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7 Replies Latest reply: Feb 12, 2013 6:09 AM by 24743 RSS

delete blank nodes

24743 Newbie
Currently Being Moderated
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 Pro
    Currently Being Moderated
    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 Newbie
    Currently Being Moderated
    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 Pro
    Currently Being Moderated
    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 Newbie
    Currently Being Moderated
    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 Newbie
    Currently Being Moderated
    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 Pro
    Currently Being Moderated
    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 Newbie
    Currently Being Moderated
    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

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