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Re: Discussion of property paths, SPARQL and N3

From: Steve Harris <steve.harris@garlik.com>
Date: Fri, 29 Jan 2010 11:47:04 +0000
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <A8A31A0B-AEE2-4D8F-BD72-3C258B3B1E5D@garlik.com>
To: Andy Seaborne <andy.seaborne@talis.com>
On 29 Jan 2010, at 10:57, Andy Seaborne wrote:
> On 27/01/2010 12:58 PM, Andy Seaborne wrote:
>> http://lists.w3.org/Archives/Public/public-cwm-talk/2010JanMar/0002.html
>> and replies.
>>
>> Andy
>
> Now also a comment:
> http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2010Jan/0007.html
>
> One point arising is the use of "/" as the path follow symbol.  N3  
> uses "!" (after UUCP) and the design note
>
> http://www.w3.org/DesignIssues/N3Alternatives#Syntax
>
> where it is noted that N3 might acquire expression syntax so  
> reserving + - * / makes sense.
>
> * and + are already used in property paths.

I think the familiarity from regular expressions is a huge win.

> To add expressions in patterns to SPARQL, it would take some kind of  
> expression marker like `` or ?(?x+?y) (c.f. shell syntax).

Alternatively a path marker would be possible, but expression marker  
seems slightly more "natural" to me. Thinking out loud...

// for path expressions would evoke perl inline regex, but with the /  
for path separator as well it might be confusing:

/foaf:knows+/foaf:name/

with //, the path separator could be whitespace:

/foaf:knows+ foaf:name/

Anyway, I think it's fine as it is.

> To me "!" suggests "not".  "/" builds on file paths and paths in  
> HTTP URIs.

Agreed. It's 15+ years since I used a UUCP bang path.

- Steve

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Received on Friday, 29 January 2010 11:47:33 GMT

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