Re: shapes-ISSUE-22 (recursion): Treatment of recursive shape definitions [SHACL Spec]

Richard,

Recursive shapes are very useful.

I think there are two subcases:
1. Shapes that use the high-level language
2. Shapes that use arbitrary SPARQL templates

For case 1, I am confident that we can precisely specify the
semantics, without being particularly clever.
For case 2, in general this is probably undecidable, however we might
be able to say something about suitably restricted templates

-- Arthur

On Sat, Mar 28, 2015 at 4:12 PM, RDF Data Shapes Working Group Issue
Tracker <sysbot+tracker@w3.org> wrote:
> shapes-ISSUE-22 (recursion): Treatment of recursive shape definitions [SHACL Spec]
>
> http://www.w3.org/2014/data-shapes/track/issues/22
>
> Raised by: Richard Cyganiak
> On product: SHACL Spec
>
> A shape definition may refer to itself, either directly or indirectly. For example, in a bug tracker, issues may depend on other issues. Such shapes are problematic if there are cycles in the data. Before one can determine if a node belongs to the shape, one may first have to know whether it belongs to the shape.
>
> Proposals for treating this include:
>
> - Doing something very clever in the Semantics
> - Syntactic conditions that outlaws recursive shape defintions
> - Allowing recursive shape definitions, but doing something to treat them as informative documentation only
>
>
>

Received on Thursday, 2 April 2015 18:10:28 UTC