vimss.lbl.gov/~kdkeck/ 510-486-4856

Received on Monday, 7 July 2003 16:20:49 UTC