- From: Dan Connolly <connolly@w3.org>
- Date: 30 Oct 2002 17:15:16 -0600
- To: Pat Hayes <phayes@ai.uwf.edu>
- Cc: Brian McBride <bwm@hplb.hpl.hp.com>, w3c-rdfcore-wg@w3.org
On Wed, 2002-10-30 at 16:37, pat hayes wrote: [...] > Then Dave can just delete "identified by". Nodes *are* urirefs yes, please. Some details: > -------- > > 0.2 Graph syntax > > ..... > To describe RDF graphs it is first necessary to define the things > that can act as nodes and arcs of the graph. There are three kinds of > node in an RDF graph: urirefs, blank nodes and literals. A uriref is > defined to be a URI reference in the sense of [RFC 2396]. Blank to be an +absolute+ URI reference in the sense of... > (unlabeled) nodes are considered to be drawn from some set of > 'anonymous' syntactic entities which have no label and are unique to > the graph. Two graphs which differ only by having different blank > nodes are isomorphic; I think I know what you mean there, but it doesn't seem very precise. Hmm... > we will not bother to distinguish between > isomorphic graphs. Literals come in several forms. Simple literals > consist of a unicode character string plus an optional XML language > tag; Please, no. Just like urirefs *are* labels, strings *are* literals, please. That is: Simple literas are either unicode character strings or unicode character strings paired with a language tag. (language tags aren't novel to XML; they're an Internet-wide thing.) > typed literals consist of a unicode character string paired with > a uriref which indicates a datatype; and a special class of XML typed > literals is distinguished which can also have an XML lang tag. > Finally, every arc in an RDF graph is labelled with a uriref. The > same uriref may label several arcs and also be a node in the graph. > An RDF graph can then be formally defined as a set of triples of the > form <S, P, O>, where P is a uriref, S is either a uriref or a blank > node, and O is either a uriref, a blank node, or a literal. [... very nicely put...] -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 30 October 2002 18:16:00 UTC