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(Editorial) comments on the SPARQL 1.1 Query Language draft

From: Ivan Herman <ivan@w3.org>
Date: Wed, 25 May 2011 14:04:22 +0200
Cc: Steve Harris <steve.harris@garlik.com>, Andy Seaborne <andy.seaborne@epimorphics.com>
Message-Id: <01ACAF51-091C-4059-AF5B-9A5E4DE91E1D@w3.org>
To: public-rdf-dawg-comments@w3.org
Hi guys,

a few editorial issues. Note that I have _not_ yet read through the algebra (ie, section 18); I may need some more time (and taking a deep breath) before doing that:-)

General comments:
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Sections like #5, #6, #7, etc, very much read like a tutorial (which is good!). Most of these do not make a reference to the algebra, ie, one can really read these sections without problems "linearly". However, the description of, say, GROUP BY uses a formalism that, at this point in reading, is not understandable, unless the reader jumps ahead and reads the formal algebra. The same occurs in section 11.5, 11.6, but also in 12 (e.g., "Subqueries require one additional algebra operator, ToMultiset, which takes lists and returns multistep." or "Becomes ToMultiset(Project(BGP(?x ?y ?z), {?z}))."). Is this really necessary? Can't we stay at that "tutorial" level in those sections? I think this would make the spec much more palatable.

A related issue is the usage of the term 'project' (like "GROUP BY clause cannot be projected") that comes up fairly often but it is not really explained when just reading the document linearly. As an example, I do not really understand what the following clause means in 11.4:

"In a query level which uses aggregates, only expressions consisting of aggregates and constants may be projected, with one exception. When GROUP BY is given with one more more simple expressions consisting of just a variable, those variables may be projected from the level." 

Well, probably I would if I read first the algebra, but I am not yet there…

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do functions/operators like 'bound' 'sameTerm' have a URI now? I saw that, a while ago, the 

http://www.w3.org/ns/sparql#bound

was defined, but the namespace document does not have anything more at the moment. Is the intention to complete that file? 

Also, if there is indeed a URI for these terms, it may be worth noting this fact in the query document itself.

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There are several references to the vcard vocabulary in the examples. There is now a new and widely used version with the vocabulary URI:

http://www.w3.org/2006/vcard/ns#	

I think it would be good to use that in the examples 

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Specific editorial buglets:

1.2.4: 'following' -> 'following'

11.5 second paragraph 'infact' -> 'in fact'

11.5 last paragraph, 'unless the ; separator is used this requires' -> 'unless the ; separator is used, this requires'

17.4.2.1 there seems to be an extra \t for isURI in its definition

Thanks!

Ivan

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Ivan Herman, W3C Semantic Web Activity Lead
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Received on Wednesday, 25 May 2011 12:02:19 GMT

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