RE: shapes and classes: different

* Irene Polikoff <irene@topquadrant.com> [2015-01-26 18:22-0500]
> This is not really a question to me, but to the group that designed and
> maintains this vocabulary. It is a pretty "unwieldy" one although may be it
> has gotten cleaner lately? The use case it's designed for was, I believe,
> for people to publish information about themselves.  I don't know what
> constraints are needed for that.
> 
> Other vocabularies that have been designed for a broad use, often have
> constraints. SKOS has a number of constraints defined in its documentation.
> Folks that do FIBO seem to be pretty clear on their definitions and
> constraints. I believe this is true for any other group that develop
> vocabularies. They are the ones to decide on the constraints.
> 
> If I was to simply brainstorm, there could be a constraint that says that
> the range of foaf:knows must be a foaf:Person. Or a constraint that says you
> can't use both foaf:family_name and foaf:surname. It is either one or the
> other. Or a constraint that there can be only one foaf:birthday and it must
> be a date.
> 
> What is the significance of this question?

The LDOM proposal attaches constraints to classes, e.g.
[[
ex:Rectangle a rdfs:Class ; rdfs:subClassOf rdfs:Resource ;
  rdfs:label "Rectangle" ;
  ldom:property [
    ldom:predicate ex:height … ] …
]]

In <http://www.w3.org/mid/54C6D423.3070201@topquadrant.com>, Holger
said that one wouldn't attach them to e.g. foaf:Person. His stated
reason was that foaf:Person was designed for open world use, but I
believe it's more about whether it's a repurposable class. It seems
one should never attach constraints to the class if you may want to
use that class differently in a different context.


> Irene
> 
> -----Original Message-----
> From: Eric Prud'hommeaux [mailto:eric@w3.org] 
> Sent: Monday, January 26, 2015 4:50 PM
> To: Irene Polikoff
> Cc: Jerven Tjalling Bolleman; Peter F. Patel-Schneider; RDF Data Shapes
> Working Group
> Subject: Re: shapes and classes: different
> 
> * Irene Polikoff <irene@topquadrant.com> [2015-01-26 12:24-0500]
> > > Your word shape is my word owl:Class.
> > 
> > +1
> > 
> > So, the simplest solution is not to have a new thing called Shape.
> > 
> > Another option may be to use it as a type so that some classes can be of
> type Shape as well as Class.
> > 
> > This seems to be unnecessary though as every class is already a shape. At
> minimum, even if there are no other constraints declared for a class, it
> says that all instances belonging to it must have a certain type triple. If
> there is a class :Person, then its instances must have :Person1 a ::Person
> triple (whether it is asserted or inferred, doesn't matter). A very
> minimalistic data shape, but still a shape.
> 
> What constraints would you put on a reusable class like foaf:Person?
> 
> 
> > Irene
> > 
> > > On Jan 26, 2015, at 11:12 AM, Jerven Tjalling Bolleman
> <jerven.bolleman@isb-sib.ch> wrote:
> > > 
> > > I really can't help myself...
> > > 
> > >> On 26/01/15 15:12, Peter F. Patel-Schneider wrote:
> > >> -----BEGIN PGP SIGNED MESSAGE-----
> > >> Hash: SHA1
> > >> 
> > >> The most important aspect of classes is that you state that objects 
> > >> belong to them.  If you don't state that objects belong to X, X is not
> a class.
> > >> 
> > >> The most important aspect of shapes is that you provide conditions
> stating
> > >> precisely when an object belongs to them.   If you don't provide
> conditions
> > >> stating precisely when an object belongs to X, X is not a shape.
> > >> 
> > >> Having shapes also be classes implies that you state that objects 
> > >> belong to shapes.  Having classes also be shapes implies that you 
> > >> provide recognition conditions for classes. Both situations are 
> > >> possible, but both have consequences.
> > > Your word shape is my word owl:Class. Allowing class membership
> inference from recognition conditions is as normal as class member ship
> assertion directly in the data. But I am absolutely flabbergasted that I am
> having this argument with one of the OWL2 editors!
> > > 
> > > Basically I am reading your response as class membership only inferred
> is "shape membership". Class membership asserted is not "shape membership".
> Or paraphrased: Shapes only allows triples with the shape:member predicate
> (IMO equivalent to rdf:type) to be inferred and not asserted.
> > > 
> > > 
> > >> 
> > >> peter
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> > >> 
> > > 
> > > --
> > > -------------------------------------------------------------------
> > > Jerven Bolleman                        Jerven.Bolleman@isb-sib.ch
> > > SIB Swiss Institute of Bioinformatics  Tel: +41 (0)22 379 58 85
> > > CMU, rue Michel Servet 1               Fax: +41 (0)22 379 58 58
> > > 1211 Geneve 4,
> > > Switzerland     www.isb-sib.ch - www.uniprot.org
> > > Follow us at https://twitter.com/#!/uniprot
> > > -------------------------------------------------------------------
> > > 
> 
> -- 
> -ericP
> 
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-- 
-ericP

office: +1.617.599.3509
mobile: +33.6.80.80.35.59

(eric@w3.org)
Feel free to forward this message to any list for any purpose other than
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There are subtle nuances encoded in font variation and clever layout
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Received on Tuesday, 27 January 2015 20:54:33 UTC