- From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
- Date: Fri, 16 Nov 2012 12:06:24 +0100
- To: public-rdf-wg@w3.org
If merge is to be understood in same sense as graph-merge (a logical merge), then it is a purely semantic operation. Its definition entirely depends on the semantics of dataset. For instance, if one interprets the graph IRIs as the graph inside the named-graph-pair with this name, then there are pairs of RDF datasets for which the logical merge does not even exist. Further, if we define the merge as a purely syntactical operation, then the operation may also have the meaning of a logical merge in a particular semantics, which in a way would support that the actual semantics of datasets is this particular semantics. For instance, if we define dataset-merge as an operation that graph-merges the graphs in the named-graph-pairs having the same name, then it is equivalent to a logical merge following the kind of semantics that I struggled to defend for a year and a half (while it is incompatible with the logical merge of other semantics). Union and equality have no reason to be defined. Mathematicians have taken care of that ages ago. It would not be wise to define union or equality in ways that differ from the universally recognised notions of equality and union. Isomorphism is an operation that preserves structure, so it can safely be defined independently of the semantics. Tentative definition: """ Two RDF datasets (DG1, NG1) and (DG2, NG2) are dataset-isomorphic iff: - DG1 and DG2 are graph-isomorphic; - For each (n1,g1) in NG1, there exists (n2,g2) in NG2 such that n1=n2 and g1 and g2 are graph-isomorphic; - For each (n2,g2) in NG2, there exists (n1,g1) in NG1 such that n1=n2 and g1 and g2 are graph-isomorphic. """ --AZ Le 14/11/2012 12:34, Andy Seaborne a écrit : > > > On 12/11/12 17:37, Pat Hayes wrote: >> >> On Nov 9, 2012, at 10:12 AM, RDF Working Group Issue Tracker wrote: >> >>> RDF-ISSUE-111 (dataset-operations): Should RDF Concepts define any >>> operations on RDF datasets? [RDF Concepts] >>> >>> http://www.w3.org/2011/rdf-wg/track/issues/111 >>> >>> Raised by: Richard Cyganiak >>> On product: RDF Concepts >>> >>> Such as merge, union, isomorphism, equality, equivalence? >> >> Yes. >> >> Pat > > +1 (but not too prominently - appendix for graph and dataset operations?) > >> >>> >>> Things to keep in mind: >>> >>> * TriG test cases? >>> * Anything that SPARQL needs? >>> >>> >>> >>> >> >> ------------------------------------------------------------ >> IHMC (850)434 8903 or (650)494 3973 >> 40 South Alcaniz St. (850)202 4416 office >> Pensacola (850)202 4440 fax >> FL 32502 (850)291 0667 mobile >> phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes >> >> >> >> >> >> > > -- Antoine Zimmermann ISCOD / LSTI - Institut Henri Fayol École Nationale Supérieure des Mines de Saint-Étienne 158 cours Fauriel 42023 Saint-Étienne Cedex 2 France Tél:+33(0)4 77 42 66 03 Fax:+33(0)4 77 42 66 66 http://zimmer.aprilfoolsreview.com/
Received on Friday, 16 November 2012 11:06:54 UTC