RE: RE : RE : RE : RE : Suggestion for SKOS FAQ

Dear all,
 
I understood the point explained by Stella and I agree.
 
But i would like to return to the proposal to make skos:broaderTransitive a
super-property of skos:broader.
 
I understood the point of Alistar that it is possible to have non-transitive
sub-properties of transitive properties and viceversa. I agree on that.     I
also clarify on my mind inheritance.
 
But:  what if i would like to express:
A skos:broader B
B skos:broader C
and assert that A not-skos:broader C?
 
in other words i would like to express intransitivity. How do i do that?
 
Also: is this topic associated to some issue? maybe issue 44 or there is a
more specific one?
 
Thanks
Margherita

 -----Original Message----- 
 From: public-esw-thes-request@w3.org on behalf of Antoine Isaac 
 Sent: Fri 3/14/2008 11:26 
 To: al@jku.at; SKOS 
 Cc: 
 Subject: RE : RE : RE : RE : Suggestion for SKOS FAQ
 
 


 Dear Andy,
 
 >> Is there a current draft for the new SKOS core as rdf? I can only
find 
 this one which doesn't include the new transitivity solution:
http://www.w3.org/2004/02/skos/core.rdf

 >>
 
 That's indeed an outdated one. There should be a new one by the time
SKOS goes candidate recommendation, but for the moment there is nothing
available
 
 >>
 I assume skos:transitiveBroader is an owl:TransitiveProperty
(http://www.w3.org/TR/owl-ref/#TransitiveProperty-def

 ). If skos:broader is a sub property of skos:broaderTransitive this 
 does not imply skos:broader is also an owl:TransitiveProperty! - it
is 
 no sub class it's just a sub property ;-)
 So, if I use the skos:whateverTransitive property e.g. in a SPARQL 
 query, I get the whole transitive closure of the concept relation and
if I use skos:broader/etc. I only get direct assertions, right? With 
 this approach it's possible to interpret relations as transitive by a
query/application although the author of the KOS did not even use 
 transitive properties, right? That's fine ;-)
 >>
 
 That's *exactly* this!
 
 Cheers,
 
 Antoine
 
 Thanks,
 Andy
 
 On Mar 13, 2008, at 1:51 PM, Antoine Isaac wrote:
 
 > I'm sorry I don't have time to read all your mail and answer point 
 > by point.
 >
 > But it seems really related to confusion about transitivity and 
 > inheritance.
 > You indeed assume that if something is transitive, then it has more
> information defined, and thus should be a sub-property of a non-
 > transitive property.
 >
 > But it is prefectly possible to say that a superproperty is 
 > transitive. That says something about its graph (that is, the 
 > couples (x,y) that are related by the property, as the As and Bs in
> your example).
 > But now, if you have a sub-property, formally it is defined as a
sub-
 > part of the graph. So you lose elements (couples), and something 
 > that was true at the level of the super-property (e.g.
transitivity) 
 > might not be true anymore for the sub-property.
 >
 > Example:
 > - one property 'blob1' defined by the graph {(a,b), (b,c), (a,c)} 
 > (it relates only these elements) is transitive
 > - one property 'blob2' defined by the graph {(a,b), (b,c)}
 > blob2 is a sub-property of blob1 and yet blob2 is not transitive.
 >
 > That's what happens currently in SKOS, where blob1 is 
 > broaderTransitive and blob2 is broader
 >
 > Antoine
 >
 >
 > -------- Message d'origine--------
 > De: Sini, Margherita (KCEW) [mailto:Margherita.Sini@fao.org]
 > Date: jeu. 13/03/2008 09:05
 > À: Antoine Isaac; Stephen Bounds; SKOS
 > Cc: al@jku.at
 > Objet : RE: RE : RE : Suggestion for SKOS FAQ
 >
 > Dear all,
 >
 > I appreciate the efforts from Alistar, Stephen and Simon to explain
> this, but
 > (sorry) unfortunately I am not convinced.. maybe I miss
something....
 > Let me summarize from my point of view so that you can tell me if I
> am wrong:
 >
 > - we say that for skos:broader we could not say if it is transitive
or
 > intransitive (it may be or not be = could be locally transitive but
> could be
 > also not transitive).
 > - we say that if somebody want to say that they broader 
 > relationships is
 > really transitive, can use a specific one "broaderTransitive"
 > - I think that in OWL, when we say subclassof we actually means "is
A"
 >
 > So this situation:
 >
 > skos:semanticRelation
 >   skos:broaderTransitive
 >     skos:broader
 >
 >   A skos:broader B
 >   B skos:broader C
 >
 > means also:
 >
 > 1)   skos:broader "isA" skos:broaderTransitive which I think is not
> what we
 > want...
 >
 > 2) We get the transitivity for free:
 >
 >   A skos:broaderTransitive B
 >   B skos:broaderTransitive C
 > therefore
 >   A skos:broaderTransitive C
 >
 > ... But what about if I wanted to say that
 >
 >   A skos:broader B
 >   B skos:broader C
 >
 > and they are not transitive?
 >
 > I think that if somebody wanted the trasitivity NEEDED to 
 > *explicitly assert*
 > statements ... otherwise we assume that all skos:broader are also
 > skos:broaderTransitive, no?
 >
 > Then we have:
 >
 > - super-properties make *less* restrictive statements about the
world.
 > skos:broader I think is less restrictive than
skos:broaderTransitive 
 > because
 > as I understood "skos:broader" we not not know about Transitivity,
but
 > "skos:broaderTransitive" IS transitive, so IT is more restrictive,
no?
 >
 > Then we have:
 >
 > >>>We can't reverse the order of skos:broaderTransitive and 
 > skos:broader in
 > the because of the transitive case.  If:
 > <<<
 >
 > skos:semanticRelation
 >   skos:broader
 >     skos:broaderTransitive
 >
 >    A skos:broaderTransitive B  and
 >    B skos:broaderTransitive C  then
 >    A skos:broaderTransitive C  but
 >
 >    A skos:broader C   YES because in this case we agreed that A and
> B and B
 > and C are related by  transitite broader
 >
 >
 > Therefore I can propose another solution:
 >
 >   skos:semanticRelation
 >     skos:broader
 >       skos:broaderTransitive
 >       skos:broaderIntransitive
 >
 >    A skos:broaderTransitive B  and
 >    B skos:broaderTransitive C  then
 >    A skos:broaderTransitive C  but
 >    therefore A skos:broader C   --> is correct to arrive here
 >
 >    A1 skos:broaderIntransitive B1  and
 >    B1 skos:broaderIntransitive C1  then
 >    A1 and C1  are not related
 >    therefore we cannot say A1 skos:broader C1   which is correct to
> arrive to
 > this conclusion because we agreed that A1 is broader than B1 and b1
> broader
 > than C1 but in an intransitivity way...
 >
 > Where I am wrong?
 > Thanks
 > Margherita
 >
 >
 > -----Original Message-----
 > From: Antoine Isaac [mailto:Antoine.Isaac@KB.nl]
 > Sent: 12 March 2008 13:09
 > To: Stephen Bounds; SKOS
 > Cc: Sini, Margherita (KCEW); al@jku.at
 > Subject: RE : RE : Suggestion for SKOS FAQ
 >
 >
 > Thanks a lot Stephen for your clarification.
 >
 > I would actually add: at some point we considered in the WG (and I
was
 > supporting this) that broaderTransitive could be actually a 
 > subproperty of
 > skos:broader.
 >
 > This actually would have matched cases for which you allow 
 > skos:broader to be
 > locally transitive (that is, on certain KOSs and not on others), 
 > which is
 > what we wanted (and still allow, on the condition that KOS creators
 > explicitly assert the 'extra' A skos:broader C -kind of links).
 >
 > But this was judged less convenient. Because then if you want to
say 
 > that the
 > broaders of a given KOS are transitive, you have to *explicitly 
 > assert*
 > statements of broaderTransitive.
 >
 > While with the current version, you get the transitivity for free: 
 > whenever
 > you assert a broader, there is a transitive one that is inferred
for 
 > it, de
 > facto building a transitive hierarchy for your KOS. Meanwhile, you 
 > can still
 > access your original skos:broader statements, without having them 
 > messed up
 > by the transitivity.
 >
 > Antoine
 >
 >
 > -------- Message d'origine--------
 > De: public-esw-thes-request@w3.org de la part de Stephen Bounds
 > Date: mar. 11/03/2008 22:39
 > À: SKOS
 > Cc: Sini, Margherita (KCEW); al@jku.at
 > Objet : Re: RE : Suggestion for SKOS FAQ
 >
 >
 > Hi Margaret & Andy,
 >
 > I thought that too when I first looked at the SKOS Primer, but you 
 > need
 > to remember that OWL sub-properties are subtractive, not additive.
 >
 > Another way of putting this is that super-properties make *less*
 > restrictive statements about the world.
 >
 > The full hierarchy of skos:broader is:
 >
 >   skos:semanticRelation
 >    skos:broaderTransitive
 >     skos:broader
 >
 > Which means that for A skos:broader B, this entails that:
 >
 >   A skos:broaderTransitive B  and
 >   A skos:semanticRelation B
 >
 > We can't reverse the order of skos:broaderTransitive and 
 > skos:broader in
 > the because of the transitive case.  If:
 >
 >    A skos:broaderTransitive B  and
 >    B skos:broaderTransitive C  then
 >    A skos:broaderTransitive C  but
 >
 >    A skos:broader C   is NOT entailed
 >
 > If skos:broader were a super-property of skos:broaderTransitive,
this
 > statement would also need to be true.
 >
 > Regards,
 >
 > -- Stephen.
 >
 > Sini, Margherita (KCEW) wrote:
 > > I agree with Andy, I also think it should be a sub-property, not
a
 > > super-property...
 > >
 > > Regards
 > > Margherita
 > >
 > >     -----Original Message-----
 > >     *From:* public-esw-thes-request@w3.org
 > >     [mailto:public-esw-thes-request@w3.org] *On Behalf Of
*Andreas
 > Langegger
 > >     *Sent:* 11 March 2008 12:14
 > >     *To:* Alasdair J G Gray
 > >     *Cc:* Antoine Isaac; Simon Spero; iperez@babel.ls.fi.upm.es; 
 > SKOS
 > >     *Subject:* Re: RE : Suggestion for SKOS FAQ
 > >
 > >     Hi,
 > >
 > >     first I din't pay much attention to your discussion, because
I
 > >     thought this case is clear... looking at the spec I read
 > >     "skos:broaderTransitive owl:subClassOf skos:broader" - but 
 > there it
 > >     says (to my surprise): skos:broaderTransitive and others are 
 > "super
 > >     properties" - why that?
 > >
 > >     If I would model this I would say:
 > >
 > >     skos:semanticRelation a owl:ObjectProperty .
 > >     skos:broader a skos:semanticRelation .
 > >     skos:narrower a skos:semanticRelation .
 > >     skos:broaderTransitive a skos:broader; a 
 > owl:TransitiveProperty .
 > >     skos:narrowerTrasnsitive a skos:narrower; a 
 > owl:TransitiveProperty .
 > >     and so on...
 > >
 > >     can anybody comment on this why the specs says "super 
 > property" and
 > >     not "sub property" ?
 > >     Whith the statements above I can deceide whether to allow
 > >     transitivity or not. And because of OWA, skos:broader not 
 > explicitly
 > >     asserted as a transtive property, it does not mean, that it 
 > _cannot
 > >     be_ transitive, sure it can, but it does not need to be
valid.
 > >
 > >     If a taxonomy should be ISO2788 compliant, just use the 
 > *Transitive
 > >     versions - so it's up to the modeler and not to the
application
 > >     which I think is fine.
 > >
 > >     regards
 > >     Andy
 >
 >
 
 
 
----------------------------------------------------------------------
 Dipl.-Ing.(FH) Andreas Langegger
 Institute for Applied Knowledge Processing
 Johannes Kepler University Linz
 A-4040 Linz, Altenberger Straße 69
 http://www.langegger.at <http://www.langegger.at/>

Received on Tuesday, 18 March 2008 16:56:25 UTC