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Re: Closing ISSUE-13

From: Ivan Herman <ivan@w3.org>
Date: Thu, 10 May 2012 15:20:38 +0200
Cc: Arnaud Le Hors <lehors@us.ibm.com>, David Wood <david@3roundstones.com>, public-rdf-wg Group WG <public-rdf-wg@w3.org>
Message-Id: <9A69C3A2-C9FF-41FB-AAB0-0E3D3ADA5899@w3.org>
To: Richard Cyganiak <richard@cyganiak.de>
Ah. I think I found out why this would indeed work: namely because 

- DocumentFragment is a subclass of Node[1]
- equality is defined on nodes, and indeed looks at the node names (that is what I was afraid of) but, looking at the table in [1], the name of a Document Fragment is always fixed (and is set to '#document-fragment'). Ie, the equality will work because, in fact, the DOM3 spec is such that it has a reserved 'name' for document fragments (and that is what I was looking for).

So you are right, it works, thanks to those clever DOM3 editors:-). Is it worth putting a note into the document to make this clear? Or is it so obvious that this discussion is just the outcome of my own stupidity?

Ivan

[1] http://www.w3.org/TR/DOM-Level-3-Core/core.html#ID-1950641247



On May 10, 2012, at 15:06 , Richard Cyganiak wrote:

> Ivan,
> 
> On 10 May 2012, at 14:04, Ivan Herman wrote:
>> - A.isEqualNode(B)[1] compares the notes A and B _and_ its children. Ie, it compares, among other things, the nodeName of the two document fragments
> 
> Sure, but:
> 
>> - the LV mapping returns the result of the following transforms on L (lexical value)
>> wrap L into _something_ -> xmldoc -> domdoc -> domfrag -> normalize()  
> 
> No.
> 
> [[
> Let domfrag be a DOM DocumentFragment whose childNodes attribute is equal to the childNodes attribute of domdoc's documentElement attribute
> ]]
> 
> domfrag is a *new* document fragment that includes only the *child nodes* of domdoc's document element. It does *not* include the document element.
> 
>> So I can be evil enough and wrap a lexical value into a _different_ XML element before doing the rest of the transformation for each lexical value.
> 
> You can do that and there is nothing evil about it.
> 
>> As a result, the values will always be different under the value space comparison.
> 
> No. This gives you different domdocs, but equivalent domfrags. After normalization, they will compare equal.
> 
>> It is obviously a stupid and pathological case, but the exact wording of the algorithm does not exclude that...
> 
> I think you are mistaken.
> 
> Best,
> Richard
> 
> 
>> 
>> Ivan
>> 
>> 
>> [1] http://www.w3.org/TR/DOM-Level-3-Core/core.html#Node3-isEqualNode
>> 
>> On May 10, 2012, at 14:27 , Richard Cyganiak wrote:
>> 
>>> Ivan,
>>> 
>>> On 10 May 2012, at 09:11, Ivan Herman wrote:
>>>> (First of all, I explicitly cc this to Arnaud; he was one of the co-editors of the DOM3 spec, it would be good if he could review that to be on the safe side...)
>>> 
>>> +1!
>>> 
>>>> the only thing I am uncertain about is that issue about the arbitrary XML tag enclosing the whole thing. We clearly need that, but how does that exactly affect the algorithm?
>>> 
>>> The thing with the arbitrary enclosing start and end tag was taken straight from RDF 2004. It's in the definition of the lexical space.
>>> 
>>>> After all, A.isEqualNode(B) compares the nodes' names; if different arbitrary enclosing terms are used, then this will return False, although our intention is to say True...
>>> 
>>> But A.isEqualNode(B) compares the *values*, and the values are the result of applying the L2V mapping, and the L2V mapping returns only the *child nodes* of the document element. So the arbitrary element that we created is *not* being compared; only the list of its children is compared.
>>> 
>>>> Somehow the lexical-to-value mapping algorithm has to keep track, when creating xmldoc, whether such a wrapper element has been added to the original literal or not.
>>> 
>>> I'm not sure what you mean. If the original literal already is properly wrapped in matching start and end tags (that is, it's already a well-formed XML document, not just an XML fragment), then the phrasing as is just wraps it into another element. Everything should still work.
>>>> 
>>>> I am not sure what the best way of handling that is. Maybe, conceptually, that top level wrapping element is a predefined RDF element, and must be used only when there is no wrapping element in the original lexical form in the first place.
>>> 
>>> I'm not sure what problem this would solve.
>>> 
>>>> (In any case, this is not something the author of the RDF content should see.)
>>> 
>>> They don't.
>>> 
>>> Best,
>>> Richard
>>> 
>>> 
>>> 
>>>> 
>>>> Ivan 
>>>> 
>>>> 
>>>> 
>>>> On May 9, 2012, at 20:12 , Richard Cyganiak wrote:
>>>> 
>>>>> Dave, all,
>>>>> 
>>>>> I have updated the RDF Concepts ED according to today's resolution. Please review.
>>>>> 
>>>>> http://dvcs.w3.org/hg/rdf/raw-file/default/rdf-concepts/index.html#section-XMLLiteral
>>>>> 
>>>>> RDF Semantics still needs to be updated accordingly (make rdf:XMLLiteral optional and interpret it only under D-Entailment, like any other datatype).
>>>>> 
>>>>> I've taken the liberty to create an action (on a randomly chosen RDF Semantics editor):
>>>>> 
>>>>> https://www.w3.org/2011/rdf-wg/track/actions/170
>>>>> 
>>>>> No objection to the status change.
>>>>> 
>>>>> Best,
>>>>> Richard
>>>>> 
>>>>> 
>>>>> 
>>>>> On 9 May 2012, at 17:45, David Wood wrote:
>>>>> 
>>>>>> Hi all,
>>>>>> 
>>>>>> Today, we resolved [1]:
>>>>>> [[
>>>>>> RESOLVED: in RDF 1.1: [a] XMLLiterals are optional; [b] lexical space consists of well-formed XML fragments; [c] the canonical lexical form is http://www.w3.org/TR/xml-exc-c14n/, as defined in RDF 2004; [d] the value space consists of (normalized) DOM trees.
>>>>>> ]]
>>>>>> 
>>>>>> Richard's proposal [2], that evolved into this resolution, was meant to close ISSUE-13 [3].  So, I have changed the status of ISSUE-13 to "pending approval" and suggest that the implementation of this resolution be considered editorial in nature.
>>>>>> 
>>>>>> Any objections?
>>>>>> 
>>>>>> Regards,
>>>>>> Dave
>>>>>> 
>>>>>> [1] http://www.w3.org/2011/rdf-wg/meeting/2012-05-09#resolution_1
>>>>>> [2] http://lists.w3.org/Archives/Public/public-rdf-wg/2012May/0006.html
>>>>>> [3] https://www.w3.org/2011/rdf-wg/track/issues/13
>>>>>> 
>>>>>> 
>>>>>> 
>>>>> 
>>>>> 
>>>> 
>>>> 
>>>> ----
>>>> Ivan Herman, W3C Semantic Web Activity Lead
>>>> Home: http://www.w3.org/People/Ivan/
>>>> mobile: +31-641044153
>>>> FOAF: http://www.ivan-herman.net/foaf.rdf
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>> 
>>> 
>> 
>> 
>> ----
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>> 
>> 
>> 
>> 
>> 
>> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Thursday, 10 May 2012 13:17:51 GMT

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