pfps-12 lists are not well formed from Peter F. Patel-Schneider on 2003-06-18 (www-rdf-comments@w3.org from April to June 2003) (original) (raw)

This appears to be on the right track, but I have no way of viewing the other changes, and no way of viewing the changes in context, so I don't see how I can determine whether the changes are satisfactory.

Peter F. Patel-Schneider Bell Labs Research Lucent Technologies

From: Dan Brickley <danbri@w3.org> Subject: Re: pfps-12 lists are not well formed Date: Wed, 18 Jun 2003 12:28:27 -0400

resent copying Karsten, who also raised this issue. Karsten, could you respond per the request below, letting us know if this is a satisfactory resolution of your concern?

Thanks again for your comments on our work,

Dan

previous discussion: http://lists.w3.org/Archives/Public/www-rdf-comments/2003JanMar/0422.html

• Dan Brickley <danbri@w3.org> [2003-06-18 12:16-0400]

  • Peter F. Patel-Schneider <pfps@research.bell-labs.com> [2003-05-25 07:24-0400]

    From: Brian McBride <bwm@hplb.hpl.hp.com> Subject: pfps-12 lists are not well formed Date: Sat, 24 May 2003 13:58:39 +0100

    Peter,

    Danbri and I have been discussing how to resolve your issue about the wellformedness of lists:

    http://www.w3.org/2001/sw/RDFCore/20030123-issues/#pfps-12

    We are proposing to add the following note to the text at:

    http://www.w3.org/TR/rdf-schema/#ch_collectionvocab

    as the last paragraph.

    [[ NOTE: It is possible to construct RDF graphs that use the RDF collections vocabulary to partially describe a list. Similarly there are graphs that use this vocabulary in a way that is consistent with the RDF(S) formal semantics, yet do not represent "well formed" lists. ]]

    We considered trying to trying to provide a full prose account of the wellformedness of lists, but are currently disinclined to attempt such an intricate task in natural language.

    Will adding this note address your concern. If not, could you please suggest alternative text that you would find more satisfactory.

    Brian

    I fail to see how this response addresses my comment.

    I don't see how it addresses

    The RDF Schema document provides intended meanings for some of the RDFS vocabulary that is not supported by the RDF Semantics. Vocabulary that fits into this category includes rdfs:label and rdfs:comment. [from http://lists.w3.org/Archives/Public/www-rdf-comments/2003JanMar/0126.html]

    I don't see how it addresses

    Consider the following three examples (slightly reformatted but otherwise unchanged):

    rdf:type is an instance of rdf:Property that is used to state that
    a resource is an instance of a class.  A triple of the form:
        R rdf:type C
    states that C is an instance of rdfs:Class and R is an instance of C.
    
    rdf:first is an instance of rdf:Property that is used to indicate
    the first item of a list.  A triple of the form:
        L rdf:first O
    states that L is an instance of rdf:List and that O is the first
    item of the list. 
    
    rdfs:label is an instance of rdf:Property that is used to provide a
    human-readable version of a resource's name.  A triple of the form:
        R rdfs:label L
    states that L is a human readable label for R.

    There is essentially no difference between the way these three are worded. However, the first (rdf:type) is a fundamental part of the semantics of RDF. There are semantic conditions in RDF that make the description above for rdf:type part of the very meaning of RDF. The second (rdf:first) and third (rdfs:label), on the other hand, have a very different status. There are no semantic conditions that force the descriptions above for these two vocabulary elements to play the roles given for them. [from http://lists.w3.org/Archives/Public/www-rdf-comments/2003JanMar/0133.html]

    The point of my comments here has always been that there are parts of the RDF Schema document that go beyond what is supported by the RDF semantics. I believe that these parts of the document should be changed, and that changes to other parts of the document will not suffice to override these over-reaching parts of the document.

    For the case of rdf:first above, I would much prefer

     rdf:first is an instance of rdf:Property that can be used to build
     descriptions of lists and other list-like structures.  A triple of
     the form:
         L rdf:first O
     states that there is a first-element relationship between L and O.
    
    Note:  RDFS does not require that there be only one first element
    of a list-like structure, or even that a list-like structure have a
    first element.

  This looks good. At the June 6th telecon[1] we decided to run with your proposed form of words, but note that your text didn't mention the domain and range constraints associated with these concepts.

  A slightly amended form is: [[ rdf:first is an instance of rdf:Property that can be used to build descriptions of lists and other list-like structures. A triple of the form:

  L rdf:first O

  states that there is a first-element relationship between L and O. The rdfs:domain of rdf:first is rdf:List. The rdfs:range of rdf:first is rdfs:Resource.

  Note: RDFS does not require that there be only one first element of a list-like structure, or even that a list-like structure have a first element. ]]

  I note that similar changes would have to be make for at least rdf:rest and rdf:List.

  Agreed.

  The WG (per [1]) proposes to close this issue by resolving to adopt text in the above form for the RDF lists vocabulary.

  Please reply to this message as to whether this response is satisfactory, copying www-rdf-comments@w3.org.

  Dan

  [1] http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003Jun/0067.html

Received on Wednesday, 18 June 2003 16:06:58 UTC