$)CRe: input document for discussion on Friday From: $)CGuido Vetere <gvetere@it.ibm.com>
Date: Wed, 31 Oct 2012 16:41:05 +0100
To: $)CPhilipp Cimiano <cimiano@cit-ec.uni-bielefeld.de> Cc: $)C"public-ontolex@w3.org" <public-ontolex@w3.org>
Message-ID: <OFD1836761.1F63D50B-ONC1257AA8.00549F6C-C1257AA8.00562C48@it.ibm.com>
$)CPhilipp, \forall x,y hasSense(x,y) \wedge hasSense(x,z) \wedge representedBy(y,c) \wedge representedBy(z,c) \rightarrow x=y If you mean \forall y,z ... y=z (i.e. whether being 'representedBy' the same concept means for two senses being the very same sense) then my answer would be definitely no, however this depends on the intended meaning of 'representedBy' which is obscure to me. Guido Vetere Manager, Center for Advanced Studies IBM Italia _________________________________________________ Rome Trento Via Sciangai 53 Via Sommarive 18 00144 Roma, Italy 38123 Povo in Trento, Italy +39 (0)6 59662137 +39 (0)461 312312 Mobile: +39 3357454658 _________________________________________________ Philipp Cimiano <cimiano@cit-ec.uni-bielefeld.de> 31/10/2012 16:02 To John McCrae <jmccrae@cit-ec.uni-bielefeld.de> cc "public-ontolex@w3.org" <public-ontolex@w3.org> Subject Re: input document for discussion on Friday Hi John, all, see below. Am 31.10.12 14:34, schrieb John McCrae: On Wed, Oct 31, 2012 at 1:16 PM, Philipp Cimiano < cimiano@cit-ec.uni-bielefeld.de> wrote: John, all, comments back... Am 31.10.12 12:59, schrieb John McCrae: Hi, Some comments ex:lemon rdf:type ontolex:Lex. ex:lemon ontolex:hasSense lemon_1. lemon_1 owl:subClassOf <http://dbpedia.org/page/Lemon>. ex:lemon ontolex:hasSense lemon_2. Thus :lemon_2 is an individual lemon_2 owl:subClassOf ex:DefectiveItem. Thus :lemon_2 is a class This leads to a punning of the sense... is this intended? Yes, intended to capture the dual role of a sense. And further (not expressible in OWL2 DL): "#x; y lex(x; y) "$s Sense(s) ^ hasSense(x; s) ^ representedBy(s; y)

I really don't think we should go beyond OWL2 DL

We will not. This is simply not expressable in OWL2 DL. This is an axiom
that might need to be ensured in implementations or not at all. To be
discussed.

it is true that it blows up the complexity of the
model. However, it simplifies the usage of the model

No, it's not. The model is in principle more complex, but people use
always that subset that fits their need. They have their own simple view
on a complex model.

I think this can be handled eff ectively by query expansion (as above) in
any
implementation of an API for the lexicon-ontology model
Not all implementations will be query based... for example OWLAPI isn't

Sure, there will be different ways of implementing this. Query expansion
is not the only one. Relying on OWL reasoning is another one.
SPARQL construct is another one. And a procedural API-specific
implementation is another one. We could provide some recommendations on
this. I am not suggesting that we ignore implementaiton, but that we do
not put it at the centre of our discussions.

This can be done through SPARQL-construct
The construct query is:

CONSTRUCT { ?entry ontolex:hasSense _:sense .
_:sense ontolex:representedBy ?entity }
WHERE {
?entry ontolex:ref ?entity
}

Of course, this leads to issues as the constructed sense is a blank
node... I believe that like OWL we should advise against the use of blank
nodes for "concepts" within the lexicon. See
http://richard.cyganiak.de/blog/2011/03/blank-nodes-considered-harmful/
http://milicicvuk.com/blog/2011/07/14/problems-of-the-rdf-model-blank-nodes/
etc.

ex:lemon rdf:type ontolex:Lex.
ex:lemon ontolex:hasSense lemon_1.
lemon_1 ontolex:representedBy <http://dbpedia.org/page/Lemon>.
ex:lemon ontolex:ref <http://dbpedia.org/page/Lemon>.

Then the question certainly is how many senses I get back with the query.
Ideally, I would like to get one sense back.
Yeah technically that is what should happen... however here we have to
apply the semantics of RDFS, in that the blank node we construct is
matched to lemon_1. Of course, the downside to this is that this is
non-polynomial to solve with generic solvers... and tricky in a
specialized implementation (also I think it is incompatible with OWL2-DL)
One question: do we want to model that for any pair of class and lex,
there
is at most one sense relating them? Can we do this in OWL?
I would say no, I think we have found use cases for multiple sense between
the same entry/entity in lemon (but can't remember at the moment... it'll
come to me)

As for in OWL... is this not it?

??1.lex.Lex

No, this says that there is exactly one lexicalization per concept ;-)
Yeah that was dumb.... actually, it may not be possible

A good start is
represents ? represents?)v !U sameRep
sense?)v ? sense !U sameLex

Then the very simple axiom does the trick

"# x,y : sameRep(x,y) !|sameLex(x,y) !f x = y

Right. That goes in the right direction. However, the last rule is not
expressible in OWL 2 DL unfortunately. Essentially, one has two paths
between variables x,y in the premise, so no way to represent this as a
property chain.

I think it is not a huge problem, but ... the thing is that if we infer
senses (that are existentially quantified), then
we need to equate them with senses that are explicitly stated as
connecting the same pair of lexical entry and concept. Well, do we
actually? Or can we live with the fact that in practice there are many
identical senses the identity of which is not stated?

Btw: this is not per se a problem of blank nodes. We would have the same
problem if we would skolemize, i.e. introduce a fresh URI.

I think we should avoid the problem of introducing existentially
quantified senses, no matter if we introduce them via blank nodes or via a
skolem constant.

So, the shortcut should be handled IMHO at retrieval time only.

Independently of whether the above axioms are representable in OWL, I
would like to know whether we agree on the fact that:

\forall x,y hasSense(x,y) \wedge hasSense(x,z) \wedge representedBy(y,c)
\wedge representedBy(z,c) \rightarrow x=y

Is that our understanding of how a sense behaves?

Philipp.
However this is (probably) impossible to represent in OWL:

I don't know if there is another way

Regards,
John

Regards,
John

On Wed, Oct 31, 2012 at 9:45 AM, Philipp Cimiano <
cimiano@cit-ec.uni-bielefeld.de> wrote:
Dear all,

I have compiled a brief document as input for our discussion on Friday.
We will discuss this proposal on Friday and collect comments and
objections.

Best regards,

Philipp.

--
Prof. Dr. Philipp Cimiano
Semantic Computing Group
Excellence Cluster - Cognitive Interaction Technology (CITEC)
University of Bielefeld

Phone: +49 521 106 12249
Fax: +49 521 106 12412
Mail: cimiano@cit-ec.uni-bielefeld.de

Room H-127
Morgenbreede 39
33615 Bielefeld

--
Prof. Dr. Philipp Cimiano
Semantic Computing Group
Excellence Cluster - Cognitive Interaction Technology (CITEC)
University of Bielefeld

Phone: +49 521 106 12249
Fax: +49 521 106 12412
Mail: cimiano@cit-ec.uni-bielefeld.de

Room H-127
Morgenbreede 39
33615 Bielefeld

--
Prof. Dr. Philipp Cimiano
Semantic Computing Group
Excellence Cluster - Cognitive Interaction Technology (CITEC)
University of Bielefeld

Phone: +49 521 106 12249
Fax: +49 521 106 12412
Mail: cimiano@cit-ec.uni-bielefeld.de

Room H-127
Morgenbreede 39
33615 Bielefeld

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