7 Replies Latest reply: Feb 12, 2013 8:09 AM by 24743 RSS

    delete blank nodes

    24743
      Hi

      I once (in 2007) asked if it could possible to asure that with these triples

      <URI> person _:bn1
      _:bn1 name xxx
      _:bn1 email yyy

      it should not be possible to delete the first triple without first deleting the other two (a kind of referential constraint).

      Your answer: "Thanks! That is a good example. We will take it as feedback for future releases."

      So will this be implemented in the next version?

      Regards - Christian
        • 1. Re: delete blank nodes
          alwu-Oracle
          Hi Christian,

          Just to clarify, what does your application (or what do you) expect when someone inserts a triple as follows? Assume _:bn1 is a fresh bnode.

          <URI> :fatherOf _:bn1

          Thanks,

          Zhe
          • 2. Re: delete blank nodes
            24743
            Hi Zhe

            That it can be used as <o> in f.ex:

            sem_match ('{?s :fatherOf ?o . ?o :hasName ?child_name . ?o :hasEmail ?child_email}'

            Thanks - Christian
            • 3. Re: delete blank nodes
              alwu-Oracle
              Thanks Christian. A further clarification.

              Does your application model allow the following?
              <URI> person _:bn1
              <URI2> person _:bn1
              _:bn1 name xxx
              _:bn1 email yyy

              If so, should it be possible to delete the first assertion by itself?

              Thanks,

              Zhe Wu
              • 4. Re: delete blank nodes
                24743
                Hi Zhe

                With the same email, I see no reason why <URI> and <URI2> should not be allowed in the same model.

                About deletion - then it should at least not be allowed to delete all triples with _:bn1 as object since the name and email triples would then be of no value.

                Regards - Christian
                • 5. Re: delete blank nodes
                  24743
                  Hi Zhe

                  Could also be a result like

                  <URI> :hasResult _:bn1
                  _:bn1 :hasValue xxx
                  _:bn1 :hasUnit yyy

                  where you would loose all context if the first triple was deleted.

                  ps: with the "open world assumption" of the semantic web why isn't "optional" the default in SPARQL?

                  Regards Christian
                  • 6. Re: delete blank nodes
                    alwu-Oracle
                    Hi Christian,

                    I only vaguely understand the "context" you mentioned.

                    For example,

                    <http://my.com/friendOf> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#ObjectProperty> .
                    _:jA0 <http://my.com/friendOf> _:jA1 .

                    Do you think the second triple is out of "context?" It actually encodes something meaningful.

                    Thanks,

                    Zhe
                    • 7. Re: delete blank nodes
                      24743
                      Hi Zhe

                      By "context" I mean that if you have a result (value and unit) as above and delete the "<URI> :hasResult _:bn1" triple you don't know what the result is for. In worst case you might have to do the experiment/measurement again.

                      Regards - Christian