- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Wed, 25 Jan 2006 15:06:28 +0000
- To: "Patrick J. Hayes" <phayes@ihmc.us>
- CC: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Patrick J. Hayes wrote: > Reading through, some miscellaneous > comments/questions/suggestions(?). > ------ > 2.1.4 > "Triple Patterns are grouped together with {}(braces)." > Possibly mention here that these groupings determine scope > of bnode identifiers(?) <<Do they, in fact? That is, > should we read > {{_:a :p :q .} > {_:a :r :b .}} > as having two bnodes in it, or one? Im presuming two, as > otherwise what are the {} boundaries for? >> It's two BGPs. {} really delimit groups. I'm going to add that a (filtered)BGP is a sequence of triple patterns or filters. Which answers the question of what { BGP1 optional { BGP2 } BPG3 } really means. > > 2.1.5 Examples of Query Syntax > > The reader is tempted to ask, what about mixing the > variable prefixes in a single query, such as > > PREFIX dc: <http://purl.org/dc/elements/1.1/> PREFIX : > <http://example.org/book/> SELECT $title WHERE { :book1 > dc:title ?title } > > Is that legal? If so, suggest fix one of the examples to > show this. Good idea - done. > > BTW, some of the example answer tables have the variable > name with ? included, others not: suggest they should be > consistent for clarity. I found one. If you find any more, please let me know. I believe there is a daemon that goes round putting them back in when I'm not looking. > > 2.1.7 > The bindings shown are to quoted strings which aren't > typical. Might be better to show a binding to a URI(?) > I've changed the y binding to <http://example/a> > 2.2 > > "This definition of RDF Term collects together several > basic notions from the RDF data model." > // > "......the RDF data model, but updated to refer to IRIs > rather than URIs." Done. but s/URIs/RDF URI references/ Good link. > (Could refer to > http://www.w3.org/TR/rdf-concepts/#section-Graph-URIref > "Note: this section anticipates an RFC on > Internationalized Resource Identifiers. Implementations > may issue warnings concerning the use of RDF URI > References that do not conform with [IRI draft] or its > successors.".) > > "Note that all IRIs are absolute; they may or may not > include a fragment identifier [RFC3987, section 3.1]. Also > note that IRIs include URIs [RFC3986] and URLs." > ? Should perhaps say here that they include URI references > (?) I believe that 3986 cleared up use of URI reference to be the case of not absolute and that #frags are part of absolute URIs. > > Definition: > "A query variable is a member of the set V where V is > infinite and disjoint from RDF-T." > Why infinite? We only need enough for a single query. It was a comment. I think that the defn being here does not carry teh connection to just one query. > > "The following triple pattern has a subject variable > (the variable book), a predicate of dc:title and an object > variable (the variable title)." > predicate of//predicate Done > > Triple pattern: Why not allow bnodes in property position > as well, with the same disclaimers about not matching any > current RDF graph? There isn't any good semantic reason to > forbid that case either. (If this would require a WG > decision, forget it :-) The syntax allows it. Defn fixed. Definition: Triple Pattern A triple pattern is member of the set: (RDF-T union V) x (I union RDF-B union V) x (RDF-T union V) (Could even add literals for complete symmetry. Not done as literals in the predicate would be rather confusing for no value.) > > --------- > > I started commenting on section 2.4 and 2.5 but its easier > to redraft them. (The current definition of 'pattern > solution" is wrong and can't be fixed until the scoping > graph is mentioned, which requires re-ordering some > material). > For my best attempt so far, see > http://www.ihmc.us/users/phayes/Section2.4revized.html (I > cut out some of your html and edited it. <<comments like > this>> ) > > Im rather confused, I confess, by the various distinctions > (pattern solution, query solution,...) in section 2.4, so > that section is still a muddle. I think some of it ls left > over from earlier versions. For example, Pattern Solution > refers to "RDF terms occurring in G" which is wrong. In > fact, I don't think there is any way to distinguish > between variable substitution and pattern solution at this > point, since the latter can't be defined properly until > the scoping set has been mentioned. > > ------- > > Sorry, I only got back to this tonight, so it likely needs > more work but I'll send this now to get it to you before > the telecon. > > Pat > > More to follow. Andy
Received on Wednesday, 25 January 2006 15:06:44 UTC