- From: Brian McBride <bwm@hplb.hpl.hp.com>
- Date: Fri, 14 Feb 2003 20:57:36 +0000
- To: Frank Manola <fmanola@mitre.org>, w3c-rdfcore-wg@w3.org
Well held that Man! (English for "good catch") The comment below on the vocab doc doesn't just apply to the reification section, there are many such instances, e.g.: [[The triple P rdfs:range C states that P is an instance of the class rdf:Property, that C is an instance of the class rdfs:Class and that the resources denoted by the objects of triples whose predicate is P are instances of the class C.] That one should go to comments. Brian At 12:02 14/02/2003 -0500, Frank Manola wrote: >Following up on item 9 in today's agenda, here are some potential problem >areas in Concepts and Vocabulary (I don't claim these are exhaustive): > >Concepts Section 3.1 begins: > >"The underlying structure of any expression in RDF can be viewed as a >directed labelled graph, which consists of nodes and labelled directed >arcs that link pairs of nodes (these notions are defined more formally in >section 6). The RDF graph is a set of *triples*: > >[image of the RDF triple comprising (subject, predicate, object)] > >Each property arc represents a *statement* of a relationship between the >things denoted by the nodes that it links, having three parts: > > 1. a property that describes some relationship (also called a predicate), > 2. a value that is the subject of the *statement*, and > 3. a value that is the object of the *statement*. > >The direction of the arc is significant: it always points toward the >object of a *statement*. > >The meaning of an RDF graph is the conjunction (i.e. logical AND) of all >the *statements* that it contains." > >I've highlighted *triple* and *statement* in the above. The text seems >mostly to be talking about the subject/predicate/object of *statements*, >except for the introduction, which seems to suggest it's talking about >*triples*. A question is whether we're going to use subject, predicate, >and object for talking both about components of triples, and components of >statements and, if so, how we keep them straight. Note that the abstract >syntax uses these terms to refer to parts of *triples*. > >Also, in bullets 2 and 3, tht term "value" is a bit ambiguous: it could >be read either as referring to a URIref, or to the thing denoted by that >URIref. Given the wording in the preceding phrase, changing "a value" to >"the thing" would clarify that it was talking about the thing denoted, >rather than the URIref (if that's what it is talking about). > >Concepts Section 3.4, the third sentence, says: > >"A literal may be the object of an RDF *statement*, but not the subject or >the arc" > >This seems to mix several things. A literal sounds like the lexical >thing, which would be a reasonable object of a triple, but less-clear for >a statement (presumably it's the value denoted by the literal that would >be the object of a statement). "Arc" seems to be mixing in the drawing >terminology from Section 3.1, and it's not clear it belongs here. > >Concepts Section 3.5 starts: > >"Some simple facts indicate a relationship between two objects. Such a >fact may be represented as an RDF triple in which the predicate names the >relationship, and the subject and object denote the two objects." > >In this section, the term "fact" is used as the thing represented as an >RDF triple. In Section 3.1 the thing represented as a triple seemed to be >a "statement". There may or may not be a problem using "fact" in this >kind of text, but its relationship to "statement" needs to be made >clear. Also, "object" is used in two different ways, as the things >denoted by subjects and objects, and as the third component of a triple. > >Vocabulary Section 5.3.1: > >This section starts with some nice text that is clearly about subjects, >predicates, and objects of *statements*. > >Section 5.3.2 (rdf:subject) then says: > >"A *triple* of the form: > >S rdf:subject R > >states that S is an instance of rdf:Statement and that the subject of S is R" > >This may or may not be problematic. The question is whether the reader >will interpret S and R as the URIrefs involved in the corresponding >triple, or as the resources denoted by S and R. Similar comments apply to >sections 5.3.3 and 5.3.4. > >--Frank > > > >-- >Frank Manola The MITRE Corporation >202 Burlington Road, MS A345 Bedford, MA 01730-1420 >mailto:fmanola@mitre.org voice: 781-271-8147 FAX: 781-271-875
Received on Friday, 14 February 2003 15:56:26 UTC