Note it is a general Liked Data problem that if you put together data from the wild you will wind up with different ways of writing literals as well as URIs that compete with literals.
SPARQL, as it is today, produces the same answers you would get from a relational database if the Unique Name Assumption applies. This is just as true for literals as it is for URIs. Some examples * it is "reasonable" for people to write "8"^^xsd:byte, and otherwise use many different data types when they want to express an integer. * say you are aggregating data into a vocabulary like foaf, once again there are multiple ways that people will encode email addresses no matter what you tell them, for instance as a literal string is reasonable, but also a mailto: URI is reasoanble. One of the missing links in RDF tooling is something to normalize these things. In the wider world, the U.N.A. definitely does not hold, but if you can enforce it in an area, people know how to write SPARQL queries and interpret the results -- otherwise it is a problem for a PhD thesis. On Tue, Sep 8, 2015 at 2:03 PM, Rinke Hoekstra <rinke.hoeks...@vu.nl> wrote: > Hi Kingsley and Dimitris, > > Thanks again for your replies. > > I suggest we leave it for now. I really wasn't asking you to solve my > problem... it's trivial, I can come up with other equally relevant SPARQL > examples if needed. I am well aware of the instability of the DBPedia > property namespace, and only resorted to it because my normal route > appeared to be blocked. > > I apologize if my initial email was overly polemic. > > I was just as surprised as you are that DBPedia behaved differently at > different times: it shouldn't happen. As Kingsley says, the data is > relatively stable. That's the reason I sent the email: just in case there > was some weird bug on your end. I cannot provide proof other than what I > told you. > > For now, a query on: ?city dbpedia-owl:areaCode "020"^^xsd:string seems > to work, so I'm good to go. I'll keep a backup of the DBPedia-property > namespace-based solution just in case the temporal flux appears again. (and > of course, I'll notify you immediately once that happens, with a full > report) > > -Rinke > > > > On Tue, Sep 8, 2015 at 6:12 PM Kingsley Idehen <kide...@openlinksw.com> > wrote: > >> On 9/8/15 11:13 AM, Rinke Hoekstra wrote: >> >> Hi Kingsley, >> >> Thanks for your help. I am aware that the two queries use a different >> predicate; that's part of the problem. >> >> >> You should stick with the predicate that provides the solution you seek. >> > > >> >> >> The issue is that depending on the time at which I try the queries, one >> query will return results, and the other won't (or the other way around). >> >> >> I am trying to find proof of that claim. The data isn't being uploaded >> frequently so I don't see how this kind of temporal flux is possible. As I >> said, stick to the predicate that provides the solution you seek. That >> should produce stable solutions. >> >> Kingsley >> >> >> -Rinke >> >> On Tue, Sep 8, 2015 at 4:58 PM Kingsley Idehen <kide...@openlinksw.com> >> wrote: >> >>> On 9/8/15 8:56 AM, Rinke Hoekstra wrote: >>> >>> Sure, >>> >>> Here's one for the area-codes-as-integers: >>> >>> >>> <http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbp%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fproperty%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbp%3AareaCode+020+.%0D%0A%7D+%0D%0A&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on> >>> http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbp%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fproperty%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbp%3AareaCode+020+.%0D%0A%7D+%0D%0A&format=text%2Fhtml&CXML_redir_for_ >>> subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on >>> >>> >>> That's a SPARQL query based on a query pattern that includes the >>> predicate: <http://dbpedia.org/property/areaCode> >>> <http://dbpedia.org/property/areaCode> >>> <http://dbpedia.org/property/areaCode> . >>> >>> Goto (note: &qtxt as opposed to &query change in URL): >>> >>> >>> http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&qtxt=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbp%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fproperty%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbp%3AareaCode+020+.%0D%0A%7D+%0D%0A&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on >>> <http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbp%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fproperty%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbp%3AareaCode+020+.%0D%0A%7D+%0D%0A&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on> >>> >>> >>> >>> and here's the original query for area-codes-as-strings: >>> >>> >>> <http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbo%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fontology%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbo%3AareaCode+%22020%22%40en+.%0D%0A%7D+%0D%0A&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on> >>> http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbo%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fontology%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbo%3AareaCode+%22020%22%40en+.%0D%0A%7D+%0D%0A&format=text%2Fht >>> ml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on >>> >>> >>> That's based on a SPARQL query pattern that includes the predicate >>> <http://dbpedia.org/ontology/areaCode> >>> <http://dbpedia.org/ontology/areaCode> >>> <http://dbpedia.org/ontology/areaCode> . >>> >>> Goto (note: &qtxt as opposed to &query change in URL): >>> >>> >>> http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&qtxt=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbo%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fontology%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbo%3AareaCode+%22020%22%40en+.%0D%0A%7D+%0D%0A&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on >>> <http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=PREFIX+rdf%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F1999%2F02%2F22-rdf-syntax-ns%23%3E%0D%0APREFIX+rdfs%3A+%3Chttp%3A%2F%2Fwww.w3.org%2F2000%2F01%2Frdf-schema%23%3E%0D%0APREFIX+dbo%3A+%3Chttp%3A%2F%2Fdbpedia.org%2Fontology%2F%3E%0D%0A%0D%0ASELECT+DISTINCT+%3Fx+WHERE+%7B%0D%0A++%3Fx+dbo%3AareaCode+%22020%22%40en+.%0D%0A%7D+%0D%0A&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on> >>> >>> You have two different predicates in your query pattern. Naturally, they >>> would lead to two different solutions. >>> >>> I still don't see the temporal issue in your post i.e., the claim that >>> somehow (within short timeframes) you have a solution that varies. >>> >>> -- >>> Regards, >>> >>> Kingsley Idehen >>> Founder & CEO >>> OpenLink Software >>> Company Web: http://www.openlinksw.com >>> Personal Weblog 1: http://kidehen.blogspot.com >>> Personal Weblog 2: http://www.openlinksw.com/blog/~kidehen >>> Twitter Profile: https://twitter.com/kidehen >>> Google+ Profile: https://plus.google.com/+KingsleyIdehen/about >>> LinkedIn Profile: http://www.linkedin.com/in/kidehen >>> Personal WebID: http://kingsley.idehen.net/dataspace/person/kidehen#this >>> >>> >> >> -- >> Regards, >> >> Kingsley Idehen >> Founder & CEO >> OpenLink Software >> Company Web: http://www.openlinksw.com >> Personal Weblog 1: http://kidehen.blogspot.com >> Personal Weblog 2: http://www.openlinksw.com/blog/~kidehen >> Twitter Profile: https://twitter.com/kidehen >> Google+ Profile: https://plus.google.com/+KingsleyIdehen/about >> LinkedIn Profile: http://www.linkedin.com/in/kidehen >> Personal WebID: http://kingsley.idehen.net/dataspace/person/kidehen#this >> >> > > ------------------------------------------------------------------------------ > > _______________________________________________ > Dbpedia-discussion mailing list > Dbpedia-discussion@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/dbpedia-discussion > > -- Paul Houle *Applying Schemas for Natural Language Processing, Distributed Systems, Classification and Text Mining and Data Lakes* (607) 539 6254 paul.houle on Skype ontolo...@gmail.com :BaseKB -- Query Freebase Data With SPARQL http://basekb.com/gold/ Legal Entity Identifier Lookup https://legalentityidentifier.info/lei/lookup/ <http://legalentityidentifier.info/lei/lookup/> Join our Data Lakes group on LinkedIn https://www.linkedin.com/grp/home?gid=8267275
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