- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Mon, 30 Jan 2006 11:30:42 +0000
- To: Pat Hayes <phayes@ihmc.us>
- CC: tessaris <tessaris@inf.unibz.it>, RDF Data Access Working Group <public-rdf-dawg@w3.org>

v1.625 hopefully fixes this based on Sergio's option 2. (I added an SC operator to that is a solution substition followed by elimination of triple patterns which still had variable in them.) Andy Pat Hayes wrote: >> Pat Hayes wrote: >>>> Moreover, I think that we should adopt a different notation for the >>>> variable substitution in graph templates, since it looks the same as >>>> the one for BGP but it behaves differently. In particular wrt >>>> variables not present in the domain of a pattern solution. >>> >>> There once was a tweak in the definition of substitution mapping which I >>> think handles this, where S(v)=v if v is outside the domain of S, so S >>> maps V to (RDF_T union V). This makes all S's total on templates and >>> maps templates to templates (graphs being the special case of templates >>> with no variables). Would this handle the issue that you are referring >>> to? (If not, I'd like to see an example, because in that case Im not >>> following you.) >> It wont take care of the problem, since by the definition in 10.3.2: >> >> >> """ >> Definition: Graph Template >> >> A graph template is a set of triple patterns. >> >> If T = { t_j | j = 1,2 ... m } is a graph template and S is a solution >> then S(t_j) is a set of one RDF triple if all variables in t_j are in >> the domain of S. S(t_j) is the empty set otherwise. >> >> Write S(T) for the union of S(t_j). >> """ >> >> triples with variables without assignment "disappear"; while mapping the >> variables into themselves would generate an RDF graph with variables. > > Ah, now I see what the problem is that you were referring to. OK. > > Pat > >> --sergio > >

Received on Monday, 30 January 2006 11:31:42 UTC