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RE: WordNet modelling in Lemon and SKOS

From: Armando Stellato <stellato@info.uniroma2.it>
Date: Wed, 24 Apr 2013 15:34:41 +0200
To: "'John McCrae'" <jmccrae@cit-ec.uni-bielefeld.de>
Cc: "'Aldo Gangemi'" <aldo.gangemi@cnr.it>, "'Philipp Cimiano'" <cimiano@cit-ec.uni-bielefeld.de>, "'public-ontolex'" <public-ontolex@w3.org>
Message-ID: <04db01ce40f0$7ab4efd0$701ecf70$@info.uniroma2.it>
Hi John,


very quick replies to some points in your email:


I agree that WordNet's synset could be a subclass of a Lexical Concept class, however might it not make more sense (especially with respect to dissemination) to just call it Synset?


I just think this would accommodate for something more general, I’m thinking also of other lexical resources and maybe Synset would not always fit perfectly, still having this sufficiently general (as being a superclass of wn:Synset) and sufficiently specific (as different from LexicalSense/Sense) class, made explicit in the ontolex vocabulary, could support in a plethora of scenarios.


Note: LexicalSense cannot be a subclass of semio:Meaning, it should be a subtype of the tuple (semio:Expression,semio:Meaning)


Initially I said the same as you (mostly in my discussions about the Sense/LexicalConcept thing). On the other side, Aldo convinced me that, in the interpretation which we give of these objects in terms of the semiotics ontology, they both convey a form of meaning. I agree, providing we embrace this interpretation of the Expression/Meaning/Reference. However, in my last email I said that, IMHO, beyond proper “tagging” to a theory of significance, this mapping to semiotics.owl does help much. To the purpose of a proper perspective on semiotics (very big IMHO here, especially the “H” :-D ), all the entities we may ever write are just symbols to me, and then Meaning is in our head and Reference is in the world.

Given this, I admit my limits on the matter, and will take a step back on discussing any mapping to semiotics.owl.


I would however be strongly in favour of having the following path still in the model:


LexicalEntry --sense--> LexicalSense --reference--> (OntologyEntity)*


Providing we agree on LexicalSense (and it seems we do), yes :-)   Each path can be shortened by property chains and, obviously, whenever you don’t have any explicit representation of a LexicalSense or LexicalConcept, you should be free to maintain the path above.

I would still argue a bit OntologyEntity, but ok.


The primary reason for this is simply to allow for backwards compatibility with the current lemon model.


To me it would be 100% important to reach a totally agreed consensus on naming (other than the model), but unless of strong opposition for certain names, surely backward compatibility should have an important weight. I personally only don’t like LexicalSense for the reasons described in the previous email (which make sense once we have the notion of LexicalSense and LexicalConcept), but if I’m alone, let’s go along with LexicalSense :-)


Furthermore, I think that the distinction Aldo makes between type A and type B modelling requirements is valid and important. In particular, it seems that type A modelling will involve not using an ontology entity (using a three-element path like below) and type B modelling will not use LexicalConcept (using a path as above). 


LexicalEntry --sense--> LexicalSense --lexConcept--> LexicalConcept


In line with what I said above, if we have to depict a full path (I’m using property names from your model), it would be:


LexicalEntry --sense--> LexicalSense --lexConcept--> LexicalConcept -- conceptualizes --> (OntologyEntity)*


Then, obviously, shortcuts (pchains), can be defined. For instance, not considering a form of conceptual Meaning is a possibility (if it is not made explicit by some lexical resource, then it can be absolutely removed), so from the above full path you can remove the LexicalConcept and have LexicalSense directly connected to (OntologyEntity)* through :reference, thus:


LexicalEntry --sense--> LexicalSense --reference--> (OntologyEntity)*   (so plain old Lemon)


This depends on the context however. If I have to explicitly use (taking benefit from it) WordNet synsets, on the contrary, I maybe more interested in the triad:


LexicalEntry --expresses--> LexicalConcept --conceptualizes--> (OntologyEntity)*        


as the LexicalSense may be not necessary. A wide literature on the use of WordNet in ontology mapping would suggest that. You will not read about the use of wordsenses, while synsets are widely used and linked, as an interlingua for achieving consensus on a mapping under a less-ambiguous grounding.  I think in fact that use cases would help us to: 

1)      Disambiguate any possible misalignment we may have in interpreting such elements

2)      Understand what is needed


The second clear issue that comes from this modelling is to do with the levels of annotation/linking. By which I mean that we need to be clear in the model which annotations & relationships belong should be part of the LexicalSense vs. LexicalConcept vs. OntologyEntity


Definitely yes. It is the kind of grounding which I’m telling will help a lot in understanding what we are using and if/where it is needed.

I think, we respect to the things below (the “guesses” in your email), making examples will help. We could even stop for a while and start working on examples.

Just one comment on a thing I’m pretty sure of:




* Anotnymy


Antonymy holds between LexicalSenses, and not between LexicalConcepts. See description of antonymy (end of page 7) on [1]:

“For example, the meanings {rise, ascend} and {fall, descend} may be conceptual opposites, but they are not antonyms; [rise/fall] are antonyms and so are [ascend/descend]”.

Notice that the expression used by Miller for wordforms and word meanings may be misleading.

Concretely, when he says “between word meanings”, he says that in wordnet, you have a pointer which goes from a synset to a synset (hypernymy).

when he says “between word forms”, he says that in wordnet, you have a pointer which goes exactly from a sense (intended as a <word,synset> pair) to a sense.


So far, we should distinguish between:

1)      purely lexical relationships (hold between LexicalEntries). These are not present in WordNet.

2)      Semantic Relations holding between LexicalEntries considered in a given Semantic Context, thus, in short, between LexicalSenses (antonymy above is an example). 

3)      Semantic Relations holding between LexicalConcepts (wordnet’s hypernymy falls here)


Note that these Semantic Relations from point 2) in WordNet are called LexicalRelations (though Miller refers to both of them as Semantic Relations holding between different objects)


Surely, while WordNet is not the only thing we care about in OntoLex, the grounding to WordNet helps in clarifying aspects of things which we are defining and where adopted terminology may confuse. At the same time, I think more concrete examples may help.





* The naming of the OntologyEntity class is technically irrelevant as it cannot be an owl:Class as object properties, data properties and individuals (as well as datatypes and sets) are valid so it is best that formally it's name is simply omitted. 

Totally agree, I put owl:Thing as the superclass in my model, and merely relied on the role defined in the same block as “target conceptual model” (maybe “target entity” would be even more appropriate).

[1]  <http://wordnetcode.princeton.edu/5papers.pdf> http://wordnetcode.princeton.edu/5papers.pdf



On Wed, Apr 24, 2013 at 3:38 AM, Armando Stellato < <mailto:stellato@info.uniroma2.it> stellato@info.uniroma2.it> wrote:

Hi Aldo,

Fine. Actually since the naming of concepts was still to be assessed, and since in some cases we could have been reusing specific classes from existing vocabularies, I used that informal labeling in the upper part of the boxes for clarifying their role, and an explicit reference to the proposed class in the lower one.
Thus "target conceptual model" was intended to capture actually elements of possibly different models (and in fact the least subsuming class is owl:Thing) so I confirm your hypothesis.
I must admit I only grasp partially the reason for which we should consider differently type-A and type-B models. My perspective, wrt, for instance, the triangle of Meaning, is that in-any-case what we formally write are still symbols (progressively richer in their description  ), which are then translated into references in our mind which refer to referents in the world.
And in this sense a synset, for instance, is still a symbol which, thanks to the set of synonyns in it, and the gloss etc.. better drives the access to a reference in our minds than a single word. In terms of Sinn and Bedeutung, an owl:Class has intensional properties as much as a skos:Concept has, plus it may restrict (through a set of formal constraints) its extension, the interpretations of which, however, are still infinite. In this sense, Words, skos:Concepts, owl:Classes are all "expressions", and referents are totally out of our representation game. Thus, any meaning/reference distinction is not really clear to me. Much the same way, how would u consider an owl:Individual wrt a skos:Concept (well actually a concept is an individual in owl terms..) Are not them both purely intensional objects?  
However, I may be easily wrong in that, and will not delve further in the discussion, so one practical question:
Suppose I've a domain concept scheme (e.g. Agrovoc) and a "conceptualized" lexical resources such as WordNet. Beyond any possible linking to meaning/reference etc.. would you see it as possible to have some form of "tagging" of the domain concept scheme with wordnet's synsets, where it is clear (in ontolex) that the synsets are not (only) mere skos:Concepts (thus to be mapped through ordinary mapping relation, eg from skos) and are instead lexical objects (instances of LexicalConcept in particular) which can be used to enrich the domain concepts?



Da: Aldo Gangemi <mailto:aldo.gangemi@cnr.it> 
Inviato: ‎24/‎04/‎2013 00.28
A: Armando Stellato <mailto:stellato@info.uniroma2.it> 
Cc: Aldo Gangemi <mailto:aldo.gangemi@cnr.it> ; 'John McCrae' <mailto:jmccrae@cit-ec.uni-bielefeld.de> ; 'Philipp Cimiano' <mailto:cimiano@cit-ec.uni-bielefeld.de> ; 'public-ontolex' <mailto:public-ontolex@w3.org> 

Oggetto: Re: WordNet modelling in Lemon and SKOS

Hi Armando, John, all,


On Apr 23, 2013, at 11:19:48 PM , "Armando Stellato" <stellato@info.uniroma2.it <mailto:stellato@info.uniroma2.it> > wrote:

Dear John,


After seeing your updated scheme, I think we are almost there. I had a short call with Aldo for checking the only one thing I was a bit uncertain of in his email (the double subclassing he proposed for WordNet’s WordSense/Synset under the ontolex:LexicalSense umbrella).

I’m resuming a few points here, and I ask Aldo to confirm if I’m properly reporting what we discussed (obviously I’m cutting most of the conversation and report only the main questions and where we ended up).


thanks for the summary :)


Armando: Why both wn:WordSense and wn:Synset subclasses of LexicalSense?

Aldo: they are both a form of Meaning. These can be totally disjoint classes as u said in your email, still being under the same superclass.

Armando: Ok, let’s go back to the linking to semiotics.owl… ok for both wn:WordSense and wn:Synset under semio:Meaning…they are both a form of meaning (thus both rdfs:subClassOf semio:Meaning) and I agree… but then, the engineer in me tells: <ok, this is a proper “tagging”, but how can these be used operatively?> I mean, ok for the general Meaning class in semiotics.owl, but LexicalSense cannot be an Umbrella for both too…our ontolex model should be general enough to cover different resources, and specific enough to cover in detail the most important aspects of them. To me, I would like WordNet to be opaquely handled by agents as an instance of a Lexical Resouce modeled in OntoLex. I’m thinking about some of the use cases, where smart agents covering given tasks (such as Ontology Mapping) may benefit of the implicit perspective on WordNet given through OntoLex glasses (a monolingual resource, with a conceptual structure etc…), and can adapt this sort of “ontolex fingerprint” of the resource into their general mapping strategies (this is also where the metadata part of the language will come into play). “Plugging” another resource should work as well, as much as its content can be seen through a proper mapping inside the OntoLex vocabulary.
So I suggest to make explicit in our model the existence of “Senses of LexicalEntries”, let’s call them LexicalSense or just Sense (e.g. specifically, a superclass of WordSenses in wordnet) and LexicalConcepts (specifically, a superclass of synsets in WordNet). Then I agreed that both Sense and LexicalConcept are tagged (subClassOf) as (different types of) Meanings, for the purpose of properly representing them under the Triad in semiotics.owl

Aldo agrees on having these two distinct elements in OntoLex too, and bound them under the common umbrella of semio:Meaning.


Confirmed. I have no issue about creating intermediate classes whatsoever, provided we all agree on the intuition about expressions, (intensional) meanings, and (extensional) references.


Concerning the diagram, I'm ok with links and names. 


My only observation is about "TargetConceptualModel" (not really discussed with Armando): if that is a class of conceptual models (as the name suggests), why should it be a subclass of Reference. I'd call it better OntologyEntity (as Lemon does, as well as LRI, the multilingual ontolex model made in NeOn project in 2008), and put a link between OntologyEntity and the ontology that defines it.

However, maybe you want to talk about arbitrary conceptual models and their elements. For this I think we need some more clarification, because there are two types of conceptual models:


A) purely intensional conceptual models, like SKOS models, classification schems, thesauri, synsets, lexical frames, etc.

B) formally interpreted conceptual models, like ontologies, ER schemas, UML class diagrams (under ER-like semantics), etc.


For type-A conceptual models, I am still recalcitrant to accept their elements as references, since no clear extensional intuition is granted, except under a sort of "stipulation" by which I accept the risks of interpreting them extensionally (old SKOS did that by having skos:Concept as both rdfs:subClassOf owl:Thing and of rdfs:Class). I think no default extensional choice like that should be made. 


For type-B conceptual models, we can safely adopt the extensional interpretation.


Now, since this community group works under the semantic web and linked data umbrella, I do not see the necessity of forcing our model to deal with debatable choices wrt type-A conceptual models, which can be instead interpreted in the context of the Meaning class (that's because I put skos:Concept as a subclass of semio:Meaning).


I won't be able (last time hopely) to attend Friday's telco, but will be active in the email discussion.




I’m attaching (and reporting here below) an updated version of the model I sent in my last email, with the mapping to Semiotics.owl which followed the discussion with Aldo. As you may see, it is pretty similar to the last one you sent (modulo naming choices and the double linking to semio:Meaning).

Regarding chosen names, just a couple of comments:


1)      I suggested, as a OntoLex superclass for Synset, the name Lexical Concept (ref. Miller’s paper, where he defines synsets as a form of “Lexical Concepts”). This captures the idea of a given set of LexicalEntries hinting at a (non explicit nor formally defined) concept. Note (not in the figure) that this LexicalConcept may be a subclass of skos:Concept. An alternative could be “LexicalizedConcept”, though the former one surely sounds better :-)

2)      Conversely, for the other class reifying the sense relationship, I’m not sure about the appropriateness of the name LexicalSense, as in this name “Lexical” seems an adjective of “Sense”. But, IMHO, it is not. LexicalSense is more specifically the sense of a given Lexical Entry. Thus the proper name should be LexicalEntrySense (in fact, in WordNet - limiting lexical entries to be words - we have the class WordSense). However LexicalEntrySense is rather long and ambiguous to be parsed. Other choice could be SenseOfLexicalEntry (rather ugly), or simply (my preference), Sense. Btw, just my small note on that and absolutely can be left as is…but I really cannot grasp the meaning of such an expression.  Simply, the step from the expression “LexicalSense” to its intended meaning of “Sense of a Lexical Entry” to me is not intuitive.

3)      I chose the ontolex:sense property to go from LexicalEntry to LexicalConcept. To me it is intuitive, as (grounding to WordNet, for instance), the sense of a Word lies in its linking to a Synset (or in general, to a unit of meaning). And then we can reify this relation into a Sense class as there can be many important things to say about it. However, I understand that following ontology modelling conventions, one could expect the ontolex:sense property to link to instances of a Sense class… so open to opinions (and proposals) for this property renaming. Even those from John’s last model could be reasonable.








From:  <mailto:johnmccrae@gmail.com> johnmccrae@gmail.com [mailto:johnmccrae@ <mailto:johnmccrae@>  <http://gmail.com> gmail.com] On Behalf Of John McCrae
Sent: venerdì 19 aprile 2013 10.44
To: Armando Stellato
Cc: Aldo Gangemi; Philipp Cimiano; public-ontolex
Subject: Re: WordNet modelling in Lemon and SKOS




While Aldo's model is very elegant it is not possible to have lexical sense as a subset of skos:Concept for a simple reason: the lexical sense is defined for only a single lexeme, while the skos:Concept can be used for multiple lexemes.


For this key reason we need to have a "lexical sense" object that is between the lexical entry and its meaning. If you are uncomfortable with this object then you can view it as a simple reification (although I would contend it is a very real object). In fact this is nothing more than the traditional lexicographic "word sense", see  <http://en.wikipedia.org/wiki/Word_sense> http://en.wikipedia.org/wiki/Word_sense.


I rename the "lexical sense" object of Aldo's model to "concept" or following WordNet a "synset"



[il messaggio originale non è incluso]

Received on Wednesday, 24 April 2013 13:35:28 UTC

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