- From: patrick hayes <phayes@ai.uwf.edu>
- Date: Mon, 13 May 2002 10:46:50 -0500
- To: "Danny Ayers" <danny666@virgilio.it>
- Cc: <cmjg@tribble.ilrt.bris.ac.uk>, www-rdf-comments@w3.org
> >[on the text:] >> >>A parser is considered to pass the test if it produces a graph >>isomorphic with the graph described by the N-triples output document. >> >>> > This is wrong, according to the standard definition of graph >>isomorphism >>> > (care when using words without accurate definitions...!). >> >>An RDF graph is a labelled digraph with (some) blank nodes - that is, >>N-Triples "labels" on blank nodes are only artifacts of a graph >>serialisation >>mechanism. I'd always used terms like "isomorphism" to refer to the >>appropriate equivalence relationship for the class of mathematical objects >>I'm talking about at the time. > >I personally wouldn't have a problem with the original wording, but now it's >been mentioned I suppose it has to be tied down. It's not entirely >straightforward - ok, the labels we see might just be artifacts, but does a >bNode carry more meaning than that suggested by the topology? No. > My guess would >be that it does (even if this will be the same for all bNodes), and so >should be considered labelled. Please don't consider bnodes to be labelled. We went through hell getting it clear that they are NOT labelled. If you want to be achingly precise, *define* isomorphism for RDF graphs as follows: there is a bijection (1:1 mapping) from the bnodes of graph A to those of graph B which maps B to A. Then proceed as before. To keep rogue mathematicians at bay, say explicitly that isomorphism of RDF graphs is not graph isomorphism. > > Would the following replacement >>text suffice? >> >>A parser is considered to pass the test if it produces an RDF graph >>(that is, a partially-labelled labelled digraph) isomorphic with the RDF >>graph described by the N-triples output document. > >I'd be tempted to drop 'partially labelled'. I tend to agree on that. Pat
Received on Monday, 13 May 2002 11:46:43 UTC