Comments about blank nodes in Editors' draft of SPARQL update

1/ "Blank node labels in QuadDatas are assumed to be disjoint from the
blank nodes in the Graph Store and will be inserted as new blank nodes. "
  Well, in some sense, the label is going to be disjoint from any blank
  node, as these are two different sorts of things.  I suggest using the
  RDF graph merge operation instead of insert.

2/ "Since blank node labels are only unique within each specific
context, blank nodes in the QuadData will not match existing data either
in DELETE DATA requests. The DELETE/INSERT and DELETE operations can be 
used to remove triples containing blank nodes. "
  Blank node labels are not "unique within each specific context".
  The only "matching" operation available is RDF graph matching, in
  which different blank nodes can certainly match.

3/ "Blank nodes are therefore prohibited in a delete template. It should
be noted that this restriction is not in the grammar for DELETE. "
  It seems to me to be very bad form to hide this condition in the "fine
  print".  It would be much better to allow them, but make them
  harmless, or, even better, make them *useful*.

4/ I think that it would be much better to define updates more in terms
of existing machinery (merging, instance, etc.), instead of using all
this new machinery.  A better, more useful, better specified
specification is likely to result.Comments about blank nodes in Editors'
draft of SPARQL update


Peter F. Patel-Schneider
Bell Labs Research

Received on Wednesday, 20 April 2011 20:14:27 UTC