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Re: Shapes/ShEx or the worrying issue of yet another syntax and lack of validated vision.

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Sun, 20 Jul 2014 07:54:19 -0700
Message-ID: <53CBD81B.2070200@gmail.com>
To: Simon Spero <sesuncedu@gmail.com>
CC: Kendall Clark <kendall@clarkparsia.com>, Sandro Hawke <sandro@w3.org>, Eric Prud'hommeaux <eric@w3.org>, "Dam, Jesse van" <jesse.vandam@wur.nl>, Jerven Bolleman <jerven.bolleman@isb-sib.ch>, "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>, Evren Sirin <evren@clarkparsia.com>, Jose Emilio Labra Gayo <jelabra@gmail.com>, Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>
This does seem rather complex.  I don't see why you need to know all this 
stuff just to say, for example, that people have names and students have 
universities.

peter


On 07/20/2014 06:05 AM, Simon Spero wrote:
> On Jul 20, 2014 5:05 AM, "Peter F. Patel-Schneider" <pfpschneider@gmail.com
> <mailto:pfpschneider@gmail.com>> wrote:
>  >
>  > It is very hard to see how ShEx constraints can be associated with
> instances of RDFS types.  I view the ability to associate constraints with
> instances of types as the most important aspect of a constraint system, hence
> my questions about how this can be done in ShEx.
>
> There's an obvious approach, but I don't think it is right?
>
> If only a single pattern may match a predicate then there can only be a single
> pattern matching rdf:type.
>
> If the entire class hierarchy is known at the time that the pattern is
> created, then a pattern  can be created as a set of disjuncts.
> For each acceptable subclass there would be a disjunct  for  each member S of
> the power set of superclasses of that subclass, with a value set for rdf:type
> consisting of the   subclass plus all members of S, with a fixed cardinality
> on the pattern equal to the size of the value set.
>
> As long as the matching is against a graph, so that duplicate triples are not
> present, this should match all and only the desired types.
>
> Fewer patterns could be used if all super classes are required to be present
> (one pattern for each distinct set of superclasses of an acceptable class that
> does not contain that any acceptable class). The value set for each pattern
> would contain the superclasses, plus each acceptable class for which those
> classes are the  non-acceptable superclasses. The minimum cardinality would be
> one more than that of the set of superclasses.
>
> If inferencing is not allowed, and no superclasses that are not sufficient for
> a match are allowed, then a value set of just the sufficient classes, with
> minimum cardinality 1 would suffice.
>
> This seems too complicated to be the right way,  so I may have missed something.
>
Received on Sunday, 20 July 2014 14:54:48 UTC

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