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Re: summary on options for JP-4 Comment about the semantics of property paths

From: Gregory Williams <greg@evilfunhouse.com>
Date: Sat, 11 Feb 2012 13:21:33 -0500
Cc: "Lee Feigenbaum" <lee@thefigtrees.net>, "SPARQL Working Group" <public-rdf-dawg@w3.org>
Message-Id: <F3C48115-2AEB-4B1A-9F4B-549F722D5464@evilfunhouse.com>
To: Axel Polleres <axel.polleres@deri.org>
On Feb 11, 2012, at 1:14 PM, Axel Polleres wrote:

> To make this more tangible, what I was thinking is the following: 
> 
> Take 
> 
> Q:  SELECT ?S WHERE { ?s :p/:q [] }
> 
> and the following graph
> 
>  :s1 :p [ :q :o1 ].
>  :s1 :p [ :q :o1 ].
>  :s1 :p [ :q :o2 ].

I think this is a particularly strange query to use to base this discussion, because:

a) (as Andy noted) things get particularly strange when you don't have a term on one end of the path
b) it's a fixed length path, which isn't the underlying problem as I understand it. I certainly hope we're not discussing changing the cardinality semantics of fixed-length paths…

I'm having a hard time coming up with a real query like this that used arbitrary-length paths, that didn't involve counting, and that couldn't be done with an ASK query.

.greg
Received on Saturday, 11 February 2012 18:21:58 GMT

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