W3C home > Mailing lists > Public > public-rdf-wg@w3.org > October 2011

Re: proposals for Lists and Seq (ISSUE-77)

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Fri, 21 Oct 2011 12:24:32 +0100
Message-ID: <4EA15670.8090101@epimorphics.com>
To: public-rdf-wg@w3.org


On 21/10/11 12:01, Steve Harris wrote:
> On 2011-10-21, at 11:19, Andy Seaborne wrote:
>>
>> On 20/10/11 14:05, Steve Harris wrote:
>>> On 2011-10-20, at 13:47, Sandro Hawke wrote:
>>>
>>>> On Thu, 2011-10-20 at 13:21 +0200, Dan Brickley wrote:
>>>>> On 20 October 2011 13:13, Steve Harris<steve.harris@garlik.com>   wrote:
>>>>>> I wouldn't be comfortable with marking Seq as "archaic" or similar unless there's a viable alternative, and I don't think List counts.
>>>>>
>>>>> Me neither.  Nor "quaint", "twee", "retro" or "regrettable". It's just
>>>>> what it is, with no great mystery or confusion.
>>>>
>>>> Actually, there's a great deal of confusion.  Please do explain -- in
>>>> one sentence for newbies -- why we have both Seq and List, and with Seq
>>>> better supported in RDF/XML and List better supported in Turtle, and how
>>>> someone should decide which to use.
>>>
>>> Seq has the advantage that it's much easier to query with SPARQL. Still not great, but much easier.
>>>
>>> Finding the 3rd member of a list:
>>>
>>> Seq
>>>
>>> SELECT ?m3
>>> WHERE {
>>>    <x>   rdf:_3 ?m3
>>> }
>>
>> If you assume a notion of well-formedness: else:
>>
>> :x rdf:_1 1 ;
>>    rdf:_1 10 ;
>>    rdf:_1 11 ;
>>    rdf:_2 2 ;
>>    rdf:_9 3 .
>
> I don't see how that's an issue - there isn't a 3rd member in that case, which is a bit at odds with the mathematical definition of a Sequence, but a reasonable thing to want to model.

The text does not say anything about the values: it's just a sequence, 
in a weaker sense than an array having slots at 0, 1, 2, ...

[[
the rdf:Seq class is used conventionally to indicate to a human reader 
that the numerical ordering of the container membership properties of 
the container is intended to be significant.
]]

"numerical ordering"

http://www.w3.org/TR/2004/REC-rdf-schema-20040210/#ch_seq

hence the well-formedness idea.

Others see multiple rdf:_1 as meaningful.

	Andy
Received on Friday, 21 October 2011 11:25:02 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:25:46 GMT