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Re: [TF-PP] Possible starting points

From: Chimezie Ogbuji <ogbujic@ccf.org>
Date: Tue, 29 Sep 2009 09:31:48 -0400
To: "Seaborne, Andy" <andy.seaborne@hp.com>, "SPARQL Working Group" <public-rdf-dawg@w3.org>
Message-ID: <C6E78484.CBB6%ogbujic@ccf.org>
/me reminisces over Versa

On 9/29/09 7:12 AM, "Seaborne, Andy" <andy.seaborne@hp.com> wrote:
> I've tried to list the main possibilities in terms of styles and approach as
> starting points: all have variations and areas of uncertainty (e.g. ordering
> of results).
> 1/ Property paths only mention IRIs or prefixed names.

In Versa's forward traversal operators, the properties along the paths could
only be restricted via explicit URI ref (Qname, etc.).

subjects - predicates -> boolean

"[..]Statements that have matched the first criteria (the subjects
expression) are examined and excluded if their predicate is not a member of
this resulting list."

So predicate matching can only be done directly or WRT the URIs of the
resources that are subjects of the path

So I favor this.
> The most conservative choice. Still need to relate to entailment.

It should be easy to relate to entailment as no 'new' names are introduced.

> 2/ Property paths with variables and IRIs or prefixed names.
> (issues include restriction of what can be asked a la ?p* discussion)


> 3/ With access to the length of the path matched
> Issues include how multiple paths between two nodes are handled (two lengths
> possible).

Versa didn't have a way to filter by the length of a path traversed except
as a 'callout' to a transitive closure query that returned the path.  This
might have computational implications


-- Chime


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Received on Tuesday, 29 September 2009 13:33:22 UTC

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