W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > January to March 2007

Re: rq25 review comments

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Tue, 20 Feb 2007 15:32:40 +0000
Message-ID: <45DB1498.9020908@hp.com>
To: SOURIPRIYA.DAS@ORACLE.COM
CC: public-rdf-dawg@w3.org

(text version - not everyone can easily work with doc files)

SOURIPRIYA.DAS@ORACLE.COM wrote:
> I have attached a few review comments on rq25. Thanks. -- Souri.

I looked at the syntax of GroupGraphPattern (<Ggp>, for short) and its use in 
the examples in the “Revision 1.13” (Date 2007/02/16, 18:06:24 hrs) version of 
“SPARQL Query Language for RDF” document. Here are my comments:

Summary:
•	Based on the current grammar, <Ggp> probably can be expressed as a regular 
expression:

<Ggp> := `{` <Bgp>? (<NonTriplesgp> ‘.’? <Bgp>?)* ‘}’

or equivalently (using some self-explanatory notations and with grammar rule 
[32] for GroupOrUniongp broken up for using Ggp and UNIONgp)

<Ggp> := `{` <Bgp>?
             (
               (<constraint> | <OPTIONALgp> | <UNIONgp> | <GRAPHgp> | <Ggp>)
               ‘.’?
               <Bgp>?
             )*
          ‘}’
•	Separator vs. Terminator: Based on the current grammar, rules for use (or 
non-use) of ‘.’ are the following:

o	[R1] Mandatory use as a separator between triples in a <Bgp>
o	[R2] Must not be used as a terminator for the last triple in a <Bgp> (or as 
a separator between the last triple of a <Bgp> and an immediately following 
<NonTriplesgp>).
o	[R3] Optional use as a terminator for <NonTriplesgp>.
•	One way to fix the instances of illegal use (enumerated below) probably 
would be to allow use of ‘.’ optionally as a terminator for (the last triple 
of) a <Bgp>.
o	I am okay with that workaround. However, for simplicity, my preferred 
solution would be to require use of ‘.’ as a (mandatory) terminator for each 
triple (thus requiring a ‘.’ at the end of each <Bgp> as well unlike the R1 
rule above used currently) and maybe also for each <NonTriplesgp> (thus 
requiring, unlike the optional nature of rule R3 above, a ‘.’ at the end of 
each <constraint>, <OPTIONALgp>, etc.).

Instances of illegal use of ‘.’ in GroupGraphPatterns used in examples [NOTE: 
All of these instances are violations of rule R2 above]:
•	The example in Sec 2.1 (on page 7) uses ‘.’ as a terminator.
•	The example in Sec 3.2 (on page 11) uses ‘.’ as a separator between a triple 
and a non-triple (FILTER, in this case).
•	The example in Sec 3.2 (on page 11) uses ‘.’ as a terminator (for the last 
triple).
•	Both the examples in Sec 5.2 (on page 18) use ‘.’ as terminator (for the 
respective last triples).
•	The three examples in Sec 5.4 (on page 19) use ‘.’ as terminator and/or as 
separator between a triple and an immediately following non-triple.
•	Same problem with the examples in Sec 5.5 (on page 19).
•	Same problem with the query in Sec 6.1 (on page 21).
•	Same problem with the example in Sec 6.2 (on page 21). The problem exists 
inside the <OPTIONALgp> as well.
•	Same problem with the example in Sec 6.3 (on page 22).
•	Same problem with the example in Sec 6.4 (on page 22).
•	Same problem with the example in Sec  8.2.3 (on page 28).
•	The example in Sec 8.3.3 (on page 30) uses ‘.’ as terminator for the last 
triple in the first <GRAPHgp>.
•	The example in Sec 8.3.4 (on page 31) uses ‘.’ as separator between <Bgp> 
and <GRAPHgp>.
•	The example in Sec 10.1 (on page 35) uses ‘.’ as separator between <Bgp> and 
<OPTIONALgp>.
•	The example in Sec 10.2.3 (on page 38) uses ‘.’ as terminator for the last 
triple in the <Bgp>.
•	The example in Sec 11 (on page 41, before Sec 11.1) uses ‘.’ as a separator 
between <Bgp> and <constraint>.
•	Same problem with the examples in Sec 11.4 and Sec 11.6.
Received on Tuesday, 20 February 2007 15:32:55 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:36 GMT